Tm5_620_Facilities Engineering Maintenance and Repair of Architectural and Structural Elements of Buildings and Structures

ARMY TM 5-620NAVY NAVFAC MO-111AIR FORCE AFP 91-23

FACILITIES ENGINEERINGMAINTENANCE AND REPAIR OF

ARCHITECTURAL AND STRUCTURALELEMENTS

OF BUILDINGS AND STRUCTURES

DEPARTMENTS OF THE ARMY, THE NAVY, AND THE AIR FORCEMAY 1990

*TM 5-620/NAVFAC MO-111/AFP 91-23

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Army Manual HeadquartersTM 5-620 Departments of the Army, Navy Manual the Navy and the Air ForceNAVFAC MO-111 WASHINGTON, DC, May 10, 1990

Air Force PamphletAFP 91-23

FACILITIES ENGINEERINGMAINTENANCE AND REPAIR OF

ARCHITECTURAL AND STRUCTURAL ELEMENTSOF BUILDINGS AND STRUCTURES

Page

CHAPTER 1 INTRODUCTION . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1-1Section I General . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1-1Section II Definitions . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1-1Section III Work Excluded . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1-2Section IV Standards of Maintenance . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1-2Section V Maps, Plans and Building Numbering . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1-2Section VI Timely Repair . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1-3CHAPTER 2 FOUNDATIONS AND CRAWL SPACES . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 2-1Section I Foundations . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 2-1Section II Concrete Slabs on Grade . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 2-9Section III Moisture Control . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 2-20Section IV Crawl Spaces . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 2-32CHAPTER 3 FRAMING-STRUCTURAL COMPONENTS . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 3-1Section 1 Wood Framing . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 3-1Section II Wall and Partition Framing . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 3-12Section III Steel Framing . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 3-15Section IV Roof Framing . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 3-18Section V Glued-Laminated Wood Frames . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 3-73CHAPTER EXTERIOR WALLS . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 4-1Section I Classification of Walls . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 4-1Section II Wood Exteriors . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 4-1Section III Concrete and Masonry . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 4-9Section IV Metal Siding . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 4-23Section V Mineral and Chemical Products . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 4-26Section VI Exterior Insulating Systems . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 4-27CHAPTER 5 INTERIOR WALLS, PARTITIONS AND CEILINGS . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 5-1Section I Introduction . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 5-1Section II Repair and Maintenance of Plaster and Tile . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 5-3Section III Repair and Maintenance of Dry-Wall Construction . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 5-7Section IV Fire Protection . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 5-11Section V Acoustics . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 5-12CHAPTER 6 FLOORS AND STAIRS . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 6-1Section I General . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 6-1Section II Wood Floors . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 6-2Section III Concrete Floors . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 6-7

_________________*This manual supersedes TM 5-620, dated March 1958.

*TM 5-620/NAVFAC MO-111/AFP 91-23

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Section IV Terrazzo Floors . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 6-11Section V Magnesium-Oxychloride Floors . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 6-12Section VI Clay Tile Floors . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 6-15Section VII Mastic Floors . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 6-15Section VIII Conductive Floors . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 6-16Section IX Resilient Floor Coverings . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 6-16Section X Resinous Floor Finishes . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 6-23Section XI Stairs . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 6-25Section XII Carpet . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 6-26CHAPTER 7 DOORS, WINDOWS, AND BUILDER HARDWARE . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 7-1Section I Maintenance and Repair of Doors . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 7-1Section II Maintenance and Repair of Windows . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 7-7Section III Builders Hardware . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 7-20Section IV Maintenance and Repair of Hardware . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 7-28APPENDIXES

A References . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . A-1B Sample Forms for Inspecting Timber Trusses . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . B-1C Example of Typical Cost Analysis . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . C-1INDEX . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . Index-1

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CHAPTER 1INTRODUCTION

SECTION I—GENERAL

1.1.1 Purpose buildings are maintained only to the degree re-This manual provides technical guidance for themaintenance and repair of buildings and structuresat military installations. These standards shouldassist in the economical preservation of structuresand insure their continuous and efficient use.Criteria for engineering procedures to covermaintenance and repair work that is within theresponsibility of maintenance personnel.

1.1.2 ScopeThe military services are required to maintain bothrecently constructed structures and historicstructures which require special techniques to pre-serve the original appearance. In addition, someinstallations with temporary World War II era

quired to prevent further deterioration. For thesereasons, some obsolete products and their mainte-nance are discussed in this manual although theseproducts are in many cases no longer available.This manual is a technical reference document andprocedures and material selections are suggested,not mandated. This manual is not to be interpretedas superseding or negating requirements of otherpublications.

1.1.3 Restrictive Clauses (US Air Force Only)

This publication contains implied or direct restric-tive clauses. Take these clauses as recommenda-tions only.

SECTION II—DEFINITIONS

"Buildings" and "structures" are defined separately property facility for the effective utilization of itsin this section, but throughout this manual the term designated purposes. Includes work undertaken to"structures" will be used collectively to include prevent damage to a facility which otherwise wouldbuildings. be more costly to restore.

1.2.1 Buildings 1.2.4 RepairA building is a roofed or walled structure intendedfor use as a dwelling. Building is a broad term whichincludes troop housing, family housing, dining,training, medical, religious, recreational, community,administrative, technical, industrial, and storagefacilities. Specialized buildings such as hangars,maintenance docks, test cells and undergroundbuildings are also included.

1.2.2 StructuresA structure in this manual describes somethingwhich is not intended to act as a dwelling for per-sonnel. The broad term includes, sheds, elevatedstorage tanks, underground storage facilities, flag-poles, towers, walls, fences, gates, swimmingpools, and frames that support equipment.

1.2.3 MaintenanceMaintenance is the recurrent, day-to-day, periodic,or scheduled work required to preserve a real

Repair is defined as the restoration of a real prop-erty facility for the effective utilization for its des-ignated purposes, by overhaul, reprocessing or re-placement of constituent parts or materials dete-riorated by action of the elements or wear and tearin use. Includes the parts and materials and whichhave not corrected through maintenance.

1.2.5 Installation EngineerThe term "installation engineer" as used in thismanual refers to the senior engineering officer(military or civilian) serving as the principal staffofficer of the installation commander for mainte-nance and repair of real property. In each militarydepartment, the installation engineer is knownunder a different title: Navy—Public Works Offi-cer, Air Force—Base Civil Engineer, and Army—Facilities Engineer.


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SECTION III—WORK EXCLUDED

Items which are related to the maintenance andrepair of structures but not included in this manualare as follows:

1.3.1 Waterfront StructuresWharves, quays, piers, bulkheads, quay walls,breakwaters, jetties, groins, and related structuresare included in the Tri-Services manual, "Mainte-nance of Waterfront Structures" (TM 5-622,NAVFAC MO-104, AFP 91-34).

1.3.2 PaintingThe selection and application of paints and protec-tive coatings are included in the Tri-Servicesmanual, "Paints and Protective Coatings" (TM 5-618, NAVFAC MO-110 AFP 85-3).

1.3.3 RoofingThe selection, application, maintenance and repairof all types of roofing are included in the Tri-Serv-

ices manual, "Maintenance and Repair ofRoofs"(TM 5-617, NAVFAC MO-113 and MCOP11014.9, AFP 91-31).

1.3.4 Bridges and CulvertsThe maintenance and repair of all types of bridgesnd culverts are included in the Tri-Service Manual,"Maintenance and Repair of Surface Areas" (TM 5-624, NAVFAC MO-102, AFP 85-8). Inspectioninformation and ratings for all types of bridges areprovided in the manual, "Maintenance Inspection ofBridges," 1978, prepared by the AmericanAssociation of State Highway and TransportationOfficials.

1.3.5 Other ExclusionsElectrical (includes lighting), plumbing, heating,ventilation, and air-conditioning are covered byvarious Tri-Service manuals.

SECTION IV—STANDARDS OF MAINTENANCE

1.4.1 GeneralDesirable maintenance standard is the level at whicha facility can be economically maintained to protectthe Government's investment and to provide afunctional facility. Failure to maintain the facility atthis level may result in expensive repair costs.1.4.1.1 Material which are more durable andprovide a longer life may be substituted for originalmaterials provided the economic considerationsjustify the increased costs.1.4.1.2 The standards set forth in this manual arefor active and inactive installations. Specific main-tenance criteria for inactive installations, or partsthereof, are prescribed in pertinent regulations ofeach military service. See appendix A.

1.4.2 Standards for Structures1.4.2.1 Permanent, semipermanent, and temporarystructures will be maintained to provide substantially

the same capacity, efficiency, and standard ofappearance and comfort for which they wereoriginally designed, consistent with their planned useand life expectancy.

1.4.2.2 Structural components, such as founda-tions, columns, trusses, structural frames and con-nections, will be maintained regularly and in such amanner as to insure preservation and stability ofstructures.

1.4.2.3 Exterior and interior surface materials andfinishes will be maintained to eliminate defects, toprevent damage, and to keep the facility in goodoperational and sanitary condition.

1.4.2.4 The maintenance of all structures notscheduled for retention as part of the permanentinstallation will be commensurate with the planneduse and economical life expectancy of such facilities.

SECTION V—MAPS, PLANS, AND BUILDING NUMBERING

1.5.1 MapsInstallation maps and overlays showing structures,roads, electric services, and utility lines will bemaintained in accordance with pertinent regulationsof each military service. Maps are to be maintainedin a current status by careful revision and addition.Copies of these maps should be readily available tomaintenance personnel.

1.5.2 Plans

Original plans and specifications of structures con-stitute the permanent record of construction andmaterials. "Record" plans will continually beupdated to accurately record changes, additions, anddeletions. Copies of these plans should be readilyavailable to maintenance personnel.


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1.5.3 Building Numbering location and numbering of all structures will beEach self-contained structure is assigned a numberwhich is clearly marked in accordance with pertinentregulations of each military department. Then

maintained in the basic information folder or facilityhistory file.

SECTION VI—TIMELY REPAIR

1.6.1 General 1.6.4 Technical AssistanceAll maintenance personnel shall be indoctrinated Unless the cause of failure is immediately discerniblewith the importance of not only the method of and corrective measures are straightforward orrepair, but also the timely recognition and correction standard, the installation engineer, or higherof the basic cause of failure. Some portion of echelons if necessary, should be consulted for advicemaintenance is necessary due to normal wear and on corrective measures.weathering, but many failures may be traced to other 1.6.4.1 Where specific materials are concerned,basic causes. Correction of these will, over a such as composition flooring and siding, the manu-relatively short period, be justified by decreased facturer's specifications and instructions may providemaintenance as well as improved factors of use, sufficient information for corrective measures.safety, and appearance. Where there is doubt as to the cause of failure, it is

1.6.2 Causes assistance from the major command or thePremature failure of structural parts, materials, andvarious components may be caused by some of thefollowing:

a. Defective materials or structural parts.b. Incorrect installation or application.c. Failure of related, connected, or adjacent

components.d. Unusual or extreme climatic conditions ex-

ceeding the design specifications for which the ma-terial or structural part was designed.

1.6.3 InvestigationFailures occurring during the normal life expectancyof buildings and structures should be carefullyinvestigated and the fundamental defects correctedprior to superficial repair.

advisable for the installation engineer to request

manufacturer's agent.1.6.4.2 In vital structural matters or materialfailures, beyond the capabilities of or time limitationsimposed upon the installation engineering personnel,consultation and advice from qualified, privatearchitects or engineers may be obtained uponapproval by appropriate military departmentauthority.1.6.4.3 Individuals engaged in repair of architec-tural and structural elements should be aware ofelectrical (including lighting), plumbing, heating,ventilating and air-conditioning systems as theyimpact on these repairs. Specific repairs should becoordinated with other elements to insure that re-pairs do not create adverse conditions in the con-tinuance of service provided by the systems.


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CHAPTER 2FOUNDATIONS AND CRAWL SPACES

SECTION I—FOUNDATIONS

2.1.1 General a. Walls of concrete, masonry units, or brickThe foundation of a building or structure transfersthe dead and live loads of the superstructure to soilthat has enough bearing capacity to support thestructure in a permanent, stable position. Footingsare used under foundation components, such ascolumns and piers, to spread concentrated loadsover enough soil area to bring unit pressures withinallowable limits. Foundation design is determinednot only by the weight of the superstructure, butalso by occupancy, use, and the load-bearingcapacity of the soil at the site. Soil conditions maychange over a period of time and introducemaintenance and repair problems even in initiallywell-designed foundations.

2.1.2 Materials and Types of Foundations2.1.2.1 Materials. Materials for foundations are,in general, concrete (plain or reinforced), concretemasonry units (open or filled cells), bricks, cutstone, rock, and wood. Brick, cut stone, and rockfoundations are usually found only in older struc-tures.2.1.2.2 Types of Foundations. Foundations varyfrom simple walls and piers with footings to verycomplex movement-resistant walls and slabs placedwithout joints. Several basic types may be used inone structure. Due to the broad variety ofstructures on military installations, maintenancepersonnel should be familiar with a variety offoundation designs used to meet many conditions.Some typical foundations follow:

were sometimes built without footings to supportlightweight buildings on soils of high load-bearingcapacity. See figure 2-1. Refer to chapter 4, section4.3 for discussion of concrete walls.

b. A separate footing may be used under eachcolumn, or a footing may be extended continuously(spread) under a number of columns or a wall.Spread footings are required where imposed loadsare great or the soil at the site has a low bearingvalue. Footings are commonly constructed of con-crete, although brick and stone may be found inolder construction. Concrete is used plain in massor reinforced by steel rods, depending on bearingloads. See figure 2-2.

c. Spread footings and walls or piers of rein-forced concrete poured integrally are used forheavy structures, and where heavy lateral forces areexerted on one side of the wall. Examples areretaining walls, deep basements, and swimmingpools.

d. Spread footings and grade beams ofreinforced concrete may be used in large structureswithout basements. See figure 2-3. The columnstransmit the heavy localized loads to thesubstructure, and the grade beams carry therelatively light, first-story curtain wall. The spreadfootings are designed and built independently tosupport both the column loads and the grade beam.Where grade beams are above the frostline, thebottom of the beam may be V-shaped to minimizethe upward thrust of frost action on the bottomsurface of the beam.


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e. A mat foundation is one that transmits its the estimated weight of the soil removed perma-loads to the bearing soil by a continuous slab that nently in order to build the substructure must becovers the entire area of the bottom of the struc- equal or less than the dead and live loads of theture, e.g., a floor. It is used when the low-bearing structure, which is then "floating" by displacing itsvalue of the Soil results in such large isolated foot- own weight in the low-bearing value soil. This typeings that it is more logical to transmit the loads of foundation is usually designed for locationsthrough this slab to the entire area directly under where deep and heavy footings or piles are imprac-the superstructure. See figure 2-4. tical or uneconomical.

f. There are cases in which it is undesirable to g. Brick step footings and walls or piers haveallow any major increase of pressure to the soil. been used mostly in old structures. New construc-One principle that may be utilized in such cases is tion of brick foundations will normally bethat of the "floating foundation." This means that uneconomical when compared to concrete.

h. Cut stone foundations are usually cons-tructed of large blocks of hard stone (similar togranite) laid with mortar or dry joints. Newconstruction of cut stone will normally beuneconomical when compared to concrete.

i. Natural or field stone foundations are laidwith mortar or dry joints. Where stone is plentiful,it can be used economically for light structures. Itcan also be used for retaining walls and dry walls.


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j. Grill age footings have been used for light is usually pressure-treated with various types ofloads, where the bearing area required is not larger preservatives. Such footings permanently belowthan the pedestal. See figure 2-5. These footings ground-water level may last indefinitely and requireconsist of several layers of beams, normally of no maintenance.wood or steel, with successive layers at right anglesto each other and with successively deeper layers k. Piles are made of steel, wood, concrete,having larger beams. However, the rising cost of steel and concrete, and wood with concrete. Pileslabor has made these footings uneconomical. Wood are usually capped with a reinforced concrete matGrill age footings are sometimes used to support or slab. See figure 2-6. Wood piles are usuallywood posts, columns, masts, poles, and light treated with a preservative and should be totallytemporary structures. Wood used in substruc tures [and permanently] below ground-water level.

2.1.3 Inspection for Distress and Failure and alignment. Complete failure in foundations isExposed portions of foundations should be inspect-ed regularly. Inspections should occur more fre-quently where climate, soil conditions, or changesin building occupancy or structural use presentspecial problems. Evidence of incipient foundationfailure may be found during routine inspection ofother structural components.2.1.3.1 Foundation Displacement. Foundationsshould be checked regularly for proper elevation

rare. However, some settling or horizontal dis-placement may occur. See figure 2-7 and 2-8.Common causes of foundation movement includesettlement and differential settlement of the soilcaused by inadequate compaction of the soil or im-proper sizing of the footings; overloading the struc-ture; excessive ground water which reduces thebearing capacity of soil; inadequate soil coverwhich fails to protect against frost heaving; and


2-6

adjacent excavations that allow unprotected bear- placement may show up in cracked walls, damageding soil to shift from under foundations to the ex- framing and connections, sloping floors, stickingcavated area. Severe, localized foundation dis- doors, and even leakage through a displaced roof.


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Figure 2-7. CRACKS CAUSED BY FOUNDATION SETTLEMENT—EXTERIOR.


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Figure 2-8. CRACKS CAUSED BY FOUNDATION SETTLEMENT—INTERIOR.


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2.1.3.2 Material Deterioration. Foundations are derived from their shearing strength (or resistance),subject to deterioration, whether from material or which may change with ground conditions at theconstruction deficiencies or from environmental site. Clay-bearing values, for example, vary withconditions. Generally, the deterioration of founda- moisture content. A foundation on a clay site thattion materials can be determined only by direct has been laid on the basis of local standards forobservation, unless the effects are severe enough to bearing value may settle when the moisture of thecause foundation settling. Excessive moisture from clay increases (and therefore loses shearingsurface or subsurface sources is a major cause of strength), when dewatering operations are under-timber deterioration, providing the necessary taken in the area, or when an adjacent, deeper ex-condition for wood decay and encouraging insect cavation drains moisture from the foundation-infestation. Improperly seasoned wood is subject to bearing clay. Clay also loses strength when moldedcracking, splitting, and deflection. Concrete and or worked. Frost action is similar in effect to work-masonry are subject to cracking, spalling, and ing the clay. Other soil types are subject to changesettling, particularly under adverse ground and in bearing value or characteristics. Silty soils haveclimatic conditions. Steel and other ferrous metals greater capillary action than sand and, under severeare subject to corrosion in the presence of moisture winter conditions, may absorb enough water toand sometimes by contact with acid-bearing soils. form ice lenses under the footings. The mostSigns of corrosion are darkening of the metal, exposed side of a structure will have the greatestrusting, and pitting. frost action. When the ice thaws, the soil is

2.1.4 Soil Investigation The specific maintenance measures given in theIn all cases of serious foundation settlement, an in-vestigation of the bearing soil should be made as abasis for corrective action. The stability of soils is

oversaturated and incapable of supporting a load.

following paragraphs provide a partial listing ofconditions to be noted during an inspection.

SECTION II—CONCRETE SLABS ON GRADE

2.2.1 General 2.2.3 Typical Concrete Slab ConstructionConcrete slabs on grade may transmit dead and liveloads directly to the subgrade independent of theremainder of the structure (floating slab), or theymay be structurally integrated with the foundationwalls, piers, columns and footings (structural slab),so as to become a part of the structural foundation.Floor slabs on grade are normally separatedstructurally from the rest of the building. See figure2-9.

2.2.2 Types of Concrete Slabs on GradeTypically, concrete slabs on grade consist of threeprincipal types:

2.2.2.1 Plain, unreinforced, flat slabs carryinguniformly distributed light loads usually not morethan 100 pounds per square foot (lb/ft ).2

2.2.2.2 Welded wire-mesh, reinforced flat slabscarrying uniformly distributed medium loads, usu-ally not more than 500 lb/ft .2

2.2.2.3 Deformed steel bar reinforcing in flat slabscarrying heavy, uniformly distributed, orconcentrated loads.

2.2.3.1 Subgrade. Remove all sod and decomposa-ble material; backfill as required; compact andshape the surface. Backfill should be of uniformcharacter, free from large lumps, stones, frozenchunks, or material that will rot. The material se-lected for backfill should provide a density equal tothe natural density of the surrounding soil. Betterresults and greater densities can be attained byusing the backfill material at its optimum moisturecontent. In large jobs, or particularly importantslabs, the optimum moisture content should bedetermined by laboratory analysis; however, arough idea of the proper moisture content forordinary soils (except very sandy soil) can bedetermined by forming a ball of the soil by hand.Proper moisture content will result in a ball thatwill hold its shape, but not be plastic or muddywhen squeezed. Trenches for pipes, footings, utilitylines, etc., must be backfilled in layers not exceed-ing 6 inches in thickness and each layer tamped sothat the backfill will be as dense and strong as thesurrounding subgrade.


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2.2.3.2 Gravel Fill. On the subgrade, place a 4- to final resting place as possible, thoroughly6-inch layer of granular fill and cover with a vapor compacted by vibrating or tamping and spading,barrier. and screeded to proper grade for drainage. The

minimum practical thickness for a light-duty slab is2.2.3.3 Reinforcement. Reinforcement in slabs ongrade serves primarily to hold the edges of crackstightly closed and also to distribute loads that con-tribute to the load-carrying capacity. If controljoints are spaced as recommended hereinafter, re-inforcement may not be necessary. However, it ispreferable to use a nominal amount of reinforce-ment where the uniformity and strength of thesubgrade may be questionable. Such steel suppliedshould be small bars or welded-wire fabric installedat middepth of slab.

2.2.3.4 Placement of Concrete. Concrete forstructural slabs should be made with hard, well-graded aggregates and should contain not morethan the number of gallons of water specified foreach sack of cement. It should be a workable mixwhich can be placed without honeycombing orpermitting excess water to accumulate on thesurface. The concrete shall be placed as near to the

4 inches; for medium-duty, 6 inches; for heavy-duty, 8 inches or more.

2.2.3.5 Joints. Joints are required in concreteslabs to permit expansion and contraction of theconcrete due to temperature and moisturechanges, to relieve warping and curling stresseswhich result from temperature and moisture gra-dients within the slab, to minimize uncontrolledcracking caused by frost action, and as a construc-tion expedient to separate the areas of concreteplaced at different times. There are three generaltypes of joints used in concrete slabs: contraction,expansion, and construction. See figures 2-10 and2-11.

a. Contraction Joints. The initial shrinkage ofconcrete is often greater than subsequent move-ments of the slab by moisture or temperature


2-11


2-12

changes. Under normal conditions, joints are placed other debris will be removed from the joint beforeapproximately 15 to 20 feet apart, or on each installation of joint material.column line, whichever is less.

b. Expansion Joints. Expansion joints are to beinstalled at walls, columns, and machinery pads,and at 60- to 90-foot intervals. The width of jointsvaries from ¼ to ¾ inch, depending on the jointspacing and the expected temperature range. Ex-pansion joints at walls, columns, and machinerypads should be designed to allow differential set-tlement of the floors and footings. Expansion jointswill serve as contraction joints, but contractionjoints cannot serve as expansion joints.

c. Construction Joint& Construction joints areprovided to separate areas of concrete placed atdifferent times. Insofar as practicable, these jointswill be installed at the location of a planned joint.

2.2.3.6 Joint Filler Material. Joints are, with a fewexceptions, lines of complete separations of theslab. In order to keep the joint clear and free tomove, the joint is filled with an expansible material,and may or may not have water seals. The waterseals also expand and contract with the movementof the slab. Filler material is generally of two majortypes:

a. Hot or cold asphalt, tar, or otherthermoplastic or bituminous compounds, poured,placed or gunned into the joint. Cold joint-sealingcompounds, applied under pressure, are moresatisfactory for narrow joints, c to / inch wide,3

16which cannot be filled by other methods.

b. Premolded joint filler strips, manufactured ina wide variety of thicknesses, depths, and lengths,may be composed of wood, fiber, cork, spunglass,rubber composition, felt and other compressible orexpansible materials, usually with an asphalt or tarbinder (see ASTM D-1751 and D-1752). The fillerstrip is equal to the width of the joint opening, anda maximum of ¾ inch below the surface of the slab.After the concrete has set, the joint is filled to slablevel with poured asphalt (see ASTM D-1850 andFederal Specification SS-S-1401) or otherthermoplastic compounds. In areas of expectedheavy spillage of diesel fuel, jet fuel, aviationgasoline or lubricants, a jet-resistant sealant con-forming with Federal Specification SS-S-1614 orSS-S-200D will be used.

2.2.3.7 New Joints in Existing Slabs. Where newjoints have to be made in existing slabs, extremecare will be used throughout the operation. Theconcrete slab will be broken using drills, chip ham-mers or saws, depending on the extent of the workand the availability of equipment. Joints will be cutcleanly to the desired dimensions. All dust, dirt and

2.2.4 Joint Maintenance

As a general rule, joints in slabs on grades needlittle or no maintenance. If the joint is in goodcondition, it should be left undisturbed. The majormaintenance is required by the expansion jointswhere the constant movement (working) of theslab, due to the effects of temperature and mois-ture, deteriorate the joint material. If maintenanceis to be performed, all joint material should beremoved. The joint should be swept clean of alldebris, and the edges of the joint trimmed topresent a clean surface. New joint material of theproper thickness and depth should be installed.New or better joint material may be substituted forthe original material if economically feasible.

2.2.5 Special Considerations

Utility ducts and drainage trenches in slabs ongrades may be poured integrally or separately innew construction, or built into existing slabs.2.2.5.1 Ducts and Trenches. Size and location ofutility ducts and trenches will be established, inconformance with the construction drawings. Par-ticular care will be taken to see that ducts arethoroughly waterproofed. Drains will be providedto carry off any accumulation of water. Thesedrains will be separate from all other drains leadinginto a main storm sewer.2.2.5.2 Trenches. Floor drainage trenches will havemetal-grating covers and be placed to interceptsurface drainage at hangar doors, vehicularentrances, and at other locations as required.

2.2.6 Exterior Slabs on Grade

Exterior slabs on grade (i.e., vehicular entranceramps, platforms at pedestrian entrances, trans-former or equipment pads) are similar in design andconstruction to interior slabs on grade except thatthey must be supported and drained to resist frostaction, surface water, ice, snow, and otherconditions of the elements. Exterior slabs may beattached to, or be independent from, structures.Brackets, dowels, shelves, and other types of piersmay be used for support, or exterior slabs may bepoured integrally with the structure foundation towhich they are attached. Exterior slabs to bepoured independently will reply on a compactedand confined selected fill of crushed stone, gravel,sand, or cinders. In certain locales, due to subsur-face water and frost conditions, the fill bed musthave adequate drainage to prevent heaving andcracking. This drain may be connected to or be apart of foundation drains.


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2-14

2.2.7 Water Seals 2.2.9 Cement-Mortar Concrete Inlay

Water seals in joints in concrete slabs on grade are When concrete slabs become rutted, spoiled orusually of copper, other nonferrous metals, rubber broken, the entire floor should be replaced or re-compounds or plastic, and are used in conjunction surfaced. In some cases the repair may be limited towith a mastic material. There are many types and the damaged area. A cement-mortar concrete inlaydesigns, some commercially produced under pat- is the usual method of repair. For a detailedents, and others shop-fabricated from detailed de- discussion of floor repairs and resurfacing, seesigns. Because water seals are of a permanent chapter 6, section 6.3.nature, they require little maintenance. However,failure usually requires complete replacement of theaffected section. These joints are used whereabsolute water tightness is required against a hy-drostatic head, such as in swimming pools.

2.2.8 Bonding New Concrete to Existing Con- proportions of the concrete mix, and any additivescrete that might be required. Adjustments of the propor-

Proper bond of new concrete or mortar to existingconcrete surfaces is important in producing durablestructures. Lack of bond can result in leakage atjoints, unsightly incrustations, and failure ofstructures. Other methods of bonding are discussedin detail under paragraph 2.2.9., Cement-MortarConcrete Inlay, and paragraph 2.2.10., Epoxy-Resin Grouts, Mortars and Concretes.

2.2.8.1 Making Construction Joints. Where con-struction joints occur, and are not intended to beexpansion or contraction points, the surface of theconcrete, while still soft, should be swept with astiff broom or scraped to remove laitance (an accu-mulation of fine particles on the surface) androughen the surface. The surface should be leftwith some coarse aggregate projecting. Beforeplacing the next lift of concrete, the surface shouldbe free of loose particles and debris. Where laitanceis not removed before hardening, it must bechipped away until sound concrete is revealed.

2.2.8.2 Treatment of Bonding Surface. The bond-ing surface should be kept constantly wet for atleast 1 hour before placing new concrete. Timeshould be allowed for surface wetness to disappearjust before placing new material. The surface willthen be damp but slightly absorptive. A layer ofconcrete containing only one-half the amount ofcoarse aggregate should be deposited against thehardened concrete to a thickness of at least 2 Three types of epoxy-resin bonding systems areinches. This is followed by the regular mix, which available for application to portland cement con-would be carefully vibrated to prevent crete and are distinguished in ASTM C-881,honeycombing. Good results can also be secured by Epoxy-Resin-Base Bonding Systems for Concrete.saturating the hardened concrete, then spreading a Type I is for use in bonding hardened concrete,thin layer of dry portland cement about / inch steel, wood, brick, and other materials to hardened1

16thick over the surface. This should be broomed into concrete (see ACI 503.1). Type II is for use inthe surface and spread uniformly, then left bonding freshly mixed concrete to hardenedundisturbed to absorb moisture from the base. concrete (see ACI 503.2). Type III is for use inWhen it becomes tacky, the new concrete should producing skid resistant surfaces on hardenedbe placed immediately. concrete or as a binder in epoxy mortars or epoxy

2.2.9.1 Concrete Specifications. The materials tobe used to make the concrete mix will be specifiedby a qualified engineer. This specification will in-clude the quality of the cement (see ASTM C-94),the gradation of the coarse and fine aggregate, the

tions to make a workable mix will be under thecontrol of a qualified supervisor.

2.2.9.2 Mixing and Placing Mix each batch me-chanically 2 to 3 minutes, place material on slab,and vibrate, roll, or tamp it firmly into place. Agrill-type tamp can be made by nailing strips about½ inch wide and ½ inch deep, spaced about d inchapart, to the face of an ordinary tamp. Screedmaterial to designated levels and float surfaces withwood, or preferably a power float. Let stand for 30to 45 minutes or until pressure from finger ceasesto make a dent, then steel-trowel to final finish. Donot sprinkle water on it in finishing. Be careful thatfinishing does not bring any excess fines to the top.Maintain existing expansion joints.

2.2.9.3 Curing Place a suitable covering material(plastic, burlap) or curing compound (spray paint)on the new surface as soon as it has set enough tonot be marred.

2.2.9.4 Reuse of Floor. If high early-strengthcement is used, the floor can be used after 3 daysunless temperature has been below 45EF (7.3EC).In that case allow 5 days. Where standard portlandcement is used, do not use the floor for traffic loadsfor 7 days after installation.

2.2.10 Epoxy-Resin Grouts, Mortars and Con-cretes


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concretes (see ACI 503.3 and 503.4). For each pairing spalls with epoxy concretes or mortars, andtype of system, viscosity grade, temperature class, for filling saw kerfs with epoxy mortars whereand color will be dictated by job requirements as random cracking has occurred.outlined in ASTM C-88 1-78.

2.2.10.1 General. Approved epoxy-resin systems Temperature limitations of the type I and type IIprovide binding agents particularly suitable for use grout and the type I and type II binder are manda-in the type of work where a high degree of bond in tory and are repeated here for emphasis: type I isa short period of time is needed. The exceptionally for use when slab, materials, and atmospheric tem-high strengths obtainable in a very short curing time peratures are between 68E and 104EF (20E andusually permit regular traffic on the slabs within 24 40EC); type II is for use when pavements, materi-to 48 hours after the repair, depending on als, and atmospheric temperatures are between 40Etemperature conditions. The epoxy systems and 68EF (4.5E and 20EC).specified react most favorably when temperaturesare in the range of 70E to 100EF (21E to 37.8EC),but satisfactory results can be obtained attemperatures as low as 40EF (4.5EC) if properconditions are provided. The slab repairs withepoxy materials generally should not be initiatedunless the air and slab temperatures are above 40EFand rising.

2.2.10.2 Approved Epoxy Materials. Use of surface temperatures possibly plus 120EF (48.9EC),epoxy-resin systems in concrete slab repair have scheduling of repairs should be in the early morningbeen developed and numerous products for this hours, or the areas should be protected from directpurpose have been marketed under a variety of sunlight prior to initiating repair operations. Whentrade names. In selecting the materials for the slab temperatures are less than 50EF, a battery ofwork, uniformity is required for obtaining infrared heat lamps, or another suitable heat source,consistently satisfactory results. Therefore, the use should be placed over the area to be repaired for aof Federal specifications in obtaining or specifying period of about 3 hours prior to placement oper-epoxy-resin materials for the subject usages is ations. Gentle winds can make the heat lamps in-mandatory. The following issue was current during effective; therefore, temporary windbreaks shouldthe preparation of this manual: Federal be used as necessary. Raising the slab temperatureSpecification MMM-A-001993, "Adhesive Epoxy, reduces the heat loss into the slab and permits aFlexible, Filled (for Binding, Sealing, and desirable moderate heat buildup from the exother-Grouting)." This specification provides for two mic reaction occurring with the combining of thetypes of materials according to temperature two components of the epoxy system. Although anconditions: type I is for use when slabs, materials, entirely satisfactory repair can be obtained if thisand atmospheric temperatures are between 68E and moderate heat buildup does not occur, it may pro-104EF (20E and 40EC), and type II is for use when long a satisfactory cure-out or hardening andthese temperatures are between 40E and 68EF thereby delay reopening to use. Similarly, the cure-(4.5E to 20EC). The principal difference between out or hardening period for epoxy concretes and"binder" material and "grout" material is that grout mortars can be accelerated during cool weather bycontains an inert mineral filler and a thixotropic or the use of heated enclosures over the repaired area.jelling agent; the reactive constituents in both The means of attaining the desired air temperaturematerials are identical. in the enclosure must be such as to avoid localized

2.2.10.3 Applications. The general applications orintended usages of the materials furnished underthe Federal specifications are as follows:

a. Grout. The grout furnished under Federal the repaired areas of not more than 100EFspecification MMM-A-001993 may be used for ce- (37.8EC) during the hardening stage.menting dowels in preformed holes, as a bondingagent for hardened portland cement concrete, andfor grouting the cracks in pavement.

b. Binder. The binder furnished under Federal to a temperature of 70E to 85EF (21E to 29.5EC).Specification MMM-A-001993 may be used for re- When the aggregates are cold, two adverse

2.2.10.4 Effective Temperatures and Conditioning.

a. Slabs. If slabs and atmospheric temperaturesare less than 70EF (21EC) but not below 50EF(10EC), satisfactory repairs can be obtainedwithout creating an artificial environment, providedthe slightly increased cure-out or hardening periodrequired can be tolerated. Further, if the climaticseason is such that the pavement becomes hot, withair temperatures above 90EF (32.2EC) and slab

heating of hotspots since these may cause bubblingof the liquid epoxies and also induce cracking. Thesafest method is to provide circulating air withadded precautions to insure surface temperatures in

b. Conditioning of Aggregates. In the prepa-ration of epoxy concretes and mortars it is desirablethat aggregates be reasonably dry and conditioned


2-16

conditions are created. First, on addition of the sieve be held to a minimum. The permissibleepoxy material, the viscosity will be increased with maximum size selected will depend on the intendeddecreased wetting ability; second, low temperatures usage of the mortar. For example, in the filling ofof the final mixture will be conducive to a reduced saw kerfs the normal width of the cut wouldhardening rate. If the aggregates are too hot, the necessitate using an aggregate with 100 percentepoxy-curing agent reaction will be accelerated, passing the No. 8 sieve. In general, for both epoxywhich could make placement and finishing difficult concrete and mortar the maximum-sized aggregateand possibly cause cracking. should not exceed one-fourth the thickness of the

c. Conditioning of Epoxy System Components.The viscosity of the two components of the epoxysystem increases greatly at temperatures below 2.2.10.6 Sampling and Testing Epoxy Resin Sys-70EF prior to mixing with a mechancial stirring tems. All epoxy-resin materials proposed for usedevice. Although adequate uniformity of the mix- must be tested for compliance with the require-ture might be obtained at lower temperatures by a ments of the Federal Specification MMM-A-prolonged mixing time when epoxy concretes or 001993. The manufacturer's certificates of compli-mortars are being prepared, this could result in ance with the requirements should not be acceptedoverly "rich" mixtures due to the reduced wetting in lieu of tests. The samples required and the min-capability. imum quantities necessary for the tests for each

d. "Triggering" Curing Chemical Reaction. Toexpedite resumption of traffic over a repaired areaunder low slab and atmospheric temperature con-ditions, it is possible to appreciably accelerate theearly hardening rate of the epoxy binders. This may 2.2.10.7 Trial Batches—Epoxy Mortars and Con-be accomplished by scalping off the coarser cretes. Since variations in aggregate grading andfractions (15 to 25 percent of the total) of the ag- particle shape may affect the proportions requiredgregate and heating this portion of the aggregate to to obtain an economical mixture that has satisfac-about 125E to 150EF (51.7E to 65.6EC). In the tory placing and finishing characteristics, smallpreparation of aggregate-epoxy admixtures, the laboratory trial batches are desirable prior to fieldbalance of the aggregate is added to the two placement operations. Essentially, the samepreviously mixed components of the epoxy system. principles which apply for materials producedThis should give a comparatively rich epoxy onsite, such as hot-mix asphaltic concrete andconcrete or mortar mixture to allow for the portland cement concrete, will govern. In preparingaddition of the heated aggregates. Immediately trial batches the quantity of the cement concreteprior to placement, the heated scalped portion is will govern. In preparing trial batches the quantityadded with particular attention to obtaining of the epoxy binder to which the aggregate is addeduniform distribution. should be not less than 300 grams. The epoxy-resin

2.2.10.5 Concretes-Aggregates for Epoxy Con-cretes and Mortars.

a. Concretes. The aggregates used for epoxy containers should always be checked for deviationsconcretes should be' clean, dry, washed gravel or from specified proportions. A suitable capacitycrushed stone of a d or ½-inch maximum size, metal or polyethylene container having a hemi-uniformly graded from coarse to fine, and of the spherical bottom should be used as the mixingsame quality used for portland cement concrete and vessel. The polysulfide-curing agent componentbituminous mixtures. Fine aggregate and coarse should be added gradually to the epoxy-resin com-aggregate of indicated sizes meeting the re- ponent with constant stirring, and the stirringquirements of the ASTM C-33, "Concrete Aggre- continued until a uniform mixture is obtained. Thegates," should be specified for epoxy concrete mix- rate of stirring should be such that the entrained airtures. is at a minimum. Handmixing is usually

b. Mortars. The aggregate used for epoxymortars should generally conform to therequirements of the ASTM C-144, "Aggregates forMasonry Mortar." The aggregate should beuniformly graded from coarse to fine, and it isdesirable that the materials passing the No.100

layer being placed or the width of the openingbeing filled.

manufacturer's lot or batch of materials to beshipped, or retained for use by the Government, oron Government contracts, are stated in section 4 ofFederal Specification MMM A-001993.

binder normally will be a mixture of two compo-nents (2 parts epoxy resin and 1 part polysulfideplus curing agent). However, material shipping

unsatisfactory and a power-driven (air- or spark-proof), propeller-type blade should be used. Epoxyconcrete proportions by weight may vary from 6 to10 parts aggregate to 1 part epoxy binder. Aggre-gate proportions of epoxy concrete normally willconsist of about 2 parts fine aggregate to 1 partcoarse aggregate by weight. The epoxy mortars


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may vary from 3 to 7 parts aggregate to 1 part placeability and finishing properties.epoxy binder. The proportions suggested are appli-cable only to aggregates in the 2.60 to 2.80 specificgravity range. Aggregates having specific gravitiesabove or below these values will probably requireadjustment of the suggested proportions. The trialbatch procedure will assist inexperienced field per-sonnel in obtaining the proper proportions of ag-gregate and binder in preparing the larger fieldbatches. Trial batches are not necessary in the useof epoxy grout for filling cracks, placing dowels,and as a bonding medium between plastic andhardened portland cement concrete. The two com-ponents of the grout usually will be mixed in theproportions specified by the producer without theaddition of fillers or aggregate.

2.2.10.8 Field Mixing and Batch Size. Small me-chanical mixers of the drum type have been usedsuccessfully for mixing epoxy concrete and mor-tars. However, these mixers are difficult to cleanthoroughly, and delayed cleaning can result inbuildup of residual material making replacement ofthe mixer drum necessary. Toluene, the solventused, also presents problems of toxicity, fires, and-possible explosions (toluene has a low flashpoint)due to the confining nature of the mixer drum.Usually the batch size needed will be small, andhandmixing using metal pans with other appropri-ate tools will be advantageous and less hazardous.The maximum batch sizer will be limited by themanual labor capability to thoroughly mix theepoxy binder and aggregate. Experience has dem-onstrated that this will range from 200 to 300pounds total (epoxy binder and aggregate). Prior tostarting operations, the immediate onsite availabil-ity of all batch-weighted materials and the suit-ability and adequacy of mixing and placing toolsshould be carefully checked. A relatively shortdelay before adding the aggregate to the mixedepoxy binder can mean loss of the binder due to theaccelerated chemical reaction. Minor delays can betolerated provided the mixed epoxy binder isspread in a thin layer, 1 inch or less, in the mixingpan. The container and mixing sequence of theepoxy and polysulfide curing-agent componentsshould be as stated in paragraph 2.2.10.6. Themixed epoxy binder is then transferred to themixing pan or the drum of the mechanical mixer.The total amount of aggregate incorporated inepoxy concrete may be greater if the aggregates aredivided into coarse and fine fractions before beingadded to the binder. In mixing of epoxy concretethe fine aggregate fraction should be added to justbelow practicable workability (i.e., a slightly richmix) and then the coarse fraction added to thecarrying capacity of mortar while still retaining

2.2.10.9 Protection of Repaired Areas FromWeather and Traffic. Repaired areas should beprotected as follows:

a. Temperature. Pavement repairs made whenambient temperatures during the following 24hours may be 60EF (15.6EC) or lower require limit-ed protection to maintain the epoxy concrete ormortar at temperatures which will provide a rea-sonably normal hardening rate. The use of tarpau-lins supported several inches above the surface ofthe repaired area will help to maintain the desiredconditions provided the temperature difference ordrop is not too great. Heated enclosures may alsobe used to provide effective temperature condi-tions.

b. Water. The formulation of the epoxy-resingrout and binder, described in the Federal specifi-cation, is such that moisture in or on the surface ofthe slab area being repaired does not affect bondingproperties; however, free water should not bepresent. During the early hardening stages, whichmay vary from 2 to 12 hours depending on weatherconditions, the epoxy mortars and concretes shouldbe protected from the rain.

c. Traffic. The repaired areas should be barri-caded to prohibit traffic of all types until the epoxyconcrete or mortar has hardened. The time intervalover which protection against traffic should bemaintained will vary with weather conditions; but,when appropriate environment is provided orprevails, it will usually be less than 24 hours. [Note:Compressive and flexural strengths of 7,000 and1,000 pounds per square inch (lb/in ), respectively,2

have been obtained on 1.7 epoxy-aggregate mixescured at 70EF (21EC) for 20 hours.]2.2.10.10 Cleaning of Equipment and Tools. Dueto the nature of the hardened epoxy systems, alltools and equipment must be thoroughly cleanedbefore the epoxy materials set. Toluene, xylene, orother aromatic petroleum solvents hazard. In thecleaning operations the workmen must wear sol-vent-resistant gloves; and, since even the vaporswill break down natural skin oils, the use ofprotective creams is desirable.2.2.10.11 Safety and Health Precautions.

a. General Precautions. The materials used inthe two epoxy systems and the solvents used forcleanup do not ordinarily present a serious healthhazard except to hypersensitive individuals. Theymay be handled with complete safety if adequateprecautionary measures are observed. Handle onlyin well-ventilated areas. Prevent skin contact. Wearprotective clothing and goggles when possible


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contact is anticipated. Wear goggles to protect eyes any question of serious eye involvement. Cleansefrom the curing agent in the polysulfide component. all skin areas thoroughly with soap and water fol-This should be mandatory for persons doing the lowing accidental or nonpreventative skin contact.blending and mixing operations but is not so much If necessary, fresh alcohol, acetone, toluene, ora hazard for persons engaged in the placing methyl ethyl ketone may be used as a solvent;operations. Maintain good housekeeping and however, the use of such solvents should be kept topersonal hygiene standards. Remember the danger a minimum. In cases of spills, involved clothing—solvents are a fire hazard. should be immediately removed and decontaminat-

b. Personal Sensitivity. The epoxy-resincomponent presents no hazard from vaporexposure, but a few individuals have developed a develops a rash, the source of contact should berash from skin contact. Therefore, adequate determined and eliminated. Treatment of the condi-precautionary measures should be exercised. The tion should be handled by a competent physicianpolysulfide curing-agent component has an with full information furnished as to the probableobnoxious odor from the polysulfide constituent, cause.which may nauseate some individuals;consequently, inhalation of the vapors should beavoided or kept to an absolute minimum. Theamine-type curing agents incorporated in thepolysulfide constituent are caustic and may causetissue damage on direct contact with the skin.Contamination of the eye by the polysulfide curing-agent component can cause severe damage veryrapidly, and exposure to high vapor concentrationsmay also irritate the eyes and mucous membranes.

c. Personal Precautions. Although theconstituents of the epoxy systems can create somehealth hazards, proper precautions will reducethese to minimum incidence confined principally tohypersensitive individuals. Wear rubber or othersuitable impervious gloves whenever skin contactis possible. When gloves become contaminated,they should be discarded or reconditioned bywashing in appropriate solvents, followed by soapand water. Contaminated gloves, clothing, workingtools, etc., should not be removed from the workarea except for discarding or cleaning. Wearprotective clothing, such as coveralls, whenengaged in the preparation and usage operations.Wearing of contaminated clothing should beprohibited. Apply protective creams on exposedskin areas when occasional contact occurs or isanticipated. Wear full face shields or goggleswhenever droplet contamination is possible, such asduring the blending and mixing operations. Restrictblending and mixing operations to open areas, or inbuildings, to a well-ventilated hood system. Usedisposable paper coverings in the work area wheredripping or contamination is expected.

d. First Aid. Provide necessities for prompttreatment of accidental skin or eye contact. First-aid procedures in cases of accidental eye contami-nation consist of immediate and continued washingof the eye for at least 10 minutes with copiousquantities of water; bathing the eye with normalsaline solution; and referral to a physician if there is crete floors protect the surface against abrasion and

ed in the manner described herein for gloves.e. Removing Source of Contact. If a workman

f. Moving Hypersensitive Persons. Removeindividuals who are sensitive to any of the epoxysystem constituents from exposure until the condi-tion is completely cleared. Limit subsequent con-tact with materials to a degree which proves to betolerable. It may be necessary to remove highlysensitive workmen completely from the work area.

g. Obtaining Further Information on HealthFactors. Some manufacturers of epoxy resins andsome health agencies should be able to provide lit-erature and other appropriate guidance on healthand safety aspects. The Shell Chemical Corpora-tion, Industrial Hygiene Bulletin SC 106-xx (latestedition) titled "Recommendations for HandlingResins and Auxiliary Chemicals" is an excellenttreatise on many aspects of the health factors in-volved. This bulletin is readily available from any oftheir offices throughout the United States. Othermanufacturers of epoxy resins should also be ableto furnish somewhat similar information.

2.2.11 Floor Finish

For a detailed discussion of floor finish, see chapter6, section III.

2.2.12 Curing

All concrete should be kept from drying out for atleast 5 days (2 days for high early-strength portlandcement). For slabs subject to severe wearingconditions and for special toppings, the minimumcuring period should be increased to 7 days (3 daysfor high early-strength cement). Curing may beobtained by covering with waterproof paper sealedat all edges or any suitable method that will preventthe concrete from drying out. Proper curing willincrease the strength and resistance to wear andwill reduce the shrinkage and tendency to crack.

2.2.13 Liquid Hardeners

Liquid hardeners applied over friable, dusting con-


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shock caused by heavy traffic. Use low-viscosity undiluted solution of 2 pounds of crystals to 1solutions which penetrate deeply into the concrete. gallon of water. Follow same procedures as for the2.2.13.1 Preparation of Concrete Floor Surfaces.Clean all dust, dirt, foreign particles, and oil orgrease spots from concrete floors to which a liquidhardener is to be applied.2.2.13.2 Materials. Use one of the following mate-rials or an approved equivalent:

a. Sodium silicate (water glass): Commercial,40E to 42E Baume (Be).

b. Magnesium fluosilicate& Crystalline saltsplus zinc fluosilicate.2.2.13.3 Mixing and Applying Sodium Silicate.Dilute sodium silicate just before using by adding 4 On smooth-troweled floors or dense surfaces,gallons of water to 1 gallon of sodium silicate. One fluosilicate solution is less viscous and penetratesgallon of this solution covers about 800 square feet more easily.of floor surface with one coat. Apply the solutionas follows:

a. First coat Apply first coat with a mop orbroom, brushing solution continuously over floor silicate and fluosilicate solutions become about halfsurface to get even penetration. Allow at least 24 as viscous at 170EF as at 70E F (21E C). Thishours for first coat to dry and harden. Scrub dried change in viscosity is greater than that obtained bysurface with hot water to remove the glaze which diluting the solution, which is sometimes rec-generally appears, then allow 24 to 48 hours for ommended for the first coat.surface to dry completely. If floor is porous enoughto absorb first coat without leaving a glaze, hot-water scrubbing can be omitted.

b. Second coat. Apply a second coat in thesame manner as the first. Allow it to dry, scrubwith hot water, and again dry for 24 to 48 hours.

c. Third coat. Apply third coat in the samemanner. Allow it to dry thoroughly before usingfloor. Hot-water scrubbing is not needed on thiscoat.2.2.13.4 Mixing and Applying MagnesiumFluosilicate. To 1 gallon of clean freshwater add a2-pound mixture of crystalline salts of magnesiumfluosilicate and zinc fluosilicate, at least ½ poundbeing zinc fluosilicate. Fluosilicates can be obtainedas prepared solutions or as dry crystals. Drycrystals are more economical and can be mixed atthe job with freshwater in wooden vessels. Onegallon of this solution covers about 100 square feetof floor surface with one coat. Apply as follows:

seal for subsequent waxing of floors in entrances,a. First coat. Dilute the solution by adding 1gallon of clean freshwater to each gallon of solu-tion, or prepare a new solution of 1 pound of drycrystals to 1 gallon of water. Apply solution with amop or broom, and brush it continuously over floorsurface for several minutes to get even penetration.Allow at least 24 hours for drying before applyingsecond coat.

b. Second coat Apply second coat, using

first coat. Allow at least 24 hours for drying.c. Third coat. If floor is unusually friable or

porous, apply a third coat, using same solution andapplication as for second coat.2.2.13.5 Costs. Sodium silicate materials arecheaper than fluosilicates, but labor cost is greaterbecause of the hot-water scrubbing of each under-coat.2.2.13.6 Comparative Effectiveness. Laboratoryexperiments and actual use have generally shownlittle difference in effectiveness between sodiumsilicate and fluosilicate if both are applied properly.

a. Penetration of most hardeners, especiallysodium silicate, is improved by applying the solu-tion heated to about 170EF (76E F). Both sodium

b. Maximum penetration of hardener may notalways be desirable. With rough, porous surfaces itis sometimes desirable to retain enough hardener atthe surface for adequate reinforcement; use of moreconcentrated hardeners applied cold will probablygive better results. On rough or porous surfaces,42E Baume sodium silicate solution diluted 1 to 3or 1 to 2.5 is preferable to fluosilicate solution.

c. Most liquid hardeners sold under tradenames have a base of sodium silicate andmagnesium fluosilicate, with a small amount of zincsulfate, or other materials added.

d. Sodium silicate and magnesium fluosilicatewith or without added materials are favored be-cause of their availability, ease of mixing and ap-plication, ability to harden surfaces satisfactorily,and comparatively low cost.2.2.13.7 Varnish Seal Treatment. A varnish seal iseffective to prevent dusting of concrete floors thatare subjected to heavy foot traffic. It provides a

lobbies, and other areas where appearance is aprime factor. Use a sealer conforming to FederalSpecification TT-S-176. Apply the sealer liberallyby brushing it into the pores of the concrete. Afterthe sealer has been allowed to dry, buff it with afloor-polishing machine. If certain areas appearlifeless, repeat the process until the pores of theconcrete are filled.


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SECTION III—MOISTURE CONTROL

2.3.1 Moisture Damage usually necessary. The prolonged neglect of such a

The backfill around foundations is usually lessdense than the surrounding natural, undisturbedearth. Thus, the foundation area has a tendency tobe a reservoir of excess surface and undergroundseepage water, unless it is properly drained. Con-fined water builds up hydrostatic pressure againstfoundation surfaces where cracks, porosity, orvoids in joints of foundations walls will permitwater to seep into the structure and cause wet wallsand floors. It drainage is neglected for a long time,overirrigation of the bearing soil may reduce its 2.3.2.1 High Water Table. Moisture in structuresstability and lead to major dislocation of the caused by a high water table can be drained awayfoundation. Where the nature of subgrade soil re- from the foundation by installing a drainage system.sists, deters, or stops free drainage of subgrade This is usually the most effective and economicalwater, waterproofing of usable areas below grade method of maintaining dry foundation walls and(such as basements, cellars, pools, pits, vaults, slabs on grade. Two drainage systems in generaligloos, tunnels, utility trenches, and manholes) is use are described below.

condition may cause shifting or rotation of thefootings or reduction in the load bearing capacityof the soil under the foundation resulting in seriousdamage to the structure.

2.3.2 Causes and Control of Ground Water

Although there are several causes and controls forspecific ground water conditions, improved drain-age is the basic solution to the most commonground water problems. See figure 2-12.


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a. Drainage Pipe. The earth around the effective, a drain should generally be pitched fromfoundation walls is excavated to the bottom of the a high point around the perimeter of the building tofooting with enough width for working space. See a low point below the floor slab where thefigure 2-13, a foundation wall is to be exposed, connection or sump is located. Footing drainscare should be exerted to assure that the stability of connect independently of all other drains into stormthe wall and the earthbank is maintained. Special sewers, dry wells, or outfalls available for freecare should be taken in loose sand, saturated clay, drainage of water. Drains may also flow into aor a wall having an outward (horizontal) thrust sump with a float-controlled electric pump. Footingimposed upon it. Perforated or plain tile pipe or drains that connect to storm sewers or otherperforated plastic pipe such as polyvinylchloride outfalls should be designed with sufficient drop to(PVC) is installed next to the bottom of the foot- assure that the storm sewer does not flood back toing, pitched with minimum slop of ½ inch in 10 feet the foundation wall. Never connect a storm drain toin the direction of the intended runoff. Perforated a sanitary sewer. The drains shall be covered withpipe should be laid with closed joints. Plain tile pipe a bed of at least 1 foot of graded, crushed stone orshould be laid with open joints having the upper gravel. Drainpipe sizes and stone drainbed areashalf covered with a bituminous-treated fibrous (cross section) shall be determined by the estimatedbuilding paper or suitable plastic film to prevent volume of water to be drained, the length of run,sand or soil from clogging the drainpipe. To be and the slope of the drain.


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b. Gravel Drain. A stone drain bed laid at thebottom of the footings, approximately 2 feet wideand not less than 1½ feet deep, shall be installedsimilar to the draintile described above.

2.3.2.2 Roof Drainage. Where roof drainagecauses a foundation water problem, gutters anddownspouts should be installed, preferably con-nected to a storm sewer. Gutters that are improp-erly hung or allowed to become clogged will over-flow and lose their effectiveness. Leaks in guttersshould be repaired promptly. Splash blocks ordraintile should be installed in the absence of stormsewer connections to prevent pooling of waterbelow downspouts.

2.3.2.3 Surface Drainage Toward Building Thedrainage of surface water toward a building can bereversed by sloping the ground surface away fromthe foundation wall. Where that is not practical,ditching or installing drains will serve the samepurpose. The general grade of crawl spaces shouldnot be lower than the surrounding area, whichshould be graded to drain way from the building.

2.3.2.4 Infiltrating Water. Ground water underhydrostatic head will seep through minor cracks,construction joints, porous concrete, and porousmasonry. Direct leaks caused by holes, settlementcracks, complete fracture through walls and slabs,around utility pipes, conduits, ducts and other util-ity services penetrating foundation walls and slabs


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are due to improper installation of sleeves, cover. However, 6 mil (0.006 to 0.5 inch)caulking, or inserts. These leaks must be polyethylene plastic sheeting is more effective andinvestigated and repaired in conjunction with other easier to handle. The effective life of these plasticwater control measures. covers when exposed to air or under slabs has not2.3.2.5 Utility Leaks. Breaks in water, sewage,heating, and drain pipes should be repaired as soonas discovered. Such conditions will become evidentby the improper functioning of the utility involved.However, a thoroughly waterproof foundation ofslab may not show any evidence of moisture or thelocation of such a leak. If a serious break of thisnature is not discovered and repaired, it may affectthe stability and load bearing capacity of the soil.This will result in serious damage to the structure.When a break is suspected, locating the break mayrequire opening cuts in the slab or excavation of thesoil at exploratory points. After locating andrepairing the damaged utility, the foundation is tobe restored to designed conditions.2.3.3 Condensation

Condensation is caused by humid air coming incontact with cold surfaces. If it is a seasonal condi-tion, the cost of correction might not be justifiedfor the nature of the usage of the space. If the con-dition is constant and of such extent as to beharmful to the structure or render the space unus-able for its designated purpose, the conditionshould be eliminated.2.3.3.1 Condensation in Interior Spaces.Condensation in interior spaces may be eliminatedor alleviated by one or more of the followingmethods:

a. Dehumidification of room air by mechanicalmeans.

b. Insulation of walls including a vapor barrieron the warm side of the insulation.

c. Ventilation of the room to prevent the airfrom cooling to the dewpoint.

d. Where thoroughly dry conditions are re-quired, a special system shall be designed by aqualified engineer.2.3.3.2 Condensation in Crawl Spaces. In crawlspaces or “dead” areas under structures with nobasements, moisture-control problems other thanbuilding drainage develop from condensation ofmoisture rising from damp soil. The ideal methodof preventing ground moisture from entering thebuilding is to provide an impermeable vapor barrieron insulation in floors and walls. In existingbuildings, this is not practical unless it is doneduring major renovation. The most practical solu-tion is to provide a soil cover of water-resistantmaterial. In the past, 55 pound roll roofing hasbeen the most widely used and successful soil

been established. Soil covers may be rolled out onthe soil from foundation wall to foundation wall. Itis not necessary to form a complete seal over thesoil; however, at least 90 percent of the soil shouldbe covered; cracks should be limited to 1 inch.Removal of trash and debris and leveling of sharpdips and mounds in the soil will increase the life ofthe cover.

2.3.4 Moisture Control in Subsurface Structures

Moisture in subsurface structures results fromcondensation or seepage-or both. Correction mayrange from simple solutions including dehumidify-ing or using waterproof paint to drastic measuressuch as excavation and waterproofing or divertingwater sources. Three measures are used to controlmoisture: plugging leaks, eliminating causativewater problems outside the structure, and control-ling dampness inside the structure. Correction ofcondensation-related problems is detailed in para-graph 2.3.3.1.

2.3.4.1 Moisture Seepage. Seepage includes thepassage of moisture or water through masonrywalls or floors from adjacent surfaces. In mildcases, it may resemble condensation and can betested using a 12-inch square of smooth aluminumfoil taped to the masonry wall. If, after severaldays, moisture appears on the wall side of the foil,seepage is present.

2.3.4.2 Waterproof Painting. Unless cracks appearat the source of seepage, moisture control may beestablished by painting the surface of the walls witha waterproof paint. Ready-mixed paints must beapplied to a dry wall which has been prepared byremoving dirt and efflorescence with a wire brush,chipping off all loose mortar, and patching holes.The same procedures are followed for dry powderpaints, however, the wall must be wetted beforepainting. Painting is done using a stiff brush. Thepaint must be carefully worked into all pores of thesurface to seal the wall. Two coats are required andthe wall should be inspected to insure that all poresare sealed.

2.3.4.3 Water Leakage. Leakage occurs fromopenings in the walls or floors. These may includedefective joints, mortar cracks, settlements cracks,or holes resulting from damage or around pipespassing through the wall. In all cases, steps shouldbe taken to seal the opening and eliminateconditions causing the problem.


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2.3.4.4 Repairing Cracks. Leakage problems asso- 2.3.5.3 Nonbituminous Sheets. Membranes ofciated with cracks may be solved by plugging the pure plastics, thermoplastics, metal (usuallycrack using patching cement or silicone caulk as copper or aluminum), and sheathed fibrous builddiscussed in chapter 4, paragraph 4.3.6. Cement mg papers are usually applied in more than oneshould be used only in cases which show little like- layer. They are embedded in portland cementlihood of continuing shift in the structure. Hy- mortar, mastics, plastic cements, or bituminousdraulic cement must be used in those cracks where coatings. All component materials should berunning water is present. products of one manufacturer and used in strict

2.3.4.5 Exterior Moisture Control. In all cases ofleakage, steps must be taken to control the source 2.3.5.4 Cold Asphalt Application. A primer coatof moisture. This may include control of surface of thin cutback asphalt (conforming to ASTM D-and subsurface water as described in paragraph 41) should be applied to porous masonry. A heavy2.3.2, or foundation waterproofing as described in coat of asphalt mastic (conforming to Federalparagraph 2.3.4, or both. Specifications SS-A-694) should be troweled on

2.3.5 Foundation Waterproofing

If interior surface maintenance is insufficient tocontrol moisture, excavation and exterior surfacewaterproofing may be required.

2.3.5.1 Preparation of Wall Surfaces. Excavate atrench wide enough for working space around theoutside of foundation walls and to the bottom ofthe footings. Thoroughly clean the exposed sur-faces with water, detergents, live steam, or otheravailable agents. Procedures for steam cleaning aredetailed in chapter 4, paragraph 4.3.9.4. Carefullyexamine the exposed surfaces for cracks, holes,fractures, and other damage that would permitmoisture to penetrate the walls. Repairing concreteand masonry walls are outlined in chapter 4.

2.3.5.2 Bituminous Mopped-On Membrane. Bitu-minous mopped-on multiple membrane is one ofthe most positive methods of waterproofing foun-dation walls subject to considerable hydrostaticpressure. Membranes are of bituminous-saturatedfelts or fabrics. Roofing-grade, hot coat-tar pitch(conforming to ASTM D-450) or asphalt(conforming to ASTM D-312) is used to mop onthe membranes. Five plies of membrane arerecommended for hydrostatic pressures of 12 feet.All component materials used in any oneapplication should be the products of onemanufacturer, and his application instructionsshould be followed carefully. Membranes should beapplied free from wrinkles and buckles, with eachply coated completely to separate one fromanother. After the last ply has been placed, theentire surface should be mopped with coat tar orasphalt, according to membrane type (i.e., 70 lbs ofcoat tar per 100 ft and 60 lbs of asphalt per 100 ft2 2

of surface). The final coat should be protected frombackfill by a layer of fiberboard embedded in thehot coat. Care should be taken not to rip, scar, tear,or cut the finished membrane during backfilling.

accordance with his instructions.

the primer coat at least c inch thick at the rate of1 gallon per 12 square feet. Where trowel applica-tion is not feasible, two coats of asphalt masticshould be brushed over the primer coat at the rateof 1 gallon per 50 square feet per coat. On con-crete, a nonfibrous asphalt emulsion primer dilutedwith 15-percent cool water should be applied bybrush or spray. At least two heavy coats of nonfi-brous asphalt emulsion should be brushed orsprayed over the primer coat at the minimum rateof 1½ gallons per 100 square feet per coat.

2.3.5.5 Hot Asphalt Application. A coat of pene-trating asphalt primer (conforming to ASTM D-41)should be mopped or sprayed over the surface tobe treated. Coverage should be 200 to 400 squarefeet per gallon, depending on the porosity of thesurface. Two coats of hot asphalt (conforming toASTM D-449) should be mopped or sprayedevenly over the entire surface at the rate of 25pounds per 100 square feet per coat. The finishedcoat should be bright, glossy black; and dull areasshould be recoated.

2.3.5.6 Cold Coat-Tar Pitch Application. A pene-trating creosote oil-base bitumen (conforming toASTM D-43) should be brushed or sprayed evenlyover the surface at the approximate rate of 2 gal-lons per 100 square feet. Application should be re-peated until all pores and voids are filled but shouldnot exceed four coats. Each additional coat shouldbe applied at right angles to previous coats toprovide full coverage. After the last primer coat hasbeen absorbed and the surface is dry, a completebrush coat of coat-tar bitumen (80E to 100E F or26.7E to 37.8E C) should be applied at theapproximate rate of ½ gallon per 100 square feet.Areas that are not glossy black should be recoated.The finished coat should be hard and dry beforeback-filling is begun.

2.3.5.7 Hot Coal-Tar Pitch Application. A coat ofcreosote oil primer (conforming to ASTM D-43)should be brushed evenly over the surface at the


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approximate rate of 1 gallon per 100 square feet. coat composed of 1 part cement and 1 part metallicTwo coats of hot coat-tar pitch (conforming to material mixed to a creamy consistency and appliedASTM D-450, Type A) should be mopped over the with bristled brushes. The surface should be thor-primer coat at the approximate rate of 25 pounds oughly brushed to seal all pores rather than merelyper 100 square feet per coat. Pitch should be provide a surface veneer. This is followed byheated until it is completely liquid but not heated application of two coats of mortar composed of 1more than 375E F (190.6E C). Backfill should be part portland cement, 3 parts sand, and 25 poundsplaced and tamped immediately after the last coat of metallic material to each bag of cement. Thishas been applied. first coat should be troweled on and scratched

2.3.5.8 Metallic Type Waterproofing. Metallicpowder may be either mixed with water and appliedas a brush or sheath coat, or mixed with cement,sand, and water, and applied as a mortar or plastercoat. The metallic powder oxidizes and expands tofill the voids left by evaporating water. Thistreatment resists considerable water pressure.Manufacturer’s instructions must be carefullyfollowed in preparing and applying the material.Use of metallic waterproofing will be limited tointerior applications below grade where tempera-ture differences and surface movement are at aminimum. Where exterior walls are inaccessible and 2.3.5.9 Cement Plaster Waterproofing A methodwaterproofing must be applied to the interior face, of waterproofing below-grade walls is to plasterthe metallic method is recommended. Metallic-type exterior surfaces with cement mortar. This mortarwaterproofing shall consist of finely ground, clean may be made plain, or water resistance can be in-iron of carefully graduated sizes, meeting the creased by adding calcium stearate, ammoniumstandard screen analysis. See table 2-1. stearate, or other equivalent water repellent in

Table 2-1. Mesh sizes for Standard ScreenAnalysis

Standard screen mesh size Percentage retained

35 . . . . . . . . . . . . . . . . . . . . None40 . . . . . . . . . . . . . . . . . . . . 1060 . . . . . . . . . . . . . . . . . . . . 35100 . . . . . . . . . . . . . . . . . . . 50 to 70200 . . . . . . . . . . . . . . . . . . . 80 to 90

The iron shall be mixed with a chemical oxidizingagent that shall be not less than 5 percent or morethan 10 percent by volume of the total mixture. Theiron-oxide content shall not exceed 5 percent byvolume. Material shall not contain dirt, paraffin, orbitumen of more than 0.1 percent by volume. Onlyenough mortar with metallic material for immediateuse should be mixed because it should not beretempered. The wall should first be exposed,cleaned, and roughened to provide a key for thewaterproofing materials. Holes, cracks, and othersoft or porous places should be cut back to solidmaterial, cleaned, and pointed with mortar. Allpipes, bolts, and similar construction should becaulked with lead wool and waterproof cement andmade watertight. Surfaces should then bedampened with clean water and given one bonding

when partially dry. The second coat, mixed to aheavy brushing consistency, should be brushed oncarefully and floated with wood floats. Total thick-ness of all coats should be approximately / to d5

16inch. After each coat has set but not dried out,surfaces should be wetted down frequently over aperiod of at least 72 hours. Sufficient time shouldbe allowed between coats to permit thorough oxi-dation of the material. If rust color is undesirable,cover wall with one or two coats of a waterproofcement-water paint. Do not apply until waterproofcoating has completely oxidized and dried out.

amounts equal to 3 percent of the weight of thecement. Although the cement plaster method is ef-ficient, its major defect is rigidity. Structural de-fects which crack the wall may also crack thecement plaster. The method may prove adequatefor a wall which is subject only to occasionaldampness and not continuous water pressure.

2.3.6 Waterproofing Underground Structures

2.3.6.1 General. Due to the advent of numerousunderground structures (fallout shelters, commandposts, missile silos, communication centers, ammu-nition storage areas) into the military real propertyinventory, the problem of waterproofing under-ground structures has become important. A de-tailed discussion of the waterproofing is presentedusing the ammunition igloo as the model for thediscussion. The ammunition igloo is the under-ground structure most frequently encountered.However, the principles discussed are valid for anyunderground structure. Prior to initial repairs, thestructure should be carefully examined to definitelyestablish that the undesirable conditions are causedby leakage and not by condensation or othercauses. Modification of storage arrangements orphysical plant layout, improved ventilation, de-humidification, or other means to prevent conden-sation may correct the problem.


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2.3.6.2 Preparation for Waterproofing. Remove (complying with current ASTM D-1187, Type Athe earth cover from the entire structure to the over the prime coat at a rate of not less than 3[1/2]ledge of the foundation footings, including the rear gallons per 100 square feet. See figure 2-14. Applyend wall, and stockpile for replacement. When re- two plies of glass cloth fabric, which will cover themoving the earth, be careful not to damage the entire area to be waterproofed, over the freshconcrete structure or the draintile near the footings. coating of asphalt emulsion. The fabric should beScrape the concrete structure to remove all dirt, draped vertically over the barrel. Endlaps, whenforeign matter, and any loose adherent material. required, should be not less than 12 inches andRemove as much as is practicable of the old should be cemented over the lower ply. Sidelaps inwaterproofing layer if the new waterproofing is not each ply should not be less than 2 inches. Lay fabriccompatible. If the new waterproofing is compatible, vertically on the end wall and lap at least 12 inchesonly the damaged or loosely adherent portions of on the barrel for anchorage, without wrinkles andthe old waterproofing need be removed. Inspect the buckles; firmly pull into the emulsion, smooth bycleaned surfaces. Remove all sharp edges, ridges, hand to work out wrinkles, and make tight to theabrupt cleavages, bolts, and severe roughness. Fill lower walls for adhesion to prevent floating as theall cracks and openings with port-land cement emulsion is applied. See figure 2-15. Saturate thegrout. Thoroughly bond the grout to the old fabric completely by spraying asphalt emulsion at aconcrete, trowel smooth, and allow to cure. Clean rate of not less than 4 gallons per 100 square feet atall cracks, fill with asphaltic plastic cement approximately 80 lb/in pressure. Allow to dry for(conforming to Federal Specification SS-C-153) at least 2 days. Apply the finish coat of asphaltand cover with two layers of 30 pound roofing emulsion over the entire area to be waterproofedstrips (conforming to ASTM D-226) not less than using not less than 2 gallons per 100 square feet,6 inches wide, embedded in two layers of asphalt giving special attention to thin areas and areas inplastic cement c inch in thickness, centered over which the fabric is insufficiently coated. See figureeach crack. Cracks ¼ inch or more in width shall, 2-16. Inspect the coating after it has driedin addition to the above, be covered with sheet- completely and touch up any bare spots or defects.metal strips 7 inches wide, sandwiched between the Dust the waterproofed area with talc or drytwo roofing strips 8 inches wide, and heavily portland cement, using not less than 11/2 bags perembedded in asphalt plastic cement. Cracks ½ inch igloo. Lay the slip-sheet cover (complying withand larger should be filled with a mix composed of current Federal Specification SSR-501, Class A, 658 parts asphalt emulsion and 2 parts portland lb, Mica Surface) vertically with a lap of not lesscement (8:2 mix) prior to installing felt strips. Seal than 2 inches at the side. Sandbag the sheets tothe horizontal joint between the foundation and hold in place at the crown lap until the earth coverbarrel with this 8:2 mix (trowel into the joint and is replaced. See figure 2-17. Inspect the draintilespread 18 inches wide). Firmly embed a 12-inch- and verify that tile size is adequate; that the highestwide strip of woven glass fabric conforming to point is 1 to 2 feet minimum below floor level; thatASTM D-1668 centered over the joint, and coat the tile is properly laid to drain; that it is notwith a second application of the above mixture. obstructed with sediment or other objects, asRough, pitted, honeycombed areas may also be disclosed by lamping or rodding; that the dischargefilled with the 8:2 asphalt emulsion, portland is to an area with definite slope away from igloos;cement mixture in lieu of cement grout where con- and that the discharge end of tiles are screened toditions warrant. When the concrete is found to be prevent entrance of rodents. Replace the earthporous and saturated with water, dry out ade- cover carefully in two stages using procedures thatquately to provide a completely dry surface before will protect the waterproofing from damage.the prime coat is applied. Normally, the drying-out Remove rocks from the earth to the extent that itperiod is about 14 days. shall contain not more than 15-percent stone or

2.3.6.3 Application of Waterproofing Membrane.Area to be waterproofed will comprise the entirestructure, including the barrel, the rear end wall,the front wall cant, the foundations to the footings,and at least 3 inches of the footing ledge. Inspectand repair as required to provide a reasonablysmooth surface. Coat the entire surface to bewaterproofed with primer (complying with currentFederal Specification SS-A-701), applied at not dryfor at least 2 days. Apply asphalt emulsion

2

gravel, all passing a 1-inch sieve. In the first stage,replace the earth halfway up the height of the iglooand allow to settle for about 14 days, or untilnoticeable compaction has occurred. See figure 2-18. At this stage, examine the slip sheets forpossible breaks at the earth line and correct themby splicing and patching. In the second stage,replace the earth to the top of the barrel retainingwall and maintain at the same height the length ofthe igloo. Maintain a slope of approximately 1.75on 1, free of vertical and horizontal depressions.


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Maintain sufficient compaction to avoid appreciable provided with vegetation of a type consistent withslump, slippage, or shrinkage of the finish grade. the landscaping plan for the installation. RemoveBulldozers and other heavy equipment must not dirt and other foreign materials from the concreteapproach closer than about 3 feet of the igloo. apron of each igloo, and assure that the drainageFinish to grade, hand-rake, and smooth the earth to outlets are exposed and opened.provide natural drainage. The earth should be


2-28

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2-29

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2-30

Fig

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2-16

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2-31

Fig

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2-17

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2-32

Figure 2-18. WATERPROOFING IGLOO—BACKFILL

SECTION IV—CRAWL SPACES

2.4.1 General tion of moisture into structural wood and otherConsiderable deterioration extending from founda-tion to building superstructure can be caused byneglect of crawl spaces, especially in climateswhere it is necessary to enclose the space to main-tain comfortable floor temperatures. Unventilatedcrawl spaces contribute materially to rapid absorp-

materials, and the spaces soon become a naturalhabitat for fungus growth and termites. Sills,joints, and subflooring may be affected by wooddecay. Condensation may occur in the studdingspaces above the floor level and cause paint failures.


2-33

2.4.2 Housekeeping spaces should be prohibited. Crawl spaces shouldRoutine good housekeeping requires that crawlspaces be kept clean, clear, and accessible. An ac-cumulation of rubbish in the space may provide anatural harbor for insects and rodents, as well asimpede access and possibly interfere with drainage.Scrap wood is a clear invitation to termites. Crawlspaces should be checked periodically, and anadequate program of pest control carried out.Disorganized storing of any materials in crawl

be graded to prevent wet areas. Such areas breedmosquitoes, cause fungus growth, and weaken soil-bearing under footings. All ventilation openingsshould be covered with suitable hardware, cloth, orcopper screening to prevent entry of birds and ro-dents. See figure 2-19. Access doors to crawlspaces should be provided with a suitable padlockand kept closed.

2.4.3 Control of Wood Decay quate damp-proofing; wood in attics or crawl

2.4.3.1 General. Decay in wood is produced byorganisms known as fungi, which live on woodcomponents. All "dry rot" or "natural deterioration"of wood is caused by living fungi. The term "dryrot" is misleading as fungus cannot live without aregular supply of moisture. All decay destructioncan be prevented. Wood-destroying fungi requirefavorable conditions of moisture, temperature, andaccess to air. Lack of any one of these essentialconditions will inhibit the growth of fungi. Woodpresents no decay potential if it has less than acritical moisture content, is maintained at extremelyhigh or low temperatures, or is immersed in wateror coated to exclude oxygen. Warm, humidclimates or seasonal periods of high humidityprovide an environment for growth of wood-de-stroying fungi. Frequent soaking of wood members,coupled with inadequate ventilation, may produceconditions suitable for fungi growth. Unpainted oruntreated wood members, particularly those whichtouch the ground, are especially susceptible todecay. Some major areas susceptible to fungusattack are wood in contact with masonryfoundations, cold-water pipes, or air-conditioningducts; wood floors laid over concrete without ade-

spaces with inadequate ventilation; all untreatedwood in crawl spaces with standing water; lack offlashing around wall openings; wood porches,steps, columns, or posts in contact with the ground,and wooden door and window frames. Thepresence of decay is usually indicated by one ormore of the following conditions: dampness and amusty smell; warped flooring and siding; surfacecracks, particularly across the grain; fine, reddish-brown, dusty powder under the building; mildewstains on timbers; a hollow or spongy sound whentimber is tapped with a hammer, or when a sharp-pointed tool easily penetrates timber; peeling paint;and swelling joints. Results of decay is illustrated infigure 2-20. If the presence of wood rotting issuspected, contact the pest control shop.

2.4.3.2 Prevention of Decay. The best procedurein preventing decay in untreated wood is to keepthe wood dry. Air-dried wood does not containenough moisture to permit the growth of wood-destroying fungi. At moisture content below thefiber saturation point (25 to 30 percent), decay isgreatly retarded; below 20 percent, fungus growthis completely inhibited. Wood products used underadverse conditions must have a preservative treat-


2-34

ment. Decay can be prevented by eliminating d. Seal checked lumber, knots, and joints withthecauses. Outlined below are a few of the steps putty and paint.which may be taken to accomplish this goal:

a. Provide a protective seal coat to prevent that will not be accessible after assembly, such assoaking of the wood. window trim, porch decking, and doorheads.

b. Seal glass settings with putty and paint. f. Provide adequate maintenance and periodic

c. Provide tight caulking around wall openings.

e. Before assembly, paint the back of all lumber

cleaning of rainwater conductors.


2-35

Figure 2-20. CRAWL SPACE DECAY.

g. Separate all wood from earth by resting it pers in the bottom rails of screen frame and screenabove the ground line on solid masonry blocks and doors.vapor barriers.

h. Keep earth and debris away from wood, andslope the earth to drain away from walls.

i. Avoid trapping water on sills by cutting scup-

j. Keep crawl space clear of debris.

2.4.3.3 Treatment of Decay. Upon the detection ofdecay, prompt action will be taken to determine


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the extent of damage and the probable causes. If 2.4.4.3 Treatment of Termite Damage. The treat-structural members are involved, the advice of an ment of termite damage is similar to treatment ofengineer should be obtained to determine the ma- decay. The damaged members are removed and re-terials and methods to be used in effecting the placed with lumber that has been treated with arepair. The infected member may be removed and wood preservative. The assistance of an engineerreplaced with a member treated with a wood pre- may be needed if structural members are involved.servative (see Tri-Services Manual, "Military Ento- Construction to prevent the recurrence of the ter-mology Operations Handbook," [TM 5-632, mite infestation will be part of the repair.NAVFAC MO-310, AFM 91-16] chapter 8,section 5). Normally, the cause will be traced toexcessive moisture or poor ventilation. Provisionfor the exclusion of moisture and provisions foradequate ventilation should be included as part ofthe repair. The wood area adjacent to the infectedpart should be treated to insure against possiblespread of the fungus.

2.4.3.4 Carpenter Ants. Some insects such as car-penter ants are common in decayed wood. Oncethe cause for the decay is eliminated, the insectproblem disappears but the damage caused by theinsect may require repair.

2.4.4 Termite Control

2.4.4.1 General. Insects as a general rule are nota major maintenance or repair problem. However,termites are the one exception and constitute a se-rious problem in areas of infestation. Fortunately,some of the precautions effective against wooddecay are, effective in preventing termite infesta-tion. If a termite problem is suspected, contact thepest control shop for assistance.

2.4.4.2 Prevention of Subterranean Termite square footage area of the building, or 4,000 squareDamage. In subterranean termite control, it is of feet. This multipled by a of 1 percent (0.0033)prime importance to keep untreated wood dry, well yields 13.2 square feet of ventilation required.ventilated, and removed from contact with the Combining the two yields, 5.06 and 13.2, 18.26ground. Termites must maintain contact or passage square feet of ventilation would be required for ato and from the ground. Mechanical barriers, soil building size of 4,000 square feet.poisoning, and preservative treatment of timber arethe major means of combating this menace.Mechanical barriers usually are in the form oftermite shields. Unfortunately, unless these shieldsare properly installed and continually maintained,they provide little or no termite protection. Soilpoisoning, also called chemical soil barrier (see Tri-Services Manual, "Military Entomology OperationsHandbook," chapter 8, paragraph 8.15.1(8)) offersbetter protection at a reasonable cost. Chemicalsolutions are mixed with soil adjacent to foundationwalls, piers and under concrete slabs (structures c. For interior foundation walls, ventilation iswith subslab or intraslab heating/cooling duct shall required at the rate of 1 square foot per each 25not be treated until the vents are sealed and the linear feet of foundation with the requirement forsystem is reducted away from the soil). This cross ventilation.provides long-lasting barriers to termites. Woodinstalled in suspect or susceptible areas should bepressure impregnated with a wood preservative.

2.4.5 Ventilation.

Adequate ventilation of enclosed crawl spaces isnecessary to prevent decay resulting from conden-sation.

2.4.5.1 Standards. Standard guides for meetingventilation requirements include:

a. For buildings up to 5,000 square feet. Deter-mine linear footage of building perimeter and pro-vide 2 square feet of ventilation per each 100 linearfeet. Additionally, determine the total crawl-spaceground area and provide ventilation at the rate ofa of 1 percent (0.0033) of the total crawl spaceground area. Example: Assume a building size of4,000 square feet and assume the building issquare-the square root of 4,000 square feet is63.245. This multiplied by the number of sides inthe building yields 253 linear feet, or 2.53 whendivided by 100. 2.53 x 2 (the number of square feetof ventilation required for each 100 linear feet)yields 5.06 square feet of ventilation required forthe perimeter of the building. In the second portionof the equation, crawl-space area would equal the

b. For buildings larger than 5,000 square feet,determine the linear footage of the perimeter andprovide 2 square feet of ventilation for each 100linear feet. Additionally, determine the total crawl-space ground area and provide ventilation at therate of ¼ of 1 percent (0.0025) of the total crawlspace ground area. Using the procedures in theabove example, and assuming a 6,000-square. footbuilding, 21.2 square feet of ventilation would berequired for this building.

The above requirements may be reduced in arid orsemiarid climates. In severely cold temperaturezones, operable louvered vents should be closed


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during the cold season. Vents shall remain open intemperate and tropical zones or zones with highhumidity.

2.4.5.2 Installations. Crawl spaces may be venti-lated by the installation of gratings or louvers of anadequate size in the foundation walls. Small roundlouvers, which can be installed by drilling with anexpansion bit and tapping into place, arecommercially available. Vents through interiorwalls are equally important. Both types of ventsshould be installed to insure free air circulationthroughout all parts of the underfloor space.

2.4.6 Coordination with Entomology Service

Close cooperation between the maintenance serviceand the entomology service must be maintained inareas of mutual interest. Maintenance personnel

should be instructed by the entomology service inrecognition and detection of wood decay fungi andtermites. This will enable craftsmen to recognizesigns of an early fungus attack and to differentiatebetween the fungus damage and the destructiveeffects of moisture and weathering. It is advisableto make this recognition and detection part of theinspection checklist where wood structures areconcerned. Joint inspections by both services areencouraged. Investigation of damaged areas,determination of probable cause for damage, andagreement on types of repairs are joint functions.Understanding and appreciation of mutualproblems will foster a spirit of cooperation, whichwill improve the overall effectiveness of both services.


3-1

CHAPTER 3

FRAMING—STRUCTURAL COMPONENTS

SECTION I—WOOD FRAMING

3.1.1 General 3.1.2.1 Balloon Frame. The balloon frame is light,The structural components of frame buildings mustbe strong enough and sufficiently rigid to transferdead and live loads to the building foundationswithout excessive deflection or sidesway. Deadloads are those which result from the weight of thestructure. Live loads are those induced by externalforces such as wind, earthquake, snow, inhabitants,furniture, equipment, or impact. These loads arevariable. They are usually not applied over longperiods. They could be moving loads or stationary,uniformly distributed or concentrated.

3.1.2 Framing SystemThe major framing systems in use for woodenbuildings are known as the balloon frame and theplatform frame. There are modifications of thesesystems; however, the fundamental principles fallinto these two categories.

economical, and simple to construct. The sills arelaid on the foundation and anchored in place. First-floor joists are spiked in place on the sill, and thecornerposts are set in position on the sill andtemporarily braced. See figure 8-1. The studs,which run the full height of the exterior wall fromsill to plate, are spiked in position on the sill heldnear their upper end by temporary boards nailedacross them. A horizontal board called a ribbon isset into the studs and cornerposts at the properheight to form a base for the second-story floorjoists. The joists are supported in place by theribbon and nailed to the studs. The tops of thestuds and the cornerposts are sawed off level andcapped with a plate. The plate joins the top of thestuds to form a base for the roof rafters. The exte-rior sheathing is then nailed in place to brace theframe.


3-2

3.1.2.2 Platform Frame. The platform frame is end of the floor joists, and the subfloor is laid. Thismore rigid and heavier than the balloon frame. forms a platform. Next, a soleplate is laid on theLaying the sills and placing the first-story floor edge of the platform the one-story~high studsjoists are accomplished in the same manner as for capped by a plate are put in place. See figure 3-3.the balloon frame. A header is placed across the This soleplate, stud, and top-plate unit is normally


3-3

assembled in horizontal position on the platform setting diagonal braces into the studs from the silland raised as a unit. Second-floor joists are then to the top of the cornerposts to brace the walls.spiked in place on the top plate, and the entire se-quence is repeated. Sheathing is applied to the ex- 3.1.2.4 Sheathing Board. Diagonal woodenterior face. Due to the panel method of construc- sheathing has been largely replaced by patentedtion used in this system, it lends itself to prefabri- sheathing panels. These panels, which can be insu-cation techniques. lation, vapor barrier, and water repellent combined3.1.2.3 Bracing. Greater rigidity is obtained in into one unit, also provide adequate structuralboth systems by using heavier members, by install- bracing when applied as directed by the manufacturer.ing horizontal bridging between the studs, and by


3-4

damage can be inflicted on a basic building3.1.3 Sills

The inspection and timely repair of sills set onfoundation walls, posts, or columns is an importantfactor to the maintenance of any structure. As inthe case of uneven settlement of foundation, severe

structure by displacement, deterioration or otherthings which discount the ability of the sill tomaintain the upper components in their fixed, des-ignated positions. Many lesser, but troublesomeand expensive repair and replacement problems can


3-5

arise, such as wall and ceiling cracks and mis- used) are nailed to tops of posts with at least threealigned doors and windows. or more twentypenny nails. When a four-piece sill3.1.3.1 Typical Sills. Figure 3-3 shows types of is used, the additional member is nailed to thesills commonly set on posts, piers, and walls. The three-piece sill with the same size and spacings asimposed loads and pier spacings determine sill above.sizes. Built-up or laminated sills are made up of b. Solid-Timber Sill. See figure 3-3. Sills oftwo or more members solidly spiked together with solid timber should be set on posts or piers withjoints over supports, always staggered and with halved joints over supports. Nail each lapped jointcorners, as shown in figure 3-3. Note that because with three or more nails long enough to penetratedimensions and heights are measured from the in- through most of the lower half of joint. Sills are setplace sill, it is carefully cut, fitted, and laid level on level on a mortar bed. Butting ends of single sillsthe piers or wall. On concrete or masonry walls, the are toenailed with tenpenny nails. Lap double-sillsill is placed on mortar and secured with wall members at corners, and nail with ten-penny nails.anchors. The maintenance personnel should pay Anchor bolts of the appropriate size and set onespecial attention to specially framed sill corners, as near each end of each piece and at intermediateshown in figure 3-4. spaces of about 4 feet. Sills are set and secured in3.1.3.2 Sill Replacement. When inspection and en- place, as shown in figure 3-3. In balloon and bracedgineering consideration dictate that sills should be frame construction, the lower ends of studs extendreinforced, reset, or replaced, good carpentry prac- down and sit on wall sill. Studs are toenailed totices will be followed. place with two eightpenny or larger nails on each

a. Three-Piece Laminated Sill. See figure 3-3. wide fence. Joists are toenailed to sills and nailedNail from each side with twentypenny nails, two directly to studs with tenpenny nails. Subfloor isnear each end of each piece, with others spaced nailed with threepenny nails. In western or platformhorizontally not more than 32 inches and staggered framing, sills are bedded and anchored as shown innear top and bottom from opposite sides; nailing is figure 3-4. Joists and headers are set and nailed toon 16-inch centers. Stagger all joints over supports. sills. Subfloor, laid diagonally, is followed byToenail sills to posts (or caps if used) with two or bottom plate to which studs are toenailed.more nails on each exposed side. Wood caps (when


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3-7

3.1.3.3 Maintenance of Sills. Inspect wood sills Manual, "Military Entomology Operation Hand-periodically for soundness (see paragraph 3.1.4), book"), and rot. In addition, they should be kept torodent and insect damage (see Tri-Services correct grade by use of shims and mortar pointing,


3-8

and in correct alignment by reinforcing plates, extra 3.1.4.2 Corrective Measure& Corrective measurestiedowns or other means. Timbers exposed to for wood posts and columns consist mainly of theground moisture or severe weathering must be following items:treated often enough to prohibit deterioration.Measures for ventilation and other means, as pre-sented in chapter 2 of this manual, for overcomingor offsetting moisture condition must be followed,as well as general good housekeeping and safetyprocedures.

3.1.4 Posts and Columns

Posts and columns are the vertical members whichtransmit loads directly to the foundations. They arethe "legs" of the building and must be strongenough not only to transmit the vertical loads tothe foundation (sills) but also to resist lateral orside forces, such as wind and seismic forces ifpresent.

3.1.4.1 General Maintenance. Posts and columnsbelow grade or in contact with the earth must betreated with a preservative to resist decay and ter-mite damage. They should be plumb, in good align-ment, sound, and free of mold or other fungusgrowths. Make periodic and thorough inspection ofall posts or columns in contact with the ground.Areas under floors which are supported on postsshould be well ventilated and drained so thatmoisture is present only for a minimum period oftime.

a. Columns. Columns differ from posts only intheir length, and usually columns are considered tobe above grade for support of second- or upper-story floor and roof loads. In buildings which arefinished (covered with plaster, wallboard, sheath-ing, siding, and other material), it is difficult to in-spect and repair damage to columns. When it isobvious that columns are out of plumb and align-ment, covering material should be removed and athorough examination made. Failure or cracks ofcovering material may occur independently of fail-ure or movements in columns. When the possibilityof such a condition exists, sufficient covering shallbe removed to examine the columns, beams, andother structural components involved. When adetermination has been made, repair and replacecovering.

b. Posts. Inspection of posts will include a testfor soundness by jabbing the post on all four sideswith an ice pick or other sharp instrument. Theamount of penetration is the indication of itssoundness. On most softwood species, such as pineor fir, the pick should not enter more than ½ inch;for hardwood, such as gum or oak, the pick shouldnot go in more than ¼ to d inch.

a. Plumbing and Aligning. If inspectionreveals that posts are out of plumb or alignment,shore the floor above with jacks or other devices.Plumb and realign the post. If foundations are notlevel because of uneven settling, correction isrequired before any attempt is made to plumb orrealign posts or columns.

b. Seasoning Checks. Posts and columnsusually are of timber which has not been air- orkiln-dried. This results in seasoning checks whichare caused by separation of the wood fibers bydrying. Checks are not usually a cause forreplacement, but they should be carefully noted asto location, depth, and width of check. If continuedinvestigations indicate these openings or checks areincreasing in size, they should be carefullyexamined by an engineer for possible replacement.

c. Structural Failure. When inspection indi-cates that columns or posts show signs of failurefrom overloading, examination of the posts ofcolumns should be made by a structural engineer.His recommendations should be incorporated toprovide adequate repairs or replacement.

3.1.5 Floor Girders, Beams, and Joists

Girders and beams are those structural componentsof floors which span from column to column orwall to wall, and transmit vertical loads to theirbearings. These loads may be introduced into thegirders by beams, joists, planks, or other surfaces.

3.1.5.1 Seasoning Checks. Large size girders,beams, and joists are made of lumber that is notkiln dried. Consequently, it is normal to expectseasoning checks as the wood loses its moisture.Detailed inspection of these checks should be care-fully recorded as to size, location, and depth. Ifrecords indicate any increase, stitch bolts may berequired. (See paragraph 3.4.10.2 for a discussionof the proper use of stitch bolts.)3.1.5.2 Structural Failures. Beams or joists, whichhave failed in bending but have sound wood sur-rounding the failure, may be repaired by fasteningadjacent pieces (scabs) to the sides of the failedmember.3.1.5.3 Repair Consideration. There are manymethods which can be used to reinforce girders,beams, and joists. The selection of the propermethods should be determined by the loads to becarried, the costs, clearances, and accessibility.3.1.5.4 Bridging. Bridging is added to stiffenfloor-framing members (joists). Spring floors may


3-9

sometimes be stiffened by adding or repairing 3.1.6 Special Beamsexisting bridging, by adding joist, or by utilizingheavier framing. See figure 3-5.

a. Open Bridging. When bridging is in place,it is tightened by driving nails completely throughthe bridging and into the joist.

b. Solid Bridging. Solid bridging must be cutaccurately and fitted neatly between the joists toassure resistance to individual movement of thejoists. This type of bridging may also be utilized asa fire stop if correctly positioned in the floor (seeparagraph 3.1.8).

Special beams in floor frames to provide openingsare called headers and trimmers. Figure 3-6 illus-trates a method of adding structural strength to afloor opening using headers and trimmers.

3.1.6.1 Framing with Special Beams. Joists maybe framed into these members in several ways:

a. Ledger-type framing. See figure 3-7.

b. Metal joist hangar framing. See figure 3-8.


3-10


3-11

c. Metal anchor framing. See figure 3-9. consideration by given to appropriate methods of

3.1.6.2 Methods. Where joists are framed intoheaders, and headers to trimmers, the connectionsare determined by the load requirements and careexercised to minimize the effects of unequalshrinkage as much as possible.

a. Framing Anchors. Framing anchors, ifsufficient for load requirements, will provide theleast relative movement due to shrinkage, which ismost important if plaster or rigid types of ceilingcovers are used. See figure 3-8.

b. Other Methods. If other methods are usedto frame joists into headers and headers totrimmers, reinforcement and additional loadcapacity can be secured by adding ledgers, hangars,or framing anchors.

3.1.7 Workmanship

When repairs of framing and structural componentsare necessary, it is extremely important that careful

jacking and shoring in order to bring all membersinto proper alignment before corrective orreinforcing methods are applied.

3.1.8 Stops

An essential part of construction safety is themaintenance, and where necessary, the installationof fire stops. Fire stops are obstructions delib-erately placed in concealed airspaces to block pas-sage of hot gases and flames from one area to an-other. Sometimes these stops serve a dual purpose,such as for solid bridging, but in any event theymust not be inadvertently deleted during repairprocesses. Fire stops are not confined to woodconstruction but may also be of concrete, brick,gypsum, mineral wool, or other substances.


3-12

3.1.9 Other Trades tural components, it is important that repairs pro-

Where addition, alteration, rehabilitation or repairof electrical, plumbing or other utilities involvescutting, notching, or alteration of framing or struc-

vide necessary reinforcement as required by the

installation engineer.

SECTION II—WALL AND PARTITION FRAMING

3.2.1 General ribbons, which are horizontal pieces of wood

There are two general types of framing. They arewestern or platform and balloon frame construc-tion. Basic types of framing are discussed in thepreceding section. The major components of walland partition framing used in each system aresimilar and are described as follows:

3.2.1.1 Studs. The main structural elements ofwalls and partitions are usually termed studs. Theends of these vertical pieces usually bear on a hor-izontal bottom plate and are capped by a doubletop plate, as shown in figure 3-10.

3.2.1.2 Cornerposts. Cornerposts, as illustrated infigure 3-11, can be constructed in various ways.

3.2.1.3 Ledgers and Ribbons. Second- and third-story joists rest on double plates, ledgers or

supported by the studs and cornerposts.

3.2.2 Framing Maintenance and Repair

Failure of wall framing is usually related more tomajor structural faults elsewhere in the construc-tion than to defects in the framing itself. Deter-mining the best repair procedure depends on theuse of the building, extent of damage, life expect-ancy of the structure, and possible future uses.Frequently, it is possible to accept distortion,warping, and settling of the structure, and to makewall framing repairs necessary to overcomecracking of plaster, surface irregularities, stickingof doors and windows, and other localized faults.


3-13

3.2.2.1 Locating Dislocated, Warped, or Broken Any major structural repairs or replacements suchFraming Members. If some of the evidence listed as the latter should not be undertaken in load-in the preceding paragraph is apparent, tapping the bearing walls without first removing the load frominterior wall surface can be helpful in locating dis- the wall under repair by adequate shoring andlocated, warped, or broken framing components. jacking. The same precaution would apply inPlaster, dry wall, paneling, or similar interior wall remodeling activities, where new doors, arches, ormaterial will be removed and the damaged member windows are being made. Framing repairs andreplaced or repaired. replacement techniques for walls and partitions are,

3.2.2.2 Methods of Repair Warped studs can fre-quently be returned to original alignment with ad-ditional bridging. Headers, lintels, and sills can bereturned to horizontal position by proper shimming. a. Trussing and shimming.

in general, similar to the procedures used incorrecting floor-support failures. Some of themethods are as follows:


3-14

b. Split rings and shear plates.c. Yoke angles, clamps, and stitch bolts.d. Bracing and bridging.e. Scabs.f. Splicingg. Tightening bolts and renailing

3.2.3 Framing Around OpeningsAs discussed in the preceding paragraphs, framing

around openings can be directly affected by otherstructural failures. Figure 3-12 details these fram-ing components to aid in a better understanding ofrepair and replacement considerations. It is appar-ent that repair to these sections involves removingtrim surrounding wall surfaces, windows or doors,insulation, vapor barriers, and similar building components.


3-15

SECTION III—STEEL FRAMING

3.3.1 General 3.3.2 Lightweight Steel Framing

Some of the advantages of steel framing include For smaller buildings, lightweight-steel framingease of construction and freedom from shrinkage, assemblies are in common use. Figure 3-13 showsdecay, and insect infestation. a typical lightweight steel framing system. Mainte-

nance of this type of framing is primarily concerned


3-16

with tightening fittings, preventing corrosion, and and periodic inspections to check for deflected,checking for deflection and twisting of members. twisted, or damaged structural members. Except

3.3.3. Structural Steel Framing

Heavy-steel framing is used in many major build- instituting maintenance or repair measures onings and related structures. Routine maintenance is heavy-steel structural systems.limited to regular painting, tightening of fittings,

for the above procedures, the installation engineeror higher echelons will be consulted prior to


3-17

3.3.4 Steel Studs 0.021 inch with a web dimension of not less than

Steel studs are being used extensively in gypsumboard nonload bearing partitions. They comparefavorably with wood studs for the same type ofconstruction. However, steel studs offer the addi-tional advantage of being noncombustible. Thesestuds are formed from steel sheets conforming toFederal Specifications QQ-S-698 and QQ-S-700Dand are galvanized or provided with a protectivecoating. Steel studs are C-shaped, formed frommaterial having a minimum nominal thickness of

2½ inches. Larger web dimensions are availabledepending on the partition thickness desired. Steelstud flanges are not less than 1 / inches wide, with5

16each flange having a stiffening lip bent parallel tothe stud web. Stiffening lips are not less than 1/4inch wide with turned or folded edges. Some steelstuds are fabricated with preformed holes(knockouts) in the web to accommodate utilitylines. See figure 3-14.


3-18

SECTION IV—ROOF FRAMING

3.4.1 General beams and girders support floor loads. The notableRafters, roof trusses, roof beams, purlins and gird-ers support roof loads in much the same way asjoist

difference is that pitched roofs must resist lateralforces such as those caused by wind.


3-19

3.4.2 Types of Roofs the exterior walls on other trusses or columns are

Roofs can be classified in types according to theirshapes and also according to their structural limi-tations. The shapes include flat; pitched (such asshed or lean-to types); curved such as that providedby bowstring trusses or circular arches; or mansard,which is a combination of a steep-pitched andshallow-pitched roof. Roofs which are supportedon exterior walls and at a ridge or bearing at someintermediate point are usually referred to as frameroofs: Those that are truss- or arch-supported at

referred to as trussed roofs.3.4.3 Frame RoofsRafters are the structural members of a frame roof.Figure 3-15 illustrates the terminology for frameroofs. Frame roofs vary widely, from the simpleshed or lean-to type of flat roof to complicatedhipped and gabled roofs, which provide forprojections in walls which are at right angles to themain gable. Figure 3-16 shows some of thecommon types of frame roofs.


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3.4.4 Frame Roof Maintenance

3.4.4.1 Roof Rafters. Rafters are generally moreaccessible to inspection than other structuralmembers of a frame building because they are usu-ally uncovered on the underside where defects andfailures can be visually detected. Warped, twisted,or broken rafters can be replaced, or if the roofsurface is sound they may be repaired. Warped andtwisted rafters can be straightened by adding solidbridging and bracing, while broken pieces can bescabbed without harm to the roof covering.

a. Rafter Spread. Sustained overload onpitched roofs is usually manifested in spreading therafters with the consequent sag in the ridge line.Examination of the connection of rafters to theplate will be included in an inspection of roofframing.

b. Slippage. If rafters moved outward on theplate, they can be brought back to line by pullingthe ends of the rafters together with rods andturnbuckles or other devices.

c. Thrust. The same effect would be notice-able if the exterior walls were moved outward by

thrust from the rafters. This condition can beremedied in the same manner as for slippage.

d. Anchorage. Anchorage of the rafters to thetop plate is best accomplished by applying framinganchors, such as shown in figure 3-17.

3.4.4.2 Decay. Rafters, sheathing and other roof-framing members which are damaged by decaymust be replaced. One of the most prevalent causesof extensive roof maintenance is roof-framingfailure. Leaky roofs no longer protect the framing,thus allowing weathering and eventual decay.Roofs therefore will be inspected periodically andrepairs to surface coverings made immediatelyupon detection of failure. See Tri-Services Manual,"Maintenance and Repair of Roofs."

3.4.4.3 Ventilation. Areas under the roof andabove the ceiling will be well ventilated. Air ventswill be kept free from obstruction so that conden-sation does not contribute to decay of the roofmembers. See paragraph 4.2.5 for information onventilation.

3.4.4.4 Sheathing. Sheathing under the roof cov-ering should be inspected for movement, decay,


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and warping or cupping. It is sometimes necessary "Maintenance and Repair of Roofs."to redrive nails to tighten sheathing and preventcupping of the individual pieces. Threaded nails ofvarious types are useful since they have morewithdrawal resistance than plain shank nails. Whereit is necessary to renail sheathing, roof repairs willbe made in accordance with Tri--Services Manual,

3.4.5 Roof Trusses

Figure 3-18 illustrates the more common types oftrusses and indicates the character of the stress fortypical loadings.


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3.4.5.1 Flat Trusses. Most commonly used forlong spans are the flat-type Pratt trusses, withspans up to 120 feet. Both the Pratt and Warrenflat-type trusses, as well as the Howe Truss, arecharacterized by relatively high stress in the webmembers in relation to the chord member stresses.

3.4.5.2 Bowstring or Curved Trusses. Bowstringtrusses are generally found in the smaller hangars,warehouses, and some recreational buildings. Thesetrusses are characterized by relatively high chordstresses with the web members carrying

proportionally lighter stress. The upper chords ofbowstring trusses are generally of laminated con-struction. Failures will be found more often in thechord members. However, this type of truss givescomparatively less maintenance trouble than othertypes.

3.4.5.3 Pitched Trusses. Pitched trusses of theFink, scissors, and related types are used for shortspan, usually 60 feet and under. They are found inrecreational, chapel subsistence, garage, barracks,and similar type structures.


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3.4.6 Timber apart sufficiently to insert a knife or spatula blade

Expensive and unnecessary repairs or replacementsare sometimes made on timber members that, g. Saw Kerf. An artificial, predetermined splitdespite extensive seasoning, still retain the full of limited length made by sawing through parallelload-carrying capacity for which they were to the axis of a piece, thus preventing uncontrolleddesigned. To properly evaluate the effects of location and direction of a possible natural split orseasoning, a full understanding is required of timber check. Purpose is the same as a contraction joint inbehavior during seasoning, timber construction concrete.practices, and the designer's allowances for thesefactors.

member which is loaded axially in compression.3.4.6.1 Definitions.

a. Check: A surface opening caused byseasoning, which does not extend through thethickness of the piece and follows the grain. Severechecking appears as a series of discontinuouscracks progressing from one wood-grain layer toan adjacent layer with none of the separationsextending to the other side of the piece. A check isnot a matter of concern unless there is a possibilityof becoming a split in a critical location. Do notrefer to checking as "cracking."

b. Split: An opening which has separated thewood, extending from one surface through thepiece to the opposite surface or to an adjacent sur-face. A split is of most concern when it extendsfrom the tension face of a beam bottom of beam inbeam- and post-type construction); or, if the splitpasses through the bolt or connector area in a trussmember. Do not describe the condition as"splitting."

c. Shake: A separation along the grain, mostof which occurs between the rings of annualgrowth. For practical purposes, treat a shake as aparticular type of split.

d. Stitch bolt: A small bolt (generally d- or½-inch diameter) placed in a member to prevent en-largement of checks or splits. Stitch bolts shouldnever be used to close a check.

e. Bolt Area: Area bounded by a line ¼ inchoutside the bolthole and extending through thethickness of the wood member, not to be confusedwith the bolt-bearing area. In bolts withoutconnectors it may be considered as the areacovered by the bolthead or nut and washer.

f. Connector Area: Area bounded by a linearound the bolt equal in diameter to the diameter ofthe connector and extending through the thicknessof the wood member. Since properly installedconnectors cannot be seen, reference must be madeto structural detail drawings to determine the size.If drawings are not available the size may bedetermined by loosening nuts and prying members

and measure them.

h. Compression Member: For purposes ofthese data a compression member is defined as a

i. Tension Member: A member which isloaded axially in tension.

3.4.6.2 Lumber Grading. Lumber is inspected atthe mill and strength graded according to visualcharacteristics, such as knots, shakes, splits,checks, holes, decay, and slope of grain. Workingstresses for strength grades are assigned, which in-clude appropriate downward adjustments of clearwood stresses to make allowances for sizes and lo-cation of knots, slope of grade, shakes, checks andsplits permitted in the particular grade. In general,the working stress for the structural grade oflumber specified has made allowance for checksand splits normally expected throughout the life ofthe piece. These allowable working stresses may beobtained from the "National Design Specificationsfor Wood Construction," published by the NationalForest Products Association.

3.4.6.3 Seasoning. Lumber may be either kiln-dried or air-seasoned. Kiln-drying minimizes devel-opment of checks and allows selection of pieceswith extent of checking predetermined. Kiln-drieddimension lumber in small sizes (4-inch or lessthickness) is readily available and usually used.Large-sized (4-inches and up) kiln-dried lumber isusually not available except on special order andafter considerable delay. Consequently, large-sizedlumber is often installed green and allowed to air-season with large checks and splits being common-place.

3.4.6.4 Checking. Checking most adversely affectsthe strength of lumber when checks are located atthe ends of the piece within the middle third of thedepth of a piece used as a beam. Such checkingweakens the beam's resistance to horizontal shear.However, horizontal shear only becomes a designconsideration in short and relatively thick beams.Another adverse effect occurs when checking is ata steep slope near the tension face of a beam. Suchchecking reduces the beam's resistance to tensionand, if not arrested, could develop into a split.Normally checks are of relatively little importance;their seriousness is a factor only in bending action


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or in the probability of developing into a split and posed wood fiber or flaking of paint or other finishthe relative importance of a split in that location. material. Measurements should be taken and theAppearance alone should not be the deciding beam monitored to determine any additional de-factor. The function of the member is the prime flection. If it is determined that creep has occurredfactor. Since most members of trusses are designed and the roof deck must be leveled, it should be ac-for axial loads only and not in flexure, checking complished by shimming between the beam and themay largely be ignored (unless usage or design roof deck.shows the member to be in flexure). Only splitsextending through bolt or connector areas need beevaluated.

3.4.6.5 Shakes. Shakes occurring in the connectorarea which might result in separation of a portionfrom the rest of the piece should be investigated forrepair. Other shakes may be disregarded as suchand be evaluated as a check or as a split.

3.4.6.6 Splits. Splits occurring in compressionmembers, such as columns, may be serious if thereis no probability of slippage from wedging action ofconnectors or bolts and if the split appears to bedividing the member completely into two parts,thus increasing the length-to-depth (lid) ratio. Splitsextending into the bolt or connector area of tensionmembers should be investigated and measure. Allmeasurements of split openings should be made atthe distance from the bolt, which is the requiredend distance for the size of connector used. Excessend distance should be ignored. A single splitwithin the connector area, up to / -inch opening3

16of the splits for a connector of 2e inch or less anda split of ¼ inch for connectors more than 2e inchup to 4 inches, may be disregarded. Splits openedup more than of these widths should receiveremedial action to curtail further splitting. If thereis more than one split in the connector area, thetotal opening of the splits should not exceed 1½times that for one split. Splits may be repaired byuse of stitch bolts provided that the cross-sectionalarea removed by boring does not exceed the cross-sectional area occupied by the maximum-size knotpermitted in the structural grade of timber used.Clamps consisting of small angles and pairs of boltsalongside the member at the split may also be used.Care should be exercised in tensioning both stitchbolts and clamp bolts snugly. No attempt should bemade to close a split or a check as this may causeit to extend on the other side of the joint.

3.4.6.7 Sagging Beam. Sometimes a saggingtimber beam will appear to be overloaded when itis really not overloaded. An inelastic deformationcalled creep will give an appearance of excessivedeflection at the midpoint. Damage might occur ifsuch a beam is jacked back into a level position.The beam should be checked first to find out ifthere is any evidence of recent motion. In a realoverload, there will be fine breaks revealing unex-

3.4.7 Defects

Discussed below are typical causes of defectsusually found in roof trusses. The discussion ismainly concerning wood trusses, since these trussespresent the majority of the roof truss problems.

3.4.7.1 Defective Material. All lumber incorporat-ed in the trusses should be carefully checked duringinspection. A record should be kept of the memberscontaining an excessive number of knots so thatparticular notice can be made of those membersupon subsequent inspections. Specificationrequirements for structural grade material are thatknots will be sound, tight, and not in clusters. Thesize of the knots should, of course, be limited. It isrecommended that the installation engineer acquire,for reference, standard grading rules as published inpamphlet form by the lumber industry for use indetermining the quality of material incorporated inthe trusses.

3.4.7.2 Poor Workmanship. Poor workmanship isevidenced in many ways. Some of the conditionsthat have been encountered in the past are outlinedbelow for particular emphasis. Lack of precision indrilling boltholes and cutting grooves for timberconnectors will cause inadequate gage, edge, andend distances that may reduce the strength of thetruss. In some instances the grooves for the timberconnectors, although required on one side only,were cut for split rings when it was necessary touse shear plates. Then new grooves were cut whichresulted in too much material being removed andthe timber not bearing along the exterior rim of theconnector. Both the above conditions couldweaken the truss and should receive furtherinvestigation. Instances were discovered whereholes had been drilled for bolts that were neverinstalled. In other cases, bolts of a smaller diameterthan the drilled holes were installed. In both theabove cases, the correct bolt should be inserted;however, care must be exercised in supporting thetruss and binding the joint before removing theundersized bolt. Quite often bolts have been usedthat were too long or too short. If a bolt is tooshort, the head of the bolt and the washer mayrecess into the member, which reduces net area.When a bolt is too long, it may be impossible totighten the nut enough to obtain a snug connection.


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This condition, however, can be remedied by the truss is in distress and remedial measures areremoving the nut and installing additional washers necessary. The structural detail drawings will indi-as fillers. Washers on too small an area or thickness cate the existence of timber connectors (which arehave been used between bolthead and timber, normally concealed) as well as the type and size,resulting in a crushing of fibers or a dishing of the which will aid in evaluating the seriousness of anywasher. In cases of unusual checking or settlement splits found in the onsite inspection.at particular panel points, an inspection should bemade to determine if any timber connectors havebeen omitted. Conditions may be discovered wheretimber connector grooves have been cut too deepor too shallow. Both conditions are serious andshould be investigated further. Many instances havebeen observed where the ends of the web membershave been cut off flush with the underside of thebottom chord. In some cases this was done so thatelectric conduits or other mechanical fixtures couldbe attached to the underside of the chord; in othercases, it was done to increase the ceiling clearance,particularly in garages where the members were inline with entrances where trucks were likely topass. This reduction of end distance is detrimentalto the truss and, in addition to weakening the truss,makes it difficult to repair excessive splitting of themember by installing stitch bolts.3.4.8 Inspection

Timber trusses should be inspected at least onceeach 2 years. More frequent inspections may be di-rected by the individual military departments forspecific facilities, such as commissaries, theaters,gymnasiums, exchanges, dining halls, and placeswhere large crowds assemble. Appendix B containsseveral suggested formats which may be used asforms to aid in the inspection process. The first isa data sheet which will remain unchanged untilalterations are made to the building. Larger eleva-tion views and photos should be used when neces-sary to monitor serious defects. A checklist willremind the inspector of items to inspect. A simpleform may be used for routine annual inspectionswith minor defects described on the reverse side.Examples of these non-compulsory formats not re-quiring reporting are included. Visual inspectionfrom the floor, even with the aid of binoculars, isnot enough. The following inspection procedure issuggested.3.4.8.1 Checking Existing Construction. If possi-ble, obtain the latest revision of the structuraldrawings of the truss and verify if the existingstructure conforms with the drawings. Significantdeviations or alterations should be reported so thatthe changes can be analyzed structurally and therecord drawings updated. No attempt should bemade by the inspector to correct apparentconstruction deficiencies unless structural analysisindicates that correction is advisable or if subse-quent inspection reveals movement indicating that

3.4.8.2 Terminology. The inspector should famil-iarize himself with the proper timber terminologyand use it in his reports. Timber terms are definedin paragraph 3.4.6.1.3.4.8.3 Overall inspection of entire truss. Examinethe truss from the floor to determine if there is:

a. Obvious failure of truss, which would makean inspection from the truss itself unsafe.

b. Lateral bowing of upper or lower chordswith respect to truss support points. A truss that islaterally bowed indicates that lateral support iseither nonexistent or nonfunctioning. Further ex-aminations must be made of bridging, X-bracing,struts, purlins and deck to determine if slippage isoccurring in a connection.

c. Vertical sagging of frame (subsequent studywill determine if sagging is normal deflection due toloading, long-term creep, or partial failure of anoverloaded member).3.4.8.4 Detailed inspection. Examine the truss atclose range from a ladder, lift machine or from thetruss itself to determine the following:

a. Rupture of any member.b. Evident separation of sides of members at

joints. Nuts should be snug enough to prevent sep-aration of members without embedment into thewood. Loose or absent nuts are detrimental whenthey permit the timber members to separate andrender the shear connectors less effective. Missingnuts should be replaced and all nuts tightened tosnugness without embedment into the wood.

c. Noticeable bowing or warping of anymember. Bowing could indicate an overloadedcompression member; however harmless warpingmay occur in an unloaded redundant member.

d. Continued development of checks(nonthrough cracks) toward line of bolts.Progressing checks are indicated by freshly exposedwood surfaces at ends of checks. A checkprogressing toward a bolt or connector area shouldbe monitored so that corrective action can be takenbefore it becomes a split.

e. Development of splits through a bolt areaor connector area of web joints or chord splices.

f. Evidence of leakage such as waterstains,mold, or decay.

g. Wood crushed by overtightening of bolts.


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h. Wood fibers freshly exposed by flaking 3.4.9 Timber Roof Maintenance.paint or preservative.

3.4.8.5 Inspection of Ancillary Member. Examineother members attached at right angles or providing roof framing.support to the truss to determine if there has beenany movement. These may be:

a. Beams or purlins supported on the top ofthe top chord. These may be secured by nails "toe-nailed" into the top chord of the truss. Any move-ment will result in the nails bending at the memberinterfaces and the members may disengagecompletely. If purlins had been installed with boltedclip angles on top of the truss or recessed into sidesof top chord with steel hangers, such movementwould have been almost completely eliminated.

b. Struts installed across tops of bottom chordshould be examined in the same manner as pur-lins.

c. X-bracing members serving as sway bracingor bridging should be examined to determine ifconnections provide positive support to maintainvertical alignment of truss. The truss designer maybe provided lateral bracing by another means but,nevertheless, the absence of X-bracing should benoted in reports.

d. Purlins, beams, and struts should be exam-ined for freshly exposed wood where member ex-tends into expansion joint pocket at firewall.

e. Purlins, beams, and struts abutting wallsand chord fastened with clip angles or hangersshould be examined for bowing or freshly exposedwood fibers indicating member has been subjectedto unusual loads.

f. Masonry unit walls, columns or pilasterssupporting trusses and concrete piers supportingtimber columns must be examined for deterioration.The presence of cracks in brick or mortar adjacentto the bearing plate must be noted. Recentmovement is indicated by vertical edges of bricksbeing out-of-line, corners of brick or concretebroken, cracked brick, and other exposures of un-weathered brick or concrete.

g. Timber columns, knee braces and columncapital must be examined for damage created bymoving vehicles as well as the other defects dis-cussed above. Special note should be made of anylarge foreign items installed on columns or anynotches or cutouts made to accommodate any typeof equipment. Many times such attachments con-ceal deterioration in the column underneath.

The following paragraphs describe maintenanceprocedures which should be followed for timber

3.4.9.1 Bolt Tightening. It is important that alltruss connections receive periodic tightenings untilthe moisture content of the lumber reaches a stateof equilibrium with the atmosphere. It is also im-portant that, during the first year, the connectionsbe tightened at frequent intervals to prevent theconnections from becoming excessively loose, re-sulting in settlement of the trusses, excessive split-ting caused by the introduction of abnormalstresses, and, in extreme cases, failures in trussmembers. There are a number of corrective meth-ods for repairing damaged members. The types offailures, near failures, and other unsatisfactoryconditions encountered vary and require a differentapproach in practically all cases. Bolts should besnug but not overtightened to the extent to causedamage to the timbers. Listed below are typicalrepair and maintenance operations as performedunder the bolt-tightening program.

a. Truss bolts will be tightened as soon as theybecome excessively loose. Bolts may be consideredloose if, after striking the bolthead a sharp blowwith a hammer, the nut can be taken up two fullturns or more. Actually, this condition would notcause concern when there are a number of membersmeeting at a connection, if the actual reduction ofbearing area on the connectors were the onlyconsideration. However, a looseness of bolts at allconnections reduces the rigidity of the truss as awhole. The character of the timber trusses is suchthat there is a certain eccentricity to the lines ofstress, and such looseness would tend to increasethat condition.

b. Climatic conditions determine the rate atwhich shrinkage occurs. In the northeast, for ex-ample, the summer season is warm and moist sovery little shrinkage is likely to occur. During thewinter months when the air is normally less humidand the buildings are heated, the relative moisturecontent of the atmosphere is greatly reduced.Consequently, it is unlikely that any appreciableshrinkage will occur from May to October in thatarea. During the remaining period, a closer checkshould be kept on trusses. Climatic conditions varyin different sections of the country, but require thesame general consideration as outlines above.

c. While performing a routine bolt-tighteningoperation, the bolts should be checked to determineif there is sufficient thread to tighten the nut. Alsocheck the size of washers; if they are so small that


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the truss members cannot be drawn together with- destroying that fiber and cupping the washer.out embedding the washer, they should be replaced Effective tightening of bolts should be accompaniedwith larger ones. Where it is impractical to remove by tapping on members and boltheads. It isthe bolt to place a new washer next to the bolthead, especially important that bolt tightening bea square, slotted washer may be inserted between performed upon completion of a structure, and thatthe existing washer and the wood. Wherever frequent inspection and additional tightening beslotted washers are used, a nail should be driven performed during the year following construction.into the timber at the edge of the washer, A few drops of oil placed behind the nut willprotruding sufficiently to eliminate the possibility of facilitate tightening of bolts having rusty or dirtythe washer turning and falling off in the event of threads. It is recommended that each bolt, afterfurther shrinkage of the timber. All washers should tightening, be keel-marked for inspection purposes.be at least ¼ inch in thickness and not less than 2 It is further recommended that date of tightening beinches square. When tightening nuts, the bolthead stenciled on one of the trusses of a structure toshould be struck sharply with a hammer to force keep the importance of this maintenance workthe bolt through the truss member and break any firmly in the mind of inspectors.adhesion between the bolt and timber resultingfrom corrosive action.

d. Under those conditions where there is whether or not the corrective bolts are in the holesinsufficient thread to draw the timber tightly drilled for them or whether any bolts have beentogether, a filler washer of some type is required. omitted. In such cases, bolts should be replaced orUsually these bolts extend at least 2 inches beyond installed. If timber connectors, such as shown inthe nut. A short compression spring has been used figure 3-19, have been omitted at any joint or ifwith excellent results as a filler, which, in addition, there is visual evidence of excessive stress at themaintains a tight connection, thus reducing the joint, repairs should be made and the proper boltsfrequency for future tightenings. These spring and connectors installed while the truss is fullywashers should, therefore, be considered when pre- supported at the panel points and clamps are re-paring for a first tightening of any truss. The bolts lieving the joint of all stress. The condition of theshould be checked to determine the amount ex- joint should be recorded and special observationstending beyond the nut after they have been tight- made upon subsequent inspections. Precautionsened; if the extension is sufficient, the springs should be taken so that additional loadings, such asshould be installed. The springs that have been used hoists and monorails, will not be applied to thoseare of round edge, / -inch by ¼-inch section, and panel points.7

16of two to three coils. The pressure exerted whenfully compressed is approximately 2,800 poundsand there is a straight-line reduction as it expands.This pressure compares favorably with theallowable compression stresses perpendicular to thegrain.

e. In many structures, inspection reveals thatbolt tightening is required due to shrinkage alone.As a general rule, bolt tightening should be per-formed if the average takeup on nuts is more thantwo turns. This, of course, is quite arbitrary anddepends greatly on the size of members and lengthand size of bolts. The importance of keeping boltstight cannot be overstated. Design values arepredicated upon tight connections. In a bolt-tight-ening operation, care should be exercised to seethat the men have safety belts, if necessary, to workfrom a hazardous height. Spud wrenches of theproper size are used in order that uniform leverageand takeup may be obtained in all bolt-tighteningoperations. The use of slotted washers isrecommended as fillers. It is important that bolts betight, but too much leverage on the spud wrenchmay force the washer into the fiber of the wood,

3.4.9.2 Omission of Ring Connectors and Bolts.At the time of bolt tightening, it will be noted

3.4.9.3 Roof Settlement. As roof truss connectionsbecome loose, roof settlement occurs. While thissettlement might not be of concern to the structuraladequacy of the truss itself, problems may developin other areas requiring remedial action.

a. Roof Drainage Systems. On structurescontaining parallel chord roof trusses, anysettlement will seriously affect the roof drainage.Usually a wood truss is fabricated with severalinches of camber, a considerable portion of whichremains after the installation of the roof deck,roofing, and other dead loads. The roof slope forproper drainage is predetermined, and the roofpurlins are set on shims or blocks to acquire thatslope. As the truss connections become loose dueto shrinkage of the lumber, the trusses sag and dropbelow the horizontal. This, of course, removes thepossibility of rainwater draining from the roof andso increases the live loads to which trusses aresubjected. It has proved to be almost impossible toreplace a camber in a truss. Consequently, jackinga truss prior to a bolt-tightening operation will beof little value. Instead, the roof purlins must be


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raised from the top chord of the truss and shims methods of repair and standards to be used. Typicalplaced between the purlins and chords. Perform all examples of actual conditions found and repairedjacking directly from the truss; otherwise, the are presented.removal of the roof loads from the truss will onlycause the truss to rise with the roof. In order tojack the purlins, short timbers should be set on thebottom chord of the truss perpendicular to thechord and directly under the purlins to be raised.The purlins should then be jacked cautiously so thatthere will not be an abrupt rise in the roof to breakthe roof covering and cause leaks. This workshould be performed during the summer seasonwhen the roofing is pliable.

b. Binding of Doors. Where roof settlement of Eight-ton jacks may be used under the shores.a hangar occurs at the door guides, which were Shores themselves may be of steel or of seasonedoriginally set with provision for approximately 3 timber. Sufficient planking should be placed underinches of adjustment, a binding of the doors is in- jacks to distribute load on the floor. Trusses shouldevitable. The procedure for adjusting the door be raised slowly and carefully, jacking each shore inguides, of course, depends upon the design of the small increments at any one time. Otherwise,canopies and guides. additional failures. may occur, due to secondary

3.4.10 Timber Roof Repair

The following paragraphs illustrate and discuss

3.4.10.1 Shoring. It is frequently necessary toshore trusses to prevent collapse or to provide se-curity while making repairs. Figure 3-20 indicatesproper locations for shoring typical trusses. Shorescan be placed at all panel points if desired. Themethods shown indicate the minimum number ofshores necessary to properly support typical truss-es. In shoring Warren-type trusses, it is advisable toplace a temporary strut to prevent introducingserious secondary stresses in the truss members.

stresses and distortion, and damage may be done tothe roof membrane of the structure. Both judgmentand experience are required for this operation.


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3.4.10.2 Split and Checked Members. As used. Checks and splits are normal reactions inpreviously stated, the standard practice of using most timber as it dries out, and it is moreunseasoned lumber for trusses invites checks and pronounced in certain types of lumber. In thosesplits in the members when unseasoned lumber is members that have only one row of bolts, any


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check or split that occurs is normal and is not likely ends must be returned to their original position.to be serious. However, if the split passes through This requires simultaneous shoring of the truss andthe boltholes and continues beyond into the axial tension jacking of the member.member, it requires attention. The recommendedremedy for such splitting and checking is theinstallation of stitch bolts in the ends of each suchmember that has split. The bolts used for thispurpose are ½-inch bolts, threaded on both ends;/ inch holes are drilled 2 to 4 inches from the end916

of the split member and perpendicular to the axis ofthe member. The bolt is then inserted and 2-inch,square-cut washers are place at each end and thenuts are tightened. It is advisable to install the stitchbolts prior to tightening the bolted connection. Ifthe split is serious and continues well into themember, a second stitch bolt should be placed onthe opposite side of the connection about 6 to 12inches from the ring connector. Usually, this oper-ation will not reduce the net area enough toweaken the member. In some cases, when the splitpasses through the connection but does not pass d. In cases where checks and splits have oc-too far up into the member, it may be stopped by curred in tension members, with excessive slope ofdrilling a small hole through the thickness of the grain, it may be possible to close the split or retardmember at the end of the split. This hole will further development of the split by placing stitchrelieve any abnormal stresses at that point. Care bolts or clamps along the member at strategicmust be exercised in drilling stitch boltholes so that points. Stitch bolts, however, should be installedholes are parallel to the face of the member. Ship only after careful consideration, for the excessiveauger bits tend to follow the grain and stray from use of stitch bolts between connections is notthe intended centerline path. Metal-type fluted drill desirable and may weaken the member if installedbits with extended shafts are more effective in indiscriminately.drilling straight holes.

3.4.10.3 Damaged Web Members (Tension). Quite The usual types of failures in compression areoften an inspection of truss members will indicate either a shear along the fibers when the slope ofthat certain members may not be of structural grade grain is excessive or a bowing of the member thatmaterial because of the slope of grain is excessive, may or may not result in breaking of the fibersor the members may contain either an excessive perpendicular to the grain. It is recommended in allnumber of unsound knots. These conditions will cases that the damaged member be repaired byweaken the members, especially those in tension, placing a timber of similar width and depth adjacentand in the case of unsound or excessive knots will to the damaged member, connecting them withreduce the net area of the members. In the event bolts and split-ring timber connectors. If the failurethat the condition appears critical or an actual is close to the panel point, splicing the member mayfailure has occurred, it will be necessary to not be practicable. Installing a new member on thereinforce or replace the member. same plane would then be advisable, with the

a. Replacing any truss member can be a costlyoperation. Unless the building is for permanent use,it is recommended that the member be repaired oraugmented rather than replaced. The leastcomplicated procedure is merely to shore the truss 3.4.10.5 Damaged Chord Members. Failures indirectly under the damaged member. This bottom chord members occur as the result of ex-procedure should, of course, be followed only if the cessive slope of the grain, knots, or other defects infloor space is not a consideration. the material. In most trusses, the chords and most

b. When a tension member fails, settlementmay occur in the truss, and the ends of the memberat the point of failure may become separate. If themember is to be repaired by splicing, the separated

c. A second and more satisfactory procedureis to prepare steel rods with a steel plate welded toone end and the two rods connected by aturnbuckle. The plate at the end of each rod isdrilled in the field to fit the existing bolts at theconnections at either end of the damaged member.Grooves are cut into the outer face of the top andbottom chord for shear plates and the connectorsand plates installed. CAUTION: Grooves for shearplates are cut with a tool utilizing the existing boltholes as alignment guides for the groove cutters.Before bolts are removed for this purpose,adequate shoring and tension jacks must beinstalled. The turn-buckle can then be taken upuntil the web member is returned to its originalposition.

3.4.10.4 Damaged Web Members (Compression).

chords connecting the new member to the existingbolts with shear plates and steel gusset plates. Thenew member should then be securely fastened tothe damaged member with bolts and split rings.

of the web members are made up of at least twotimbers. This allows a certain safety factor: if onetimber fails, the other will temporarily carry theadditional load. It is likely, however, that under thatadded load the other member would eventually fail


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unless the failure is discovered at an early date. removed. Using the damaged member as a templet,Periodic inspections will uncover such conditions the new member can be fabricated and installed.before failures occur in adjoining members. The replacements should be of the same material as

a. Checks usually occur parallel with the grainof the timber. Checks and splits may be morepronounced at panel points containing two rows of f. If only partial failure has occurred, thebolts that restrain the normal shrinkage action and chord may be repaired by installing timber splicesis further aggravated by the fact that the stresses extending well beyond the ends of the failure. Infrom the web members are transmitted to the chord some cases, steel rods and turnbuckles, similar toin directions perpendicular and at a slope to the those recommended for tension web members, havechord. If the slope of the grain is excessive, the been used to advantage. However, it is normallychecks are likely to develop into splits by extending more desirable to replace the member and, ifto the edge of the member and may result in possible, to limit the use of steel rods and turn-failures. buckles to locations where it is impractical to shore

b. Splits often occur in the chord member atthe splices where the ends of the timbers butt.There are no sloping forces at those points toaggravate the condition, but occasionally the split 3.4.11 Heavy Timber Solid Beams and Columnscontinues well into the member, possibly passingthrough boltholes. Wherever such splits haveoccurred, it is recommended that stitch bolts beinserted through the depth of the chord member atthe splice between the bolts and the end of thechord member. In that way, the split will be keptclosed and will not have a tendency to increase.

c. Short members, such as splice plates, areespecially susceptible to checks and splits. Quiteoften, a split develops along the center of thetimber parallel to the grain; however, that conditionshould cause no concern, as splice plates are oftendeigned of two timbers of the same length, but one-half the width. If the split should develop along arow of boltholes, it is recommended that themember be replaced. The splice plates of manytrusses are designed so that they contain a row ofbolts at either edge and, at each end, one additionalbolt which is on the centerline of the member.Under such a condition and when the split occursalong the center of the splice plate, the conditionmay be corrected by inserting a stitch bolt beyondthe last bolt at each end of the splice plate.

d. At panel points when the split in the chordmember is very pronounced, even though the splitfollows a flat grain, it is advisable to install a stitchbolt within 6 to 12 inches of the outer bolt at thatconnection. A similar bolt may be inserted at theother side of the panel point. However, judgmentshould be used when installing stitch bolts at suchlocations, and they should be installed only wheresplitting is excessive.

e. If an actual failure has occurred in a chordmember, that member should be replaced. To dothis, the truss should be shored at the panel pointsalong the bottom chord and the damaged member

the truss and of the same moisture content, ifpossible.

the trusses. Steel plates should always be used incombination with shear-plate timber connectorswhen used to reinforce wood members.

Periodic inspection and maintenance schedules willnot be limited to timber-trussed structures. Manystructures of beam and column design have beenerected. As these heavier timbers season, severechecking sometimes occurs. In most cases, thischecking, although of considerable width anddepth, is parallel to the axis of the member andusually requires no attention. An attempt to closesuch checks with stitch bolts will only aggravatethe condition and cause the checks to extend com-pletely through the members. Whenever thischecking occurs in cross-grained members, correc-tive measures must be taken. In extreme cases, themembers should be replaced. In some cases, repairscan be effectively made by bolting channel or angleiron parallel to the member and connecting themwith bolts and shear plates.

3.4.11.1 Edge and End Distances and Recom-mended Spacings.

a. Bolt Connections. Figures 3-21 and 3-22indicate recommended minimum spacings and edgeand end distances for bolts in repair design. Dataare based on the use of a ¾-inch bolt. Three linesof bolts are not always satisfactory and should beused only in large members where spacing can bekept at a maximum. Shrinkage usually occurs at thecenter of the piece, and a split usually developsalong the centerline of bolts.

b. Connector Spacing Figures 3-23 and 3-24indicate recommended minimum spacing and edgeand end distances for 4-inch shear plates or splitrings for use in repair design. For connectors usedin lumber not properly seasoned, 80 percent of thetabulated allowable connector loads will apply;spacing and edge and end distances should be in-


3-33

creased above the minimum. Installation of the 4- ercised that they be properly grooved, spaced, andinch connector should be carefully and exactly per- located in order to maintain proper edge and endformed. A large number of present failures are distances. In this connection, consideration will bedirectly traceable to careless workmanship at the given to the advisability of substituting larger di-time of construction. When 4-inch connectors are mension timber for repair design.used in 1 x 6 members, extreme care should be ex-


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3.4.11.2 Allowable Loads. Stitch bolting in this case merely prevents further

a. Bolts. For repair purposes, the allowableload in pounds on one bolt loaded at both ends ina three-member connection (double shear) ofDouglas fir or southern pine (dense) is given intable 3-1.

Table 3-1. Allowable Loads for One Bolt. eter and those for nominal 2 inch lumber should be

Length of bold in main member (in)Diameter of parallel to grain

bold (in) of well-seasoned

Allowable load

lumber (lb)2½ . . . . . . . . . . . . . . . . . . . . . . . . . . ¾ 2,7103½ . . . . . . . . . . . . . . . . . . . . . . . . . . ¾ 3,2805½ . . . . . . . . . . . . . . . . . . . . . . . . . . ¾ 3,3502½ . . . . . . . . . . . . . . . . . . . . . . . . . . 1 3,6803½ . . . . . . . . . . . . . . . . . . . . . . . . . . 1 5,0005½ . . . . . . . . . . . . . . . . . . . . . . . . . . 1 5,930

When a joint consists of two members (singleshear) of equal thickness, one-half of the above member. Note the boring of a small hole im-tabulated loads for a piece twice the thickness of mediately beyond the termination of a split. Thisone of the members will apply. treatment has proved helpful in arresting continued

b. Connectors. For repair purposes, theallowable load in pounds on one connector is 3.4.12.3 Steel Banding. High strength steelprovided in table 3-2. banding such as that used to seal shipping cartons

Table 3-2. Allowable Loads for Connectors.

Type of connector with load parallelDiameter of

bold (in)

Number offaces ofmember Allowable

connectors to grain (lb)of same

boltSplit Ring 2½ . . . . . . . . ¾ 2 3,160Split Ring 4 . . . . . . . . . ¾ 1 6,020Split Ring 4 . . . . . . ¾ 2 6,140Shear Plate 2e . . . . ¾ 2 2,900Shear Plate 4 . . . . . ¾ 2 4,970Shear Plate 4 . . . . . . . . f 2 6,720

3.4.12 Timber-Repair Details

3.4.12.1 Stitch Bolts. Repair of end splits by stitchbolts is very common and normally is performedwhen a split opens up at the end greater than ¼inch. It is particularly important to control thesplitting when the end split runs through the line ofbolts. It is not advisable to completely close the endsplit with stitch bolts in the event that such closurewill throw excessive stress in the member.

deterioration of the condition. Stitch bolts to be in-stalled in heavy timber members (nominal fourinches or larger) should be d inch in diameter andlong enough to accommodate the nut and a ¼ inchcut washer at each end. Stitch bolts for use innominal 3 inch lumber should be / inch in diam-5

16

14 inch in diameter. Using larger bolts removes toomuch wood from the end of the member thusreducing the equivalent end distances. After tight-ening the existing bolts, install the stitch bolts. Seefigure 3-25.

3.4.12.2 Yoke Angles and Clamps. Figure 3-26 il-lustrates the repair of a minor split occurring at ornear the joint of a chord member. Yoke angles orclamps are preferably used in this case since stitchbolts would reduce the effective area of the chord

splitting.

has proved effective in arresting spread of splits.The bands should be of high tensile strength steel1¼ inch wide and 0.035 inch thick. The strappingshould be applied with a Signode Model PH 2stretcher which has no part remaining under thestrapping during tightening to cause slackening onremoval of the stretcher. The seals should be No.34SHOC with fastening accomplished with a modelSYC3435. See figure 3-27 for a typical steel band-ing for arresting splits.

3.4.13 Typical Minor Repairs

3.4.13.1 Minor Splits by Stitch Bolts. Figure 3-25illustrates the use of a stitch bolt in repairing scabsin which end splits have developed. Also shown isa stitch-bolted repair to wood columns in whichsplitting and deep checking along the grains haveoccurred. Except in unusual cases, it is notnecessary to stitch bolt columns unless the split isdeveloping at an angle of 1 to 14 or greater and ifthe slope of the grain tends to carry the split to theextreme edge of the column. This type of treatmentis effective in solid columns.


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3.4.13.2 Chord Splice Repairs. Figure 3-28 shows members and the chord members were badlya lower chord splice in which both the splice warped. This condition usually occurs when trusses


3-41

are constructed of light material generally 2 inchesthick with depths 8 to 10 inches or greater. Theomission of outside splice plates and an inside fillerblock between the chord was a contributing factorto the conditions shown. The remedy is to installoutside splice plates using split rings and theaddition of an inside filler block for stiffness, asshown in figure 3-28.

3.4.13.3 Split Lower Chord. Figure 3-29 illustratesthe repair of a split in a lower chord. The repair isaccomplished by adding two splice plates, one oneither side of the lower chord and the outside platecarried through the panel point nearest the fracture.The procedure in carrying this splice plate through

the nearest joint is used if there is insufficient roomon each side of the fracture to develop the fullstrength of the member when the splice is bolted inplace. Before applying the splice plates, a smallhole is drilled ahead of the split to arrest furthersplitting. Next, a clamp is applied of sufficient sizeto draw the broken member together. If a memberhas a thickness greater than 2 inches, a stitch boltis placed through the member to retain thisposition. Next, two splice scabs are applied andbolted to the fractured member using sufficientbolts on each side of the break to develop the fullstrength of the member.


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3.4.14 Repair of Complete Breaks. carry the splice plates completely through the panel

3.4.14.1 Lower Chord Using Split Ring Connec-tors. In many cases due to extreme knotty condi-tions and the use of brash (brittle) timber, it will benecessary to repair lower chords when one or moreof the members has completely failed. Figure 3-30illustrates a typical repair for a failure of this type.Note that split rings have been used, permitting theuse of fewer bolts and a shorter plate than wouldbe necessary for a bolted connection. However,experience has shown that when such a breakappears near a panel point, it is good practice to

point. The illustration also shows the installation ofnew filler blocks between the chord members. Abreak of this type cannot be adequately repaired byadding splice plates to the failed members alone,due to the difficulty in installing split grooves onthe inside face of the broken member. Therefore,the splice plate, which would normally be on theinside face of the broken member, is placed on theoutside face of the opposite chord member wheresplit rings can be readily installed.

3.4.14.2 Failed Chords. Using Bolts Without Con-


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nector Rings. Figure 3-31 illustrates an alternate necessary by this method to use a considerablymethod of repair of the same type of failure as larger number of bolts than required by the formershown. The same principles described in figure 3- method. It also is necessary to use longer pieces of

32 apply here except that, inasmuch as split ringconnectors are not used, the entire repair can beconfined to the single broken member. In order todevelop the full strength of the failed member, it is

repair timber. This method is not recommended forlarge fractures and should only be used when splitrings and the equipment necessary for theirinstallation are not available.


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3-46


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3.4.14.3 Web Members: Figure 3-32 shows a stiffener bolted to each side of the vertical with thenumber of typical breaks and defects found in the necessary filler blocks and through bolts to make aweb members of timber trusses. In the case of tight connection.member 1-2, where breaks occur in both diagonalmembers, it has been good practice to install com-plete new diagonals bolted to each side of thechords, as illustrated in the lower figure for bothtension and compression members. For compres-sion members, either verticals or diagonals, repairscan be carried out as illustrated in members 2-3 and2-4. Neither of these repairs should be used in thecase of tension members, which should only behandled by the method shown in 1-2. It isfrequently found that vertical compression webmembers, due to being overstressed, are consider-ably bowed, as illustrated by member 4-5. Thiscondition is best remedied, as illustrated in thelower figure, by the application of a new vertical

3.4.15 Repairs to a Bowstring Truss

To illustrate mass repairs to a truss, figure 3-33combines typical separate failures examined in aseries of trusses. The upper chord, as is generallythe case of a bowstring truss, is in good condition;but the web members show signs of lateral deflec-tion and the lower chord has several serious breaks.The lower chord has been repaired by installingnew chord members for the full span, using splicesas described in paragraph 3.4.13.2 above andillustrated by figure 3-28. The repair of the webmembers shown in figure 3-32 is described inparagraphs 3.4.10.3 and 3.4.10.4 above.


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3-49

3.4.16 Materials Used in Repair retard cumulative checking and splitting. Details

3.4.16.1 Hardware.

a. Slotted Washers. This type of washer canbe used as a filler in bolt tightening when the boltsrun out of takeup thread. The slotted feature makesit unnecessary in most cases to withdraw bolts frommembers. The center of gravity of the washer isbelow the bolt center so that the danger of thewasher turning and falling off the bolt is minimized.Slotted washers also can be used in backing upthin-cut washers. Many trusses were originallyconstructed using cut washers of small diameter.When bolts are tightened, they have a tendency tocup and press into the fiber of the wood. When thiscondition occurs, a slotted washer or other type ofplate washer of proper bearing surface should beplaced behind the cut washer before tightening.

b. Stitch Bolts. Frequently, it is necessary toprevent cumulative splitting of members. Stitchbolts are effective for this purpose, particularly incounteracting minor end splits in compressionmembers. The stitch bolt consists of a relativelysmall diameter bolt installed the depth of a memberwith washers at each end. As stitch bolts requirethe drilling of a hole the depth of the member, withconsequent reduction of cross-sectional area, theiruse in tension sections must be employed withcaution.

c. Yoke Angles and Clamps. Yoke angles andclamps may also be used to confine splits and

are shown in figure 3-34. Since clamps and yokeangles do not create a reduction in the net sectionof a member, their use in a tension member is sat-isfactory. It is particularly important, however, tokeep an assembly of this nature constantly tight-ened.

d. Ring Connectors and Shear Plates. Figure3-35 details the type of 4-inch split rings and 4-inchshear plates currently in use. The assembly of boththe shear plate and the split ring is indicated andrepresents assembly for new or original work. Inmany cases, it is desirable to replace wooden scabswith steel plates, necessitating the use of shearplates where split rings were originally used. As theshear plate is of smaller diameter than the split ring,some means of adapting this shear plate to thecutout for the split ring must be used. For thispurpose, a shear plate bushing has been developedpermitting a flush connection without furtherdapping of the wood member. Additional dappingis costly and may dangerously reduce the netsection of the member. This method is illustrated byA and B of figure 3-35. Split rings and shear platesare only effective when properly fitted to thetimber. This can only be accomplished successfullythrough the use of proper tools. Cutterheads andaccessories are available through regular supplysources. This procedure is not applicable to the 2½inch split ring since the comparable shear plate is2e inches.


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3-51


3-52

3.4.16.2 Timber for Repair Purposes. 3.4.18 Truss Bracing

a. Species of Wood. If inspection reveals thatscabbing and reinforcing are necessary, it is ofprime importance that mistakes made in originalconstruction are not repeated in repair. Material,design, and workmanship must be carefully consid-ered. Only wood suitable for structural purposeswill be used in the repair of timber structures. Themost common structural woods are Douglas fir,larch, southern pine.

b. Grades. Stress grades of structural woodsare specified for all repairs. Generally, acceptablegrades to specify for repair purposes are obtainedfrom the latest edition of the "National DesignSpecifications for Wood Construction" publishedby the National Forest Products Association.Record plans and original design analysis should beclosely studied to determine the original designassumptions and conditions. In the absence of thesedata, request guidance from the next highestcommand supervisory authority.

c. Painting Ends of Members. Wood driesmore rapidly at end-grain than at side-grainsurfaces. The tendency to check is, therefore, morepronounced in the end grain. A moisture-resistantend costing is recommended to protect such sur-faces from checking during air seasoning. Endcoatings will be applied as soon as possible to thefreshly cut end surface, for end checks, once start-ed, tend to go deeper into the wood as drying pro-gresses. End coatings may be divided into twoclasses: those that are liquid at ordinary tempera-tures and can be applied without being heated, andthose that are solid at ordinary temperatures andmust be applied hot. Two cold coatings beingtested at the Forest Products Laboratory, U.S. De-partment of Agriculture (Technical Note No.186)are phenolic-resin varnish, pigmented with alumi-num paste or powder, and filled hardened gloss oil.Both are tough and easily applied. Hot coating ma-terials include pitch, asphalt, resin, and paraffin.The Forest Products Laboratory maintains a list ofvendors of these materials.

3.4.17 Repair of Rafters, Purlins, and Bracing

Examine rafters, purlins, and bracing periodicallyfor damage primarily due to roof leaking. If raftersor purlins sag from overload, they are repaired bysplicing additional member or members to the ex-isting ones.

A common fault of many trusses is the lack of ade-quate bracing. Trusses require bracing to keep topand bottom chords from bowing from a straightline and to prevent them from tipping from a ver-tical plane. The primary element for truss bracing isthe roof itself; therefore, purlins and joists shouldbe securely fastened to trusses. See figure 3-36.Trusses can be stiffened by adding bracing and it ispossible to minimize other repairs through theprovision of adequate bracing. The most commontypes of bracing include the following:

3.4.18.1 Top Lateral Bracing Top diagonal brac-ing is used in the plane of the upper chords. Thepurlins act as struts. Usually two pairs of crossingdiagonals are used in each outside bay on each sideof the roof. These diagonals brace the trussestogether in pairs. The purpose of this bracing is tostiffen the structure, as the diagonals have no cal-culated stress. See figure 3-38.

3.4.18.2 Bottom Lateral Bracing Bottom lateralbracing, together with the horizontal struts or run-ners, are attached to the bottom chords of trussesand serve to tie the trusses together. Usually,bottom lateral bracing is not provided for bigtrusses unless vibration due to heavy equipment ormachinery is anticipated. See figure 3-37.

3.4.18.3 Vertical Sway Bracing. Vertical swaybracing is usually in a vertical or incline plane,along the centerline, along a sloping plane, or be-tween columns. It is used in connecting the top ofone truss to the bottom of the other. It is veryuseful during erection, and it resists wind pressureon the ends of the building. See figure 3-38.

3.4.18.4 Knee Bracing Knee bracing is often usedin large structures, and it is used in connectingcolumns to the trusses. This kind of bracing is usedmore for rigidity than strength. It is alwaysdesigned as a compression member, while all otherbracings are preferably designed as tension mem-bers. See figure 3-39.

3.4.19 Epoxy Repair of Trusses

Repair of trusses using pressure-injected epoxycompounds has been economically and successfullyapplied in recent years by comparison to conven-tional repair methods such as replacement, scab-bing, and stitch bolting. This method is particularlyuseful when disruption of work activities below therepair is of concern. The procedure consists ofthree steps: preparation, placement of injectionports, and epoxy seal injection.


3-53


3-54


3-55


3-56


3-57

3.4.19.1 Advantages and Limitations. There are cessful. More care and attention to detail are re-several advantages to using epoxy repair when quired than for nonstructural repairs.repair conditions are favorable. Properly applied,the repaired joint is actually stronger than theoriginal joint before it was damaged. However, this 3.4.20.1 Type A-1. Epoxy injection of cracked oris not true with other repair methods. The second split members at truss joints.advantage is that epoxy repair requires little shor-ing. The third advantage is that it is cheaper (asmuch as 50 percent) than conventional replacementmethods. The fourth advantage over other methodsis that the epoxy repair can reach inside of thedamaged joint. There are two major advantages inthe use of epoxy repair. First, temperature can becritical and must be considered before startingrepair. When the air temperature is high (125EF or51.7EC and above), epoxy repair should not beattempted. Second, a determination of whether theentire outside of the joint can be reached for sealingmust be made; all cracks and openings must besealed before injection or the joint will leak andmay lose its strength.3.4.19.2 Structural and Nonstructural Repair.Epoxy repair can be divided into two broad types:structural and nonstructural. Nonstructural appli-cations include waterproofing, crack sealing, andcosmetic repairs. Repairs of the nonstructural typeare usually quite simple because the goal is toprovide a seal. The work effort is successful if therepair prevents leaks. Structural repair can be dif-ficult. Often the total damage is not visible. Cracksmay be very small or as large as 1 inch or more.Sealing before injection can be difficult and, for asuccessful repair, it must be complete. Epoxy mustbe injected into all voids for the repair to be suc-

3.4.20 Types of Epoxy Repair:

3.4.20.2 Type A-2. Epoxy injection and reinforce-ment of decayed wood.3.4.20.3 Type A-3. Splicing and epoxy injection ofbroken members.3.4.20.4 Type B-1. Epoxy injection of longitudinalcracks and splits away from joints.3.4.20.5 Type B-2. Repair of bearing surfacesusing epoxy gel.3.4.21 Strength of Epoxy Repairs.

Among the many factors affecting repair are themany joint types that require repair. Figure 3-40shows a group of truss joints. As can be seen in theillustration, the number of members, lap area, grainorientation, and number of mechanical connectorswill vary. Other important factors are thickness ofmembers, age of wood, and crack width betweenlapped surfaces. Planning a repair effort shouldconsider the following:3.4.21.1 Degree of Damage. Because epoxyrepair is used to provide the shear resistance inlapped members, the degree of damage is usuallynot important. As long as there are adequate lappedsurfaces for bonding, the strength of the joint canbe completely restored. The major exception isdecay. Repairing a decayed member is difficult andrequires special expertise.


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3.4.21.2 Effect of Mechanical Connectors. All the strength of the joint is not affected by a missingjoints in wooden trusses must have some sort of connector. A glue line must fail (or deform badly)connector. In older trusses mechanical connectors before the load can be transferred to thesuch as bolts, split rings, and toothplates have been connectors. The load required to fail the glue lineused. Often it is found that some connectors have is usually greater than the connector's ability tobeen omitted or, if the joint is badly damaged, the carry the load. When the glue line fails, theconnectors may have fallen out. After epoxy repair connector will fail in most cases.


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3.4.21.3 Width of Overlap. Tests have established 3.4.23 Steps in Epoxy Repairthat the failure stress of a bonded lap joint is notaffected by the width of the overlap.

3.4.21.4 Length of Overlap. Bonded double lap-joint strength is directly related to the length of thelap in relation to the thickness of the middlemember. Thickness of the lap does not add to thestrength of the repair.

3.4.21.5 Effect of Grain Orientation. Tests indi-cate a load-capacity loss of a repaired joint as thegrain angle changes from 0E to 90E.

3.4.21.6 Effect of Glue-Line Thickness. The effectof the glue-line thickness on joint strength is sosmall that it can be discounted.

3.4.22 Characteristics of Epoxy Compounds

3.4.22.1 Chemical Grouts. Chemical groutsconsist of two or more chemicals which react toform either a gel or solid. This is in contrast tocement grouts which consist of solid particlessuspended in a liquid.

3.4.22.2 Epoxy Resins. These resins are two-com-ponent systems made of a resin base and a hardener(catalyst). Flexibilizers are sometimes added toprevent cracking of the set glue due to movementof the joint. Epoxy resins are available that cure inhigh moisture areas. They have the followingcharacteristics:

a. Ability to resist acids, alkalies, and organicchemicals.

b. Ability to cure without volatile byproducts.

c. Ability to cure without external heat.

d. Ability to accept various thickening agents.

Once hardened epoxy resins will not liquify whenheated (thermosetting) but will soften. The requiredcharacteristics of epoxy resins to be used in woodstructural repair are shown in table 3-3.

Table 3-3. Mechanical Properties for Resins Used inRepair of Wood Structures

Characteristics viscosity

Lowviscosityinjectionmaterial

High

sealing gel

Pot Life (min) . . . . . . . . . . . . . . . . . . . . . . 10-60 10-60Initial cure (hr) . . . . . . . . . . . . . . . . . . . . . 1-8 1-8Final Cure (day) . . . . . . . . . . . . . . . . . . . . 2-5 2-5Viscosity (c/s) . . . . . . . . . . . . . . . . . . . . . 200-500 NonsaggingHardness (shore D) . . . . . . . . . . . . . . . . . 80-100 80-100Modulus of Elasticity (k/in ) . . . . . . . . . .2 0.4-0.6 0.4-0.6Tensile Stress (k/in ) . . . . . . . . . . . . . . . .2 5-8 5-8Compressive Stress (k/in ) . . . . . . . . . . . .2 5-10 5-10

There are four basic steps in the epoxy repairprocedure. Each step is described in the followingparagraphs:

3.4.24 Special Member Preparations

The preparation of the repair area can range fromlittle to extensive. Individual judgment is necessaryto determine the preparations required. Thefollowing items should be considered prior to anyepoxy repair:

3.4.24.1 Shoring and Jacking. In cases where ex-cessive damage or deterioration has occurred, itmay be necessary to shore the member to preventadditional movement during repair or to jack themember back to a more normal position. Based onfield observations of damaged buildings, jackinghas been required only in isolated instances. Threereasons for considering jacking are: (1) to removeexcessive sag, (2) to relieve stresses, and (3) toclose large cracks. Jacking to relieve stresses is notrecommended. Experimental studies have shownthat it is difficult to close cracks by jacking and thatthe size of the crack is unimportant in the epoxyrepair process. Therefore, the only reason to jack atruss before repairing would be to remove exces-sive sag. Only if the sag/span ratio exceeds 1/240,should jacking be considered. If jacking is neces-sary, extreme caution should be exercised. Stressreversals could cause member failures, especially inthe vicinity of the jacking points. The differentialmovement may also damage attachments such asroofing. In general a structural analysis of thesystem should be conducted to determine the max-imum jacking force permissable. If jacking is nec-essary, gages to measure the jacking forces shouldbe utilized during the operation.

3.4.24.2 Addition of Splice Plates. Some repairsmay require the addition of splice plates, e.g., abroken member. The epoxy repair technique ismost effective for lapped joints in which the epoxyis injected between the lapped surfaces to provideshear resistance. For broken members, splices aretacked on both sides of the broken member (asshown in figure 3-41) to be later injected withepoxy. Since most failures occur at joints alreadyconsisting of lapped members, additional spliceplates are generally not necessary.

3.4.24.3 Removal of Moisture Source. For moistor decayed sections, the moisture source must beeliminated to protect the member from further de-terioration. Although most epoxy formulationsadhere in moist environments, the moisture maycause the decay to continue in encapsulated or ad-


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(B) OLD SPLICE PLATE REMOVED ANDLONGER SPLICE PLATE ADDED

Figure 3-41. PREPARTION OF MEMBERS BY ADDING SPLICE PLATES.

(A) DAMAGED TRUSS JOINT

jacent areas, and resulting in further deterioration. source of the high moisture eliminated. For trusses,If the moisture content exceeds 20 percent, the the roof should be repaired so that continuedmember should be dried out before repair and the leaking will not contaminate the repaired member.

3.4.24.4 Reinforcement. For severely decayed capacity. See figure 3-42 Epoxy injection will bondmembers, reinforcing elements may be necessary. the reinforcing members to the surrounding woodHoles are drilled and fiberglass reinforcing rods to provide increased strength. Since little ex-inserted to form either a strong connector pattern perimental evidence is available, this procedurebetween sound and unsound wood, or a stiffening should not be used without careful engineeringinternal truss or frame for increasing load carrying analysis.


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3.4.24.5 Cleaning. The area to be repaired should a puttylike consistency (referred to as a gel). Thebe thoroughly cleaned, with all dust and debris usual steps in the sealing process are as follows:cleared to provide a good bonding surface. An airjet from a compressed air source has been found tobe very effective for this purpose.

3.4.25 Joint Sealing. area; second, a means is provided for venting the

The area to be repaired must be completely sealedon the exposed surfaces except for injection andbleeding ports. The success of the repair largelydepends on the effectiveness of the sealing. Thesealant used should be a high viscosity epoxy with

3.4.25.1 Port Setting. The placing of the portsserves three purposes. First, a means is providedfor injecting epoxy into the interior of the damaged

air which is displaced by the epoxy during theinjection process; and third, a means is provided fordetermining the penetration of the epoxy into thedamaged area.


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a. Materials. One of the most common b. Placement of Ports. Ports are placed bymaterials used for ports is ¼-inch-diameter copper drilling holes with a diameter identical to thetubing. Also frequently used is small diameter (¼ to outside diameter of the port. The port is insertedd inch) standard pipe. Plastic tubing has also been into the hole and sealing gel is applied around thesuccessfully used. The primary requirements for port. The depth of the hole depends on its locationport materials are that the part should be bondable and type. Recalling that the key to a successfulwith the epoxy gel, and that it can be sealed or epoxy repair is insuring penetration into all lappedclosed during the injection itself. surfaces, the ports should be placed to maximize


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penetration. Alternative placement methods are c. Location and Number of Ports. Theshown in figure 3-43. One method is to place the minimum number of ports for single lapped surfaceport at the juncture of the lapped surfaces as is three. Two ports are usually placed at the topillustrated by port type A in figure 3-43. The hole and one at the bottom as shown in figure 3-43,is drilled at an angle to the surface while insuring however, placement may vary depending on thethat the hole includes the lap area. The depth of the shape of the lapped surfaces. For members orientedhole should be approximately ½ inch. The second at an angle-to-grain, three ports per lapped surfacemethod is to drill holes perpendicular to the lapped are usually sufficient. Hence, the total number ofsurfaces as illustrated by port type B in figure 3-43. ports would be three times the number of lappedThis method allows easier installation and allows surfaces at a joint. However, for parallel-to-grainthe penetration of multiple lap planes by drilling the members such as splices, the lap area may be longhole deeper. The hole should be drilled deep enough to justify additional ports. It is recom-enough to penetrate the lapped surfaces desired. mended that two ports per lapped surface be pro-For either method the port should only be inserted vided (one top and one bottom) for every 2-footapproximately ¼ inch into the hole. After length of spliced members. Figure 3-45 shows in-placement, the port should be sealed with gel. The stalled ports inplace for typical joints. Another lo-gel should be built up around the port as shown in cation for ports would be the cracks and splits. It isfigure 3-44. It is important to build up the gel to recommended that single ports be placed at theprevent leaking during injection and capping. extreme ends of all longitudinal splits with addi-

tional ports placed at 3-foot increments.


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3-65


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Figure 3-45. INSTALLED PORTS IN PLACE.


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3.4.25.2 Lap Joint and Crack Sealing. All cracks, significantly weaker than the injection epoxy andlap joints, bolts, holes, and defects must be com- should not be counted on for strengthening the re-pletely sealed with gel. This sealing is usually per- paired joint. Special care should be taken in sealingformed by hand using putty knives and trowels. the following since experience has shown that leaksThe gel must be thick enough to span the openings often occur at these points.and withstand pressures of 40 to 80 lb/in . A cross2

section of a crack covered with gel is shown infigure 3-46. The thickness of the gel at the crack, h,should be approximately equal to the crackthickness, t. The gel is usually spread ¼ inch oneither side of the crack. For cracks wider than dinch, a fiberglass cloth can be placed over the crackand gelled over. This procedure prevents the gelfrom penetrating too deeply into the crack andprovides a stiffening effect once the gel has hard-ened. Care should be taken to apply the gel to thesurface only. Forcing gel deeply into cracks mayobstruct the injection epoxy and could prevent theinjection epoxy from filling the voids. The gel is

a. at sharp corners.b. at openings greater than ¼ inch.c. around bolts and washers.d. around ports.

The entire joint or damaged area must be com-pletely sealed. The injection epoxy has a viscositysimilar to thin paint and will seek the path of leastresistance when injected. Any small opening willleak enough that the injection cannot continuewithout sealing the leak. Typical sealed joints areshown in figure 3-47 and typical sealed splices areshown in figure 3-48.

3.4.25.3 Leak Testing. It is recommended that painted with a thick epoxy paint. This applicationjoints be leak tested before injection. A suitable fills hairline cracks and small holes not generallyprocedure is to use compressed air. All ports visible.except one venting port and injection port shouldbe temporarily capped. Compressed air (at 25 lb/in2

pressure) is then forced into the joint. The joint isthen coated with a soap film and observed forbubbles. All leaks are marked and repaired after thefilm has dried. While leak testing may seem tedious,experience has shown that the time spent in leaktesting is more than compensated for by expeditedinjection. In addition, the joint has a higher repairedstrength when leaking is minimized.

3.4.25.4 Hairline Cracks. In some cases the dete-rioration has resulted in a number of hairline crackswhich are difficult to visually detect. Should leaktesting reveal a large number of such cracks, it isrecommended that the entire damaged area be

3.4.26 Epoxy Injection.

The next step is to pressure inject a low viscositytwo-component epoxy into the sealed joint throughthe injection ports (figure 3-49). This can usuallybe done by attaching the nozzle of the injection gunto a single port (usually the lowest) and letting theother ports serve as vents. As epoxy fills the joint,the venting ports leak epoxy and are sealed off.After all ports are sealed, epoxy injection should becontinued to insure penetration into the fibers. Careshould be taken not to inject with too muchpressure or the seal might break. A maximumbozzle pressure of 40 lb/in is recommended.2


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When possible, the entire joint should be injectedfrom a single port.

3.4.26.1 Port Capping. Various methods can beused to seal off ports during injection. One methodis to lightly tap wooden golf tees into the port.Copper tubing can be bent or squeezed closed withpliers. Wooden dowels can also be inserted. Theprimary caution is that the seals should not bebroken in the process.

3.4.26.2 Leaking During Injection. Should a leakdevelop during the injection, a quick-drying patch-ing cement can be applied. Since it is essential tofinish the injection before the epoxy initially sets, apatching cement with a 2- to 3-minute pot life isneeded. Hydraulic cements which can be mixedwith water work well. Hot-melt glues have alsobeen used successfully. Because of the porousnature of wood, leaking will occur on occasion. Noinjection should be attempted without a supply of

patching compound on hand.

3.4.26.3 Injection Equipment .Injection is usuallyaccomplished with automatic equipment, althoughhand equipment can be used. Typically, two posi-tive displacement pumps geared to the specifiedmix ratio feed the separate components into anozzle. Mixing is accomplished by forcing theepoxy through static-mixing brushes in the nozzle.As long as the flow is not interrupted for more thana few minutes, injection can progress for hourswithout damage to the nozzle.

3.4.27 Finishing

The initial cure time for many epoxies is 2 to 5hours. Final cure is usually accomplished in severaldays. After final curing, any temporary supportsmay be removed. If esthetics are important, theinjection ports are removed and sealing gel sandedsmooth so paint can be applied to finish the repair.


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(A) INITIAL JOINT FAILURE

(B) SEALED JOINT

Figure 3-47. TYPICAL SEALED JOINT.


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(A) INITIAL SPLICE FAILURE

(B) SEALED SPLICE

Figure 3-48. TYPICAL SEALED SPLICE.


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Figure 3-49. EPOXY INJECTION IN PROGRESS.


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Figure 3-50. EPOXY INJECTION PUMPING UNIT.

3.4.28 Injection Equipment c. Chain drive—geared to provide the correct

Although hand injection equipment can he used theutilization of automatic equipment isrecommended. Typical equipment is described inthe fol lowing sections.3.4.28.1 Pumping Equipment. A typical pumpingunit is shown in figure 3-50. The specific parts arenumbered and described as follows:

a. Tanks—marked for ease of identification.b. Pumps—positive displacement.

mix ratio of the two components.d. Motor—driving mechanism for pumps.e. Feedlines—transfer epoxy components to

mixing head.f. Check valves—prevents mixed epoxy from

penetrating feedline.g. Pressure gages—monitor injection flow.h. Quick disconnect couplings—attach to

mixing head.

3.4.28.2 Mixing Head. The mixing head is shown 3.4.29 Quality Controlin figure 3-51 with the specific parts numbered.The parts are described as follows:

a. Feedline inlets—feed epoxy componentsinto mixing head.

b. Mixing chamber—components mixed.c. Mixing brushes—epoxy is forced around

brushes for mixing.d. Brass petcock—on-off valve for mixed

epoxy.e. Nozzles.

(1) Insertion type.(2) Ferrule and fitting for positive

connection to port.f. Hex head sealing plug—remove for

cleaning.

One of the major difficulties associated with theepoxy repair procedure is quality control. Engi-neering inspection is one measure. However, it mayprove difficult to verify whether epoxy hascompletely penetrated the damaged area. This con-cern is often emphasized by the fact that workmenmay have relatively little experience with wood asopposed to concrete repairs. The following proce-dures are recommended for insuring a satisfactoryepoxy repair.

3.4.29.1 Epoxy Samples. In many cases laboratorytesting is not possible for wood repair in contrast toconcrete repair where test cylinders can be taken.This lack of quality control can result in seriousproblems for epoxy repaired members. Many


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(B) ASSEMBLED HEAD(A) UNASSEMBLED HEAD

epoxies are very sensitive to mix proportions. The to the specific point being repaired. Should thestandard injection equipment consists of two posi- epoxy not harden properly, the joint should betive displacement pumps driven by a single motor repaired by an alternative method.geared to obtain the proper mix. The two epoxycomponents are mixed at the nozzle, thus a fairlycontinuous flow prevents hardening of the epoxy inthe nozzle. However, crimped lines, malfunctioningpumps, or line blockages can sometimes occur. Insevere cases the problem may result in soft spotswithin joints. Frequent collecting of small samplesin containers will determine if the epoxy ishardening as expected; this should be routinelydone. It is recommended that a sample be takenbefore the injection of each joint with a notation as

3.4.29.2 Shear Block Specimens. The detection ofweak but hardened materials is much more difficult.One method is to inject shear block specimens atthe beginning of operations and after the repair ofevery fifth member. A shear specimen is cut intofour shear blocks after curing and each is tested insingle shear. The failure stress level should beapproximately equal to the ultimate strength of thewood (approximately 600 to 800 lb/in for southern2

pine). This level of shearing strength indicates ahigh-quality bond.

Figure 3-51. MIXING HEAD OF EPOXY INJECTION UNIT.

3.4.29.3 Coring. Another quality control problem devices are either time consuming, thus allowingis determining epoxy penetration into voids. Coring for only spot checks, or they destroy the sampletechniques have been developed, but none have making it difficult to detect the epoxy.proved completely satisfactorvy. The coring

SECTION V—GLUED-LAMINATED WOOD FRAMES

3.5.1 General defects, such as knots, and the kiln-drying of the

An improvement in the heavy timber constructionfield is the development of glued-laminated (Glu-Lam) members. Large members are made up fromsmaller standard dimension pieces of lumber andformed into a variety of shapes and sizes. Glued-laminated members have higher allowable unitstresses than solid timber due to the dispersion of

lumber prior to lamination. One of the most popu-lar types for buildings is the glued-laminated arch.See figure 3-52.

3.5.2 Glued-Laminated Wood Beams

Beams built up of smaller pieces can also be shapedto fit architectural and structural require-ments in


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great variety. Some of these are illustrated in figure protection from rainwater provided to the new3-52. glue-lam members by complete covers.

3.5.2.1 Deflection and Camber 3.5.3 Repair of Glued-Laminated Members

For a given span, deflection is more pronounced intimber members than in steel or concrete. Muchmore often deflection will be the governing factorin design of timber beams and girders. Designersusually have a camber placed in timber beams andgirders, based upon a full dead load and half of alive load. This means that the member will appearto arch upwards at midspan, when the roof has nosuperimposed load, and flatten out level when itsupports a moderate snow load. Under an extremesnow load, usually occurring once every genera-tion, the beam will appear to sag as far downwardas it arched upward with no snow. In observing thissituation bear in mind that either the top or thebottom of the beam could have been shaped infabrication to produce a haunch or some othernonconformity. The camber or deflection may bemeasured from a tight string line held at the sameglued surface line from one support to another.However, since members may be shaped afterglueing, the only sure way is to consult designdrawings where a camber sketch is shown.

3.5.2.2. Decay. Designers were originally lead tobelieve that glue-lam members were water resist-ant. Consequently, many structures were built withexposed beams and girders. Glue-lam arches wereanchored in exposed metal shoes which filled withrain water. These areas are decaying badly andneed to be repaired by replacement including full

Glued-laminated members, having been kiln-driedbefore gluing and being of smaller selected pieces,do not ordinarily have the same defects as solidwood members. In arches, periodic inspectionsshould be made to detect any delamination or sep-arating of one piece in the member from another.Minute cracks should be carefully examined; and,if larger than / inch, they should be examined by1

16a competent structural engineer. Arches should beexamined for alignment and settling.

3.5.4 Corrective Measures

3.5.4.1 Arches. Adjustment of tie rods should bemade only as directed by a competent structuralengineer. Bolts and fasteners at the peak jointshould be tightened; however, since the materialhas been dried, this should not be required as fre-quently as connections in solid timbers. At the di-rection of an engineer, steel plates, stitch bolts andspikes may be used to repair arches that have sep-arated or delaminated.

3.5.4.2 Beams. Beams may be required in the sameway, and lines for detecting sag or deflectionshould be used.

3.5.4.3 Purlins and Joists. Purlins or joists areusually fastened to these members with hangers.Shimming of the purlins in the hangers can be ac-complished with small wood wedges or shims.


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4-1

CHAPTER 4

EXTERIOR WALLS

SECTION I—CLASSIFICATION OF WALLS

4.1.1 Structural Types several general categories. See Tri-ServicesExterior walls may be classified as load-bearingwalls (walls that support loads from floors, roofand equipment plus their own weight), nonload-bearing walls (walls that support only their ownweight), and curtain walls (walls that have theirown weight supported on structural members).4.1.2 Material ClassificationsExterior walls fall into four general material clas-sifications, with a wide variety of materials andapplications:4.1.2.1 Wood and Wood Products: Wood shingles,weatherboard siding, plywood, prefabricatedpanels.4.1.2.2 Concrete and Masonry: Brick, concretemasonry units, reinforced concrete, precastconcrete panels, structural clay tile, stone, exteriorplaster (stucco).4.1.2.3 Metal: Corrugated iron and steel, alumi-num sheeting, precut sheet metal, enamel-coated,prefabricated steel panels, protected metals, pre-fabricated panels.4.1.2.4 Mineral and Chemical Products. Asbestosshingles, asbestos-cement sheets (flat and corrugat-ed), prefabricated panels (flat and corrugated),glass block and vinyl.4.1.3 Finishes and Protective CoatingsAs distinguished from exterior wall surfaces them-selves, protective and decorative coatings fall into

Manual, "Paints and Protective Coatings," for in-formation regarding their application and mainte-nance. Exterior plaster (commonly referred to asstucco) is the application of a portland cementplaster to the exterior wall surface. Chapter 5 ofthis manual discusses the materials and applicationof interior portland cement plaster in detail.Exterior plasterwork is similar to interior plaster-work except that the exterior plaster finish coatnormally contains a waterproofing agent.

4.1.4 Maintenance and Repair

Regardless of the material used in the constructionand finish of exterior surfacing, it is necessary thatmaintenance measures appropriate to the situationbe planned and carried out on a regular schedule.Where repair is made to existing types ofconstruction and material, it is best to match the as-built specifications as nearly as possible. Improvedconstruction techniques and materials should beconstantly examined to prevent or offset similarfailure. Where weathering, normal wear or otherreasons dictate a requirement for repair, re-placement or refinishing of an exterior wall, con-sideration must be given to either matching (or du-plicating) existing material, replacement of theentire covering, or a completely new finish over theexisting surface.

SECTION II—WOOD EXTERIORS

4.2.1 Causes of Failure

4.2.1.1 Moisture. The most common failure ofwood and wood-products exterior siding is causedby moisture. Prolonged weathering, leaks, andcracks, which allow moisture to enter and collectbehind exterior coverings, are a source of eventualproblems. Condensation within and behind wallsalso contribute to the problems of maintenance,repair, and rehabilitation. Figure 4-1 demonstratesthe mechanics which may produce damagingmoisture behind paint and within walls and

illustrates the use of a vapor barrier to avoid theseconditions.

4.2.1.2 Inferior Workmanship and Material.Inferior materials used in initial construction mayallow early warping and cracking, or in instances ofgreen lumber, bleeding of sap. Painting on wetmaterial may cause early scaling, which in turnexposes areas of the wood to severe weathering.Insufficient, loose, and displaced nailing willeventually cause problems.


4-2

4.2.1.3 Structural Failures. Settlement of founda- important to determine the cause of failure andtions, which in turn causes displacement and mis- correct it before surface repairs are made.alignment of framing members, may crack, misalignand damage facing material. Occasionally, aframing member may fail under loading conditionswhich exceed those for which it was designed orbecause of inferior material. This in turn can causedisplacement and damage to siding. A fact that isfrequently overlooked in maintaining wood siding 4.2.2.3 Patching, Renailing and Resurfacing.is that nailing or adhesion methods of fastening Make a careful check to determine that existingsheathing on the framing (studs or furring strips) structural, functional and material conditions war-provide strength to the basic structure, as well as rant repair to the existing wall rather than completeform a covering. It follows that broken or loose residing, insulation, or other overall repair orsiding detracts not only from weatherproofing rehabilitation. Where existing situations arefunctions and appearance, but also from the satisfactory, replace damaged material with likestrength of the structures as well. material. Cut out sufficient areas beyond the dam-


4.2.2.1 Inspections. Regularly scheduled inspec-tion will determine the need for timely maintenanceprocedures. Neglect of maintenance and repairmeasures leads to greater and more costlyproblems. Painting and surface treatment must bekept in good repair. Specific structural repair andimprovement methods are presented below. It is

4.2.2.2 Causes of Damage. Siding material may bedamaged by normal weathering; severe wind, snow,and ice; falling tree branches; fires; vehiclecollisions; spillage of grease, fuels, and chemicals;and vandalism.

aged part to obtain good jointing and sound nailing.Tighten nails in existing material to be left in place.Be sure that material receiving the new nailedpieces of sections are sound and true. (See chapter3 for framing repair.) Cover replacement woodwith finishes or paint matching the original design.When "as-built" plans are available, it is well toexamine the original construction detail forassurance that out-of-vision construction and utili-ties will not be damaged.


4-3

4.2.2.4 Repair of Wood Shingles. Warped, split, or and faulty caulking. It is usually more economicalcurled shingles should be removed with a ripper and satisfactory to replace damaged or deterioratedand replaced in a similar manner to roofing shin- panels rather than to attempt patching.gles. See Tri-Services Manual, "Roof Maintenance"(TM 5-617, AFM 91-31, NAVFAC MO-113, andMCO P11014.9)

4.2.2.5 Repair of Prefabricated Panels. Panelsiding will be periodically checked for looseness

4.2.3 Residing

When existing siding does not meet functional re-quirements, careful consideration will be given toresiding over the existing material. At this time it is


4-4

well to consider factors in connection with insu- residing, the new siding may butt against or overlaylating qualities of the material to be used. If the the opening trim. If it overlays the trim, it should bewalls are already suitably insulated within, siding or finished by an abutting metal or wood staffshingles may suffice. If new or additional insulating moulding. If it butts against the opening trim,qualities are required, careful consideration should adequate and appropriate flashing or caulking mustbe given to the insulating factors of the new be used.material. These considerations include whetherpresent walls are vented or depend on porosity sovapor may reach the outer air, and what effect theaddition of material may have on the existence ornonexistence of a vapor barrier within the wall, andthe effectiveness of the present airspace in the wallstructure. When a qualified engineer has de-termined what type of material is to be used, thefollowing general rules apply for placing insulating 4.2.3.8 Underlay. On residing work where theor wood sidings. sheathing or old wall surface is not in sound condi-

4.2.3.1 General. The old wall to be recovered willbe repaired to provide a sound, substantiallysmooth, true surface having adequate nail-holdingcapacity and the ability to hold the new sidingfirmly.

4.2.3.2 Over Unusual Construction. Where struc- hold the underlay in place until covered with siding.tures have thin level siding or similar materialsapplied directly to studding, which sometimes maybe widely spaced, it is appropriate to fasten to theexisting wall properly sized wood strips, placed atthe nailing location for the new siding. These stripswill serve as adequate nailing bases provided theyare shimmed to true line and are properly secured.

4.2.3.3 Over Other Material. Where it is deter-mined that wood siding should be on a buildingwhich has an existing surface, such as asbestos-cement or metal, which will not act as a nailingbase, it is necessary to use wood nailing stripswhich are secured through the existing siding andinto the wall studs. Otherwise, all old siding and theold sheathing may have to be removed down to theexisting studding and then replaced with newsheathing as well as siding.

4.2.3.4 Residing Over Stucco. New siding will notbe applied over old stucco. Remove the old stucco,nails, and lath, and apply new siding on existingwalls.

4.2.3.5 Other Considerations. Whenever siding isreplaced or added to existing siding, proper consid-eration must be given to placement of asphalt-saturated felt underlays, flashing at windows anddoors, termite protection, proper surface treat-ments, and other items pertinent to good construc-tion practices. These considerations will be de-pendent upon the existing conditions.

4.2.3.6 Moulding, Flashing, and Caulking When

4.2.3.7 Gutters and Downspouts. New or rehabili-tation work involving the repair or replacement ofgutters and downspouts will be phased to insurecontinual drainage of roof runoff. This will preventstorm water damage to the new work or to the newsiding prior to surface treatment, and will preventwater from entering uncovered wall areas.

tion, an underlay of sheathing paper must be ap-plied to prevent the infiltration of wind and mois-ture. Apply the underlay as the application of thesiding progresses, applying only the amount of ma-terial which can be covered by the end of each day'swork. Use only enough small nails or staples to

4.2.4 Vapor Barriers

A vapor barrier is the best means of preventingcondensation by keeping the vapor from reachinga cold surface. When existing buildings have notbeen provided with a vapor barrier and condensa-tion problems exist, some relief may be obtained byuse of vapor-resistant paint on interior wall faces.However, application of a vapor barrier on theinside of the warm side of the exterior wall ispreferable. There are a variety of vapor barriermaterials, such as impregnated paper, plastics, andmetallic sheets. In most instances where a vaporbarrier is to be applied within a wall, it is best touse an insulation board, batts, or similar materialwith an integral factory-applied vapor barrier. Thisaccomplishes the purpose and incorporatesinsulation at the same time.

4.2.5 Ventilation

Venting of walls, attic, and crawl space to allowescape of vapor to the outside air will help over-come the problem of condensation. Walls may beventilated by vents which are designed to preventthe entrance of rain or snow and are screenedagainst insects. Vents with screens may also beplaced in attic space and crawl space. Vents may beplaced in loft spaces, below flat roof decks, in gablewalls (louvered), in roofs (by installing insectscreens at the eaves), and wall vents in crawlspaces. See figure 4-2.


4-5

4.2.6 Insulation conditioning) is of primary importance. A study of

Exterior wall insulation has proved its worth manytimes. In maintenance of structures, questionsconcerning the sufficiency or deficiency of in-sulating qualities of walls (as well as ceilings androofs) often arise. Some of the considerations re-garding its use are discussed below.

4.2.6.1 General. The use of insulation varies tomeet climatic conditions of the area in which abuilding is located, the use of the building, and thestructural features of the building itself. The eco-nomic feature of saving and equalizing heat (or air-

the combined conditions cited above will determinethe best type and method of application ofinsulation for a specified use. Fireproofing qualitiesand condensation control must be considered, aswell as the insulating value of the product to beused. For consideration of double-glazing (stormsash) and weather stripping in conjunction withinsulating, see chapter 7 of this manual.

4.2.6.2 Types and Uses of insulation. Increased in-sulation reduces annual energy costs and increasesinitial installation costs and annual maintenancecosts. The greater amounts of insulation produce


4-6

unusual installation problems and increase the initial manufacturer's instructions for proper thickness,costs disproportionately to the energy saving. The form and fastening. Figure 4-3 illustratesoptimum amount of insulation can only be application of insulating batts, blankets, and utilitydetermined by complete analysis of costs and sav- batts to standard wood-constructed walls. Figureings. See appendix C, paragraph C.2.2.3. 4-4 shows methods of placing insulated material onAccording to the DOD Construction Criteria masonry and metal sidewalls.Manual (see appendix A), buildings to be heated to70EF 21EC) must have a factor in walls of 0.1either in new construction or in repair renovationwork.

a. Roll blankets may be used where access to Start at top of stud space and work down if rollthe space between studs permits their use and blankets are used. Batts can be installed from floorfastening. Space must be thoroughly accessible and up. Staple or nail flanges to stud at 5- to 6-inchfree of obstacles. spacing. Make sure vapor barrier faces building

b. Batt blankets may be used in areas similarto those for rolled material.

c. Loose material (pellets or wool) is best care on the cold side of pipes and drains. Compresssuited for areas where access is through a small insulation behind pipes where possible or pack withspace. Intrawall areas between the studs and attic utility batts or pouring wool or scraps from batts orspaces may be poured with loose insulation blankets. Cut and apply vapor barrier to providematerial. It may also be forced in under pressure by vapor protection.compressed air. This form of insulation isparticularly adaptable to small areas aroundwindows and doors and in wall utility compartmentvents.

d. Other types of insulation include rigid andsemi-rigid composition board, which includes stiff-ening material, such as fiber, to make a materialself-supporting. It is used most generally for pe-rimeter insulation, such as around concrete slabs oras sheathing under the siding. Utility batts areformed from insulation, but with no envelope orvapor barrier to break the flow of air through thematerial. It may be used when no vapor barrier isrequired or where a separate vapor barrier has beenprovided.

4.2.6.3 Placing Insulation. It is most satisfactoryto place roll or batt insulation between the studs ofa wall while either the inside or outside surface ofa building is uncovered. Thus, when resheathing theouter surface of a wall or replacing the innersurface, consideration should be given to installinginsulation. When both wall faces are covered, it isnecessary to pour loose insulation from the top orforce it in by compressed air from some opening inthe wall. In any case, care should be exercised tofill all small crevices and to pack material intoconfined spaces, particularly around piping andwiring. The vapor barrier side of insulation shouldface toward the warm side of the wall. In placingany type or kind of insulation, follow the

a. Batts and Blankets. In figure 4-3, thefollowing steps are demonstrated for batts andblankets: Cut insulation to stud height plus 3inches for top and bottom, nailing flange exposed.

interior. Press insulation closely together at joint sothat no voids are left. Make sure vapor barrier isnot broken by spaces at joints. Insulate with special

b. Utility Batts. In figure 4-3 the followingsteps are described for utility batts: Stack 15 by 10inch utility bats between studs. If the 15 inchdimension is placed horizontally, batts fit betweenstuds spaced 16 inches on center. With the 15 inchdimension vertical, two batts can be packed intothe space between studs on 20 inch center. Tackvapor barrier paper over the insulation to preventcondensation. For complete vapor protection, thevapor barrier must be continuous at joints. Applyroll or batt blankets to furring strips following di-rections given for wood sidewalls.

c. Metal Buildings. See figure 4-4. Attach fur-ring strips to purlins or girts of the metal buildingon a standard spacing to tack roll blanket insula-tion. Staple or nail roll blankets to furring strips.Make sure vapor barrier is continuous to preventcondensation on steel sheets. Cover with desiredfinish.

4.2.7 Exterior Steps

Wooden exterior steps are subject to considerableweathering and mechanical abuse. Wood columnsand posts supporting exterior steps and platformsshould be set in concrete with wood parts no closerthan 4 inches to the ground. Ease of access to thesestructures will make inspection simple and repairuncomplicated.


4-7


4-8

4.2.7.1 Treating Porch and Walkway. Flooring 5 inches of uncut lumber along and parallel to theTreated lumber should be used if available. How- bottom edges of the stringers. Maintain uniformever, if it is not available, immediately upon deliv- tread widths and riser heights throughout the run.ery at the building site, treat all matched or square- Treads are formed of 2 x 4's or 2 x 6's or a combi-edged flooring and planking to be used on the nation of the two sizes spaced ¼ to ½ inch apart.exterior with a preservative sealer before it is Risers are left open. Set lower ends of the stringerexposed to the weather. Immerse boards fully for on concrete footings at least 4 inches above thenot less than 15 minutes in a slow-drying wood ground.sealer. After treatment, carefully stack lumber andprotect it until ready to use. Before installation, dipor brush-coat all cut ends of flooring with sealer;after installation, apply a brush coat of sealer to anysurfaces which have been abraded, planed, scraped,or sanded. Square-edged material laid with openjoints should be used for open walkways in a. Replacement in kind using salvageablehospitals and other installations where open joints material supplemented with new material.are not objectionable.

4.2.7.2 Repairs. Normally, the component mem- pipe railings.bers may be repaired by replacing the damagedparts in kind. Use sound material, 2 or 3 inchesthick, for stringers, and space them more than 24inches on centers. Cut stringers to form treads,using planks of sufficient width to provide at least

4.2.7.3 Replacements. Expected utilization of thebuilding and extent of damage are the determin-ing factors as to which of the following methodsmay be the more economical for complete replace-ment:

b. Concrete steps and platforms with metal

4.2.8 Porches

The same maintenance generally applies to porchflooring and supporting members as for framing.Treatment of material and procedures are as dis-


4-9

cussed in paragraph 4.2.7.1 above. Care will be replaced or reinforced to match the existing struc-taken to maintain porch flooring and rails in good ture.condition.

4.2.9 Loading Platforms

Particular attention must be given to inspection andmaintenance of loading platforms due to theconsideration of constant application of changinglive loads to the floor surface. Movement of largequantities for heavy materials, the impact of fallingloads, and the constant hazard of vehicles collidingwith the platform framing call for frequentinspection and maintenance. Framing is generally

4.2.10 Canopies

Repair of existing canopies or construction of newcanopies will be restricted to areas and conditionsas prescribed by the installation engineer. Repairsare usually made by replacing the damaged part orparts in kind. New canopies, when permitted, willbe of the most economical construction consistentwith the expected utilization of the buildingconcerned.

SECTION III—CONCRETE AND MASONRY

4.3.1 General. Remove all dust and loose material with brushes,

The frequency of maintenance for masonry andconcrete exterior walls is less than that for mostother exterior materials. Leakage through concretewalls is caused by cracks in the concrete and, inrare cases, porosity of the concrete. Most defectsthat cause appreciable problems, such as leakage,are due to the expansion and contraction of thestructural members. Other common causes are set-tlement, excessive floor loadings, and poor work-manship in the original construction.

4.3.2 Mortar

4.3.2.1 General. Mortar made from good-qualitymaterial, mixed and placed under proper weatherconditions and in a workmanlike manner helpsproduce weather-resistant, durable masonry.

4.3.2.2 Defects and Damage. Weathering maycause a spalling of mortar joints under the bestconditions. Poor mortar mixes are usually at fault.when the face of the masonry walls is marred bystains and efflorescence. Impure water containingacids or organic matter and improper sand in themortar mix not only cause stains through bleeding(spillage of water over a masonry surface duringconstruction or curing), but also accelerate weath-ering of the mortar joints.

4.3.3 Repointing

Repointing with the best materials and skill work-manship will correct the most common fault, de-fective mortar joints.

4.3.3.1 Removing Old Mortar. Since removingmortar by hand with hammer and chisel is difficultand expensive, most masons who specialize inrepointing use portable electric-driven grindingwheels to simplify the job. Cut out cracked or openmortar joints to a depth of at least ½ to ¾ inch.

compressed air, or water jet. If water is used, nofurther wetting of the joints may be needed unlessthe work is delayed.

4.3.3.2 Recommended Mix. Use mortar of aboutthe same density as the original mortar, or use aprehydrated mortar mix in the following propor-tions by volume: 1 part of portland cement, 1 partof lime putty or hydrated lime, and 6 parts of sand.Prehydrate the mortar by mixing it about 2 hoursbefore use, adding only about half the mixingwater, to eliminate excessive original shrinkage andvolume change.

4.3.3.3 Application. At the end of the 2-hourcuring period, work the mortar, adding enough ad-ditional mortar to make the mixture plastic, but notenough to make it run. Be sure the joints are damp,and then apply the mortar by packing it tightly intothe joints in thin layers. Tool the joints to smooth,compact, concave surfaces. If openings in themortar are small, cutting out the joints isunnecessary, and following procedure may be used.Mix grout in proportions by volume: ½ sand, dportland cement, c limestone flour, powdered flint,or fine hydrated lime. Wet the joints, and apply twocoats of grout, brushing it vigorously into thejoints.

4.3.3.4 Protection. Protect all fresh repointingfrom direct exposure to hot sun and drying windsuntil it has set hard.

4.3.4 Efflorescence

4.3.4.1 General.. The source of efflorescence ofwalls can be found if close inspection is made whenit first appears. The immediate remedy to preventrecurrence of efflorescence is to check causes ofexcessive moisture that contacts the wall, such asdefective flashings, gutters, downspouts, copings,and mortar joints. If it appears at the edges of the


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masonry unit, the mortar probably is at fault. a. Age of Structure. Determine the age ofEfflorescence at the center of the unit indicates that structure at the time the efflorescence appeared. Ifthe masonry unit and mortar may be responsible. the structure is less than 1 year old, the source of

4.3.4.2 Cause of Efflorescence. Efflorescence onmasonry usually appears as a light powder or crys-tallization and always indicates trouble. Aside fromits unsightly appearance, it is evidence that enoughmoisture may be penetrating the wall to causedisintegration of the masonry. The two conditionswhich generally produce efflorescence are thepresence of water-soluble salts (in masonry units,mortar, or both) and moisture which deposits saltson the wall surface when water evaporates. This b. The Location of the Efflorescence. Thelatter may be excess moisture caused by extra location both on the structure and on the masonrysoaking of units before laying, or moisture taken up unit or mortar joint should be carefully noted. Theduring storms after erection of the wall. location of the salt crystals on the joints or the

4.3.4.3 Water-Soluble Salts. Soluble salts may bepresent in brick, hollow tile, concrete blocks, ormortar. Tests have shown that only a small per-centage (probably not more than 10 percent) ofwell-burned clay and sand-lime brick and hollowclay tile contributes to efflorescence. Secondhand c. The Condition of the Masonry. Carefulbrick, because of its uncertain origin and previous examination of the profile of the mortar joints, thecontact with mortar and plaster of unknown com- condition of the mortars, the type of workmanship,position, may cause efflorescence. Concrete blocks the condition of caulked joints, the condition ofare often made of materials containing efflorescing flashing and drips, and deterioration or eroding ofsalts. Portland cements, limes, and sands used in mortar joints in coping or in sills should offer cluesmortars often contain soluble salts that cause ef- as to the entry paths of moisture into theflorescence. The Wick Test for efflorescence, as construction.described in ASTM C-67, is recommended fordetermining the presence of soluble salts inmasonry units and mortar ingredients.

4.3.4.4 Excessive Moisture. Since moisture is nec- tion on the walls, leaking pipes, faulty drains, andessary to carry soluble salts to exterior masonry condensation on heating and plumbing lines. Itsurfaces, efflorescence is evidence that construction should be emphasized that these are rare and un-faults have permitted moisture to enter the wall. usual sources of moisture for efflorescence. TheExcessive moisture in walls may be caused by principal sources of moisture should be thoroughlydefective flashings, gutters, downspouts, copings, examined before these secondary sources are con-or improperly filled mortar joints. Location of sidered.efflorescence does not always mean that water isentering the wall at that point. Streaks on the wallfrom the top down or patches some distance fromthe top might indicate defective gutters or copings.Patches of efflorescence are sometimes caused byopened mortar joints or projecting brick courseswithout enough wash (upper surface of the brickwhich is sloped to shed water). Water may alsoenter openings at windowsills and around windowand door frames. Efflorescence close to the groundmay indicate ground water drawn up by capillaryaction.

4.3.4.5 Efflorescence Analysis. The followingchecklist is helpful in determining causes of efflo-rescence:

the salts is probably the cement in the mortar, andthe source of the water is usually constructionwater. However, if the structure is more than 2years old, construction details should be examinedfor possible leaks in the wall or the adjacent con-struction. The sudden appearance of efflorescenceon an established building previously free of efflo-rescence is normally attributed to a new entry ofwater into the construction assembly.

masonry units may help in determining the sourceof the salts. The recent use or occupancy of thebuilding should also be noted. Has the buildingbeen vacant for some time? Has it been altered,expanded or modified?

d. Other Source of Water. If the usual sourcesof moisture have been eliminated, considerationshould be given to other sources, such as condensa-

4.3.5 Types of Cracks

4.3.5.1 Horizontal Movement. Cracks in this cate-gory are usually long cracks in the mortar joints.They generally occur along the line of the floor orroof slab or along the line of the lintels over win-dows and doors, resulting from horizontal move-ment of the slabs involved. Where these cracks turna corner they frequently rack down (or up) asshown in figure 4-5. Racked-down corners are dis-cussed in paragraph 4.3.8.4 below.

4.3.5.2 Settlement. This usually results in diagonalcracks that reach from the lintel of one window ordoor to the sill of an adjacent window. Thesecracks generally follow the mortar joint with an


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occasional break through the masonry units. and are the result of excessive deflection, or some-

4.3.5.3 Deflection. Vertical and diagonalmovement cracks usually occur in lintels and beams

times shrinkage. See figure 4-6.

4.3.5.4 Shrinkage. Haphazard cracks in mortar as support through deterioration; failure attributed towell as in concrete, resembling a road map, are the uncalculated secondary stresses such as creep,result of shrinkage. These cracks seldom amount to vibration or impact; or progressive minor failuresmore than hairline cracks, and seldom are a cause resulting in a major failure.for concern.

4.3.5.5 Miscellaneous. Various combinations ofthe cracking discussed may occur or may be com-bined singly or collectively with other failures, suchas excessive short-term loading from the elements;external damage from vehicles or objects; failure of

4.3.6 Repair of Cracks

4.3.6.1 General. Before any attempt to repair acrack is made, an engineering investigation shall bemade to determine the cause of the crack. Thecause should be corrected first. Repairs to cracks


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in masonry have often resulted in an unsightly to the repair described for cracks in joints, usingappearance. Cases exist where fine hairline cracks any procedure determined feasible and economical.were chiseled out and repointed with mortar whensuch work was entirely unnecessary. In exposedwalls, it is extremely difficult, if not impossible, tochisel out a joint and repoint it without producinga repaired area noticeably different from the sur-rounding masonry. The repaired joint in such workwill be noticeable from an appreciable distance,whereas the hairline crack is barely visible. A fewinstances exist where the pointing mortar was leftrecessed below the surface of the block, thusactually defining and calling attention to the crack.Another erroneous practice in repair is to fill thecrack with plastic caulking compound or abituminous material having a color dissimilar tothat of the masonry surface, resulting in an objec-tionable appearance. In considering the repair ofcracks in concrete masonry walls, the followingprecautions should be observed.

a. Do not attempt to repair cracks as soon asthey appear. Observe the crack periodically over aperiod of time to determine whether further crack-ing or widening of the crack will occur. Determinethe cause of the crack and correct. No attemptshould be made to repair cracks in a new wall,unless such action is absolutely necessary toprevent the entry of water, or for similar reasons.

b. Do not attempt to repair a fine crack bychiseling out a deep grove and repointing. Repairfine cracks by filling or bridging over with acement-based wash or paint.

c. Do not caulk cracks above grade with lightplastic or dark bituminous caulking compoundswhich will contrast with the wall finish. If suchmaterials must be used, seal the caulking by coatingwith shellac or aluminum paint and then paint tomatch the surrounding area.

d. In filling joints with cement-sand mortar,size the sand to the width of the crack. Be sure tomoisten the old concrete or mortar surrounding thecrack to develop good bond and cure the newmortar by keeping it damp for 2 or 3 days. Do notapply waterproofing above or below grade until thepointed wall has dried (set).

e. Seal cracks below grade to preventmoisture from entering or passing through the wall.

4.3.6.2 Determination of Method of Repair. If thecracked masonry units to be repaired are in a wallof some prominence, where patching would be aneyesore, the cracked masonry units shall beremoved and replaced. If the final appearance ofthe wall is of little consequence, the crackedmasonry units may be patched in a manner similar

4.3.7 Concrete Repairs

4.3.7.1 Routing and Sealing. Repair large cracksby first cutting them out to a depth of about 1 inchand a width of inch. Remove all dust and loosematerial with brushes or compressed air. If thecracks have been caused by initial shrinkage orexpansion of the structure, fill them with mortar. Ifthey are caused by an accepted recurrent movementof the structure, fill them with caulking material.Before applying mortar, wet the crack andadjoining surfaces thoroughly. Then neatly apply aslurry of portland cement and sand. Use 1- to 3-mixcement-sand mortar. To reduce shrinkage,prehydrate the mortar by mixing it about 2 hoursbefore using it, adding only about half of the mixingwater. At the end of the 2-hour curing period,rework the mortar and add enough water to makethe mortar plastic, but not enough to make it run.Pack the mortar in the crack in fairly thinsuccessive layers and tool it to a smooth surface,slightly in front of the adjoining surfaces. Shrinkagewill be further reduced by keeping the patchedportions damp for 48 hours. Caulking materialshould conform to Federal Specification TT-C-598.Use Grade 1 for gun application and Grade 2 forknife application. Grade 2 will shrink less thanGrade 1. Before applying the caulking material,swab the cracks with a cloth moistened withturpentine or mineral spirits. Do not use thinners inthe caulking material Do not apply primers. Theyusually stain the concrete and seal the pores,preventing a good bond. To place caulking com-pounds in cracks or expansion joints that havepreviously been filled with caulking, first removethe old caulking to a depth of ¾ inch.

4.3.7.2 Repairs Using Epoxies. The use of epoxiesfor bonding broken surfaces is the most successfulmethod for sealing cracks in concrete.

a. Cracks as narrow as 0.003 inch can besealed with epoxy compounds. Wide cracks inhorizontal surfaces may often be sealed by pouringthe epoxy compound into them; but in verticalsurfaces and in the narrowest cracks in horizontalsurfaces, applying the sealant by pressure isnecessary. The usual practice is to drill holesapproximately ¾ inch deep and ¾ inch in diameterinto the crack from the face of the concrete at 6- to12-inch centers and inject a solvent to flush out thedefect. Valve stems or other types of entry portsare fastened in these holes with an epoxycompound. The smaller the cracks, the closer thevalve stems should be placed. The surface crack


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between the valve stems is sealed with a high The annular grout sleeve is designed to burst underviscosity epoxy or other compound that will pressure which permits grout to flow into thecontain the pressure of the injection process. formation.

b. The injection process begins by pumping a c. A slotted or perforated pipe may be drivenlow viscosity epoxy compound into the valve at the into a formation and then grouted, or an open-endlowest elevation until the epoxy level reaches the pipe may be driven to a desired elevation and thenadjacent valve. All valves in the circuit are then grout. The open-end pipe can be kept open bycapped. The highest pressure used safely without plugging the open end with a rivet or bolt duringcausing relative movement between parts of the driving. When the desired elevation is reached thestructure is applied to force the epoxy compound pipe is raised several inches to allow the rivet orinto hairline cracks. The pressure should approach bolt to work free from the open end when pressure100 lb/in if possible and should be maintained from is applied by grouting. The pipe may also be un-2

1 to 10 minutes or more. The pressure is then plugged by placing a smaller rod inside the injectionreleased, and more epoxy compound is pumped pipe to total hole depth and slightly beyond.through the same valve until the succeeding valveis capped; the process is repeated with successivevalves until the crack has been completely filled,pressurized, and all valves capped. If larger quan-tities of grout than anticipated are required, furtherinvestigation is necessary. Cores are often takenlater to check penetration and strength.

4.3.7.3 Chemical Grouting. Chemical grouts con-sist of solutions of two or more chemicals that resetto form a gel or a solid precipitate, as opposed tocement or clay grouts that consist of suspensions ofsolid particles in a fluid. Cracks as narrow as 0.002inch have been sealed in concrete with chemicalgrout. The advantages of chemical grout includeapplicability to a moisture environment, wide limitsof control of gel time, and application on very finefractures. Disadvantages are high cost, high degreeof skill and expertise for satisfactory use, and shelf- 4.3.7.4 Small Cracks in Concrete. Repair smalllife considerations and safety precautions required cracks by thoroughly wetting and then brushingfor successful use. cement-sand grout into them. Mix grout in propor-

a. The ultimate goal of grouting is to place acertain grout at some predetermined location.Down-hole grout placement can be accomplishedby several means. The simplest grouting situation isto pump or pour the grout directly on a surface orinto an open hole or fracture. The simplest down-hole method using pressure for placement would bethe use of one packer to prevent the grout fromcoming back up the hole while it is being pumped. 4.3.7.5 Large Broken Areas. Repair large broken

b. Selective down-hole grouting for anappreciable hole can be accomplished by placingtwo packers, one above and one below the area tobe treated, and then injecting the grout. Anotherselective grout placement method is by use of"tubes a manchettes." This method entails using atube with a smooth interior that is perforated atintervals and sealed into the grout hole. Theperforations are covered by rubbersleeves,"manchettes," which act as one-way valves.Selective grout placement is obtained by a double 4.3.7.6 Precast Concrete Walls. Most precastpacker arrangement that straddles the perforations. slabs and panels are of dense, high-strength

d. Using the two-solution process, drive aperforated pipe a certain distance and inject thegrout solution. This process is continued until totaldepth is reached and then grout solutions of theremaining chemicals are injected to complete thereaction as the pipe is extracted.

e. Selective placement of grout can be accom-plished without the use of packers. This involvesgrouting a pipe in place, lowering a gun perforationunit that contains either shaped, chargedprojectiles, or a special jet charge, and firing theprojectiles or jets to penetrate the pipe somedistance into the formation. Either of thesemethods gives access to previously groutedformations and virgin formations. Elevation anddirection can be dictated by this operation.

tions, by volume or equal parts of portland cementand dry sand, passing a No.50 sieve. Liquid shall beadded to produce a mix suitable for brushing.Cement and sand shall be selected to produce ashade of grout that matches existing concrete.Brush the grout vigorously into the cracks. Afterthe cracks have been filled, keep them damp forabout 36 hours.

concrete areas by cutting out enough loose con-crete to expose the metal reinforcement. Removeall dust and loose materials. Wet the existing sur-faces thoroughly and then cost them with a neatcement-sand slurry, as recommended for largecracks. Then apply the new concrete of a mix cor-responding to that of the existing concrete. Mixingand application should conform to the applicablerequirements. After the concrete is applied, keep itdamp for 48 hours.


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concrete. Webs are usually thin. Repair large cracks grout into the hole, if required. Allow grout to setin monolithic concrete. Do not attempt to cut for time period specified by manufacturer beforechannels in precast slabs or panels. Repair small applying load. Use a heavy liquid grout forcracks as indicated in paragraph 4.3.7.2. horizontal surfaces and a gel consistency grout for

4.3.7.7 Concrete Spalling. Repair concretespalling using a 2-part polymeric mortar system.Remove all loose and unsound concrete by hammerand chisel. Remove small concrete pieces with awire brush. Remove loose rust scale and all 4.3.7.10 Bonding Toppings to Existing Concrete.nonadherent rust from any exposed reinforcing by Use a 2-part epoxy concrete adhesive to bond con-chipping with handtools and by wire brush. Clean crete toppings to existing concrete floors. Removeall dust, oil, or other bond-inhibiting materials from all dust, laitance, oil, and other deleterious materialpatch area. Be sure depth of patch area is from the existing concrete slab by sandblasting orcompatible with patching material. Before placing other means of abrasive cleaning available. Removethe patching material, thoroughly clean, dampen, all standing water from the area to be covered. Mixand brushcoat the area to be repaired. Mix only the only the amount of adhesive that can be usedamount of mortar that can be used during the pot during the pot life of the specific product. Applylife of the specific product. Patch area with poly- the adhesive with airless sprayer, roller, brush, ormeric repair mortar. All surface preparation, squeegee evenly to the surface at the coveragemixing, and placing must be in strict accordance specified by the manufacturer. All surfacewith the manufacturer's printed instructions. All preparation, mixing, and application of the adhesivework must be finished plumb, smooth, and neat to must be in strict accordance with thematch adjacent existing areas. Protect the repair manufacturer's printed instructions.and keep it damp for the curing period specified bythe manufacturer.

4.3.7.8 Structural Concrete Patching. Repair polymeric mortar overlay. Prepare surface to bedefective or discolored concrete with a 2-part poly- covered to the required profile of the specificmeric mortar system. Remove concrete in question product to be used. Remove all deterioratedto a depth of no less than 1 inch. Make all cuts concrete and existing toppings, dirt, oil, and otherperpendicular to the concrete surface. Remove all bond-inhibiting materials by sandblasting, scabbler,loose concrete pieces with a wire brush. Before or other available means. Sweep or vacuum dustplacing patching material thoroughly clean, off entire surface. Repair all cracks in the existingdampen, and brushcoat the area to be repaired. Mix slab with a low viscosity epoxy grout. Wash entireonly the amount of mortar than can be used during surface prior to overlay application and allow it tothe pot life of the specific product. Patch area with air dry. Apply overlay mortar to the surface andpolymeric repair motar. All surface preparation, finish to the desired final surface condition. Allmixing, and placing must be in strict accordance surface preparation, mixing, placing, and finishingwith the manufacturer's printed instructions. All must be in strict accordance with the manufacturerwork must be finished plumb, smooth, and neat to s printed instructions. Provide joints in the overlaymatch adjacent existing areas. Protect patch and topping in the exact location of joints in the exitingkeep it damp for the curing period. slab. Saw-cut joints immediately after overlay has

4.3.7.9 Grouting Bolts. Grouting bolts into exist-ing concrete beams, walls, and slabs using a 2-partepoxy grouting compound with an addedaggregate. Remove dust, grease, standing water,and all other deleterious materials from bolthole.Remove dirt and grease from the bolt and dry itsufficiently. Mix only the amount of grout that canbe used during the pot life of the specific product. 4.3.7.12 Surface Sealants. Protective surface coat-Fill the bolthole to a predetermined depth with ings are used primarily to improve the durability ofepoxy grout. Set the bolt in the hold and work it up concrete by preventing or inhibiting the intrusion ofand down, lightly tapping it to insure complete moisture, chemicals, or waterborne salts but canembedment. Check the bolt projection and also be used to lengthen the life of repair. Typicalplumbness and secure in position using a template materials employed as protective surface coatingsto insure proper location. Pack or pour additional include boiled linseed oil generally mixed with

vertical and overhead surfaces. All surfacepreparation, mixing, and application of groutingcompound must be in strict accordance with themanufacturer's printed instructions.

4.3.7.11 Concrete Floor Overlays. Refinishexisting concrete floor slabs using a 2-part

set or preform joints by inserting steel or plasticstrips in the existing joints. Preformed joint stripsshall not project above the top of the overlay andshall be removed after the overlay has stiffened.Tool a c-inch radius edge after the joint strip isremoved. Protect the new overlay and keep it dampfor the curing period specified by the manufacturer.


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mineral or petroleum spirits or turpentine), 351 and should not contain more than 8-percentpetroleum oil, silicones, epoxy-resin coatings, as- free (unhydrated) calcium oxide and magnesiumphalt materials, rubber and rubberized asphalt, or oxide. Lime paste, after soaking as recommendedcuring compounds. Epoxy coatings are the most ef- herein, should pass the plasticity test for Type Ffective under sustained exposure because they do lime given in Federal Specification SS-L-351. Sandnot require replacement as frequently; but they are should be sharp, clean, and free from dirt, silt,more expensive. Impervious coatings such as organic matter, and other impurities. Mixing waterepoxy-resin coatings should never be applied to the should be clean freshwater and free from excesssurface of concrete slabs on grade that may be acids, alkalies, and other deleterious matter.subsequently exposed to freezing unless it is certainthat the concrete can resist frost action in a criti-cally water-saturated condition.

a. Methods of Application. Sealers may be ap- Porous soft brick should be wetted before laying inplied to old surfaces by airless spray, roller, brush, hot, dry weather to reduce the rate of absorption oflamb's wool applicator or trowel, depending on the water from the mortar. The amount of wetting isproduct. High viscosity sealers such as bituminous determined by the type of brick and the weatherapplications for below-grade concrete exteriors are conditions. Glazed brick has little or no absorption;generally applied with brush or trowel and may therefore, it should be laid dry. Lay the brickworkrequire reinforcing mesh to enhance resistance to in the bond that matches the adjoining existingtear or rupture. Some epoxy, rubber, and acrylic work. Use batts only for closures. Completely fillsealants may be applied by airless spray equipment. all joints between bricks with mortar. Form bedMost sealants may be applied by brush or lamb's joints with a thick, smooth layer of mortar. Avoidwool application. The manufacturer's recommended furrows. Form cross joints by applying a full coatapplications should always be followed. of mortar to the entire side or end of the brick to be

b. Surface Preparation. Sealants require cleansurfaces for proper penetration. Surfaces should befree of existing coatings, dirt, oil, grease, or othercontaminants. The type of sealant selected will de-termine the appropriate method for cleaning. Par-ticular care must be taken in cleaning surfaces forapplication of epoxy sealants or films, which re-quire water or sandblasting. The manufacturer willidentify the appropriate cleaning methods which aredetailed in paragraph 4.3.9.

4.3.8 Brick Repairs place. Do not allow any dry or butt joints. Build in

4.3.8.1 Mortar Preparation. Lay new brickworkin mortar mixed in the proportions by volume of 1part portland cement, 1 part lime paste, and 6 partssand, or of 1 part masonry cement and 3 parts sand.Add sand so that it is distributed uniformlythroughout the mass. Then add water graduallyuntil the mortar is plastic enough for use. Portlandcement and masonry cement (type II) shouldconform to ASTM Specification C-270. Lime pasteshould be made with pulverized quicklime or withhydrated lime that has been allowed to soak for atleast 72 hours before use. However, hydrated limeprocessed by the steam method should be soakednot less than 12 hours before using it. Pulverizedquicklime should conform to Military SpecificationMIL-L- 14519C. Ten percent should pass a No.20sieve, and 90 percent should pass a No.50 sieve.The chemical composition and fineness of hydratedlime should conform to Federal Specification SS-L-

4.3.8.2 Bricklaying. Handle bricks so that theirfaces and edges will not be damaged. Be sure thatmasonry beds are clean and properly wetted.

laid, as the case requires, and then shove themortar-covered end or side tightly against thebricks already in place. Do not merely butter thecorners of the brick to be laid and then attempt tofill the empty mortar joints after the brick is inplace. Form longitudinal joints as recommended forcross joints or apply a full thickness of mortar tothe bricks laid previously, and then shove the nextbrick in place. Lay closure bricks with full-bed,longitudinal, cross joints, placing the brickscarefully without disturbing the bricks already in

metal fasteners, flashing, etc., as the work pro-gresses. Keep joints uniform in thickness, aligningand tooling them to match joints of existing work.Remove all loose and excess mortar.

4.3.8.3 Brick Walls. Common defects in brickwalls are open vertical joints, cracking, spalling,and porosity. Efflorescence and leakage of rain-water through the walls usually result from suchdefects. Inadequate or improperly designed andconstructed flashings also cause serious leakage.Open, vertical joints result from failure to fill thejoints with mortar in laying the brick. Cracking mayresult from settlement, expansion and contraction,misalignment, or some other serious structuraldefect in the building. Spalling results if bricks aresoft or tend to powder and crack, or when moisturefreezes within the masonry. Porosity in brick wallsis rare and can result only from the use of porousbrick or mortar. Mortar containing large aggregateor poor-quality brick may produce this porous


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condition. An engineering investigation of the buildings may have sections of masonry damagedcauses of structural defects should govern the or loosened at the corners. This occurs where thenature and extent of major repairs. Cracked and horizontal movement cracks along the side and endopen mortar joints should be repaired as of a building meet. Frequently, the horizontal crackrecommended. Where masonry cracks appear at not only continues around the corner, but alsowindows, doorways, offsets, and like places, an forms a diagonal crack in a downward directionexpansion joint or control joint should be provided that meets a similar crack from the other side,at those locations to minimize the effect of forming a"V." The masonry units inside this V arefoundation movement. loosened and must be reset. See figure 4-7. The

4.3.8.4 Racked-Down Corners. On masonryprojects having concrete floor or roof slabs,

following procedure may be used to accomplish therepair:

a. Remove all the bricks inside this V, 4.3.8.5 Parapet Creep. Unequal expansion of roofincluding any masonry units that have been broken. slabs and masonry parapets sometimes causesSee figure 4-7. This forms regular sides and helps parapet corners to creep. When this happens, theto hold or key the new masonry units in place. horizontal mortar joint at the top of the slab (or the

b. After the masonry units are removed, thegood masonry units should be cleaned and as manynew matching ones obtained as necessary. Relaythe bricks in mortar up to and even with thehorizontal crack running along the side and end ofthe building. Making all joints the same width asthe original joints matching the old mortar willresult in a very presentable job. As the masonryunits are relaid, the backup masonry units should becoated with mortar, so that the newly laid masonryunits will be bonded to them.

c. Partially fill with mortar the top joint that is Through-wall metal flashing and a continuous sealon line with the horizontal crack. This can be done of bituminous plastic cement must be provided atby pushing the mortar into the joint with a narrow the bottom of and in the expansion joint. Plasticpointing trowel. When about half the depth of the cement should conform to Federal Specificationjoint is filled, fill the remainder with sealing SS-C-153.compound. This system of mortaring only half ajoint supports the brick above but forms a weakplane along the top of the racked-down areas. Ifmovement occurs the mortar joint break but therelaid bricks remain in place. The sealingcompound keeps the joint watertight.

nearest through-wall flashing) usually shears open.The corner parapet will then extend beyond theface of the wall below. If creeping continues to thepoint that cracks extend through the parapet andconcrete spalls from the spandrel beam, and bothbrick and mortar begin to break off, an engineeringinvestigation for major repairs is necessary. In mostcases, approximately 20 feet of the parapet,beginning at the corner, must be removed. A newsection of parapet, doweled into the wall below, isthen laid. A vertical expansion joint, 1 inch wide, isprovided at the juncture with the existing parapet.

4.3.9. Cleaning Masonry and Concrete Walls

4.3.9.1 General. The appearance of many struc-tures has been irreparably marred by impropercleaning methods. A cleaning method that workswell on hard surfaces can be harmful to soft stone


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and glazed finishes. A method that cleans marble or each cleaning nozzle is necessary. The pressureglazed surfaces may be entirely unsatisfactory on with which the steam and water mixture is drivenrough-textured surfaces. Cleaning methods safe for against the wall, not volume of discharge, is im-a masonry surface may cause damage to the mortar portant in steam cleaning.joints. If the surface to be cleaned has more thanone kind of masonry, one cleaning method may notbe safe or effective on all. The material to becleaned and the type of stain to be removed willdetermine the cleaning process to be used.

4.3.9.2 Concrete. Many chemicals can be applied spray at a high velocity. Operating two cleaningto concrete without causing injury. Chemicals nozzles from each length of scaffold is goodhaving an acid reaction must be handled with cau- practice.tion. Even weak acids may roughen the concretesurface if left for long periods of time. Stainscaused by iron, cooper, bronze, aluminum, fire, andoil are discussed below. Old long-neglected stainsmay require repeated treatments. Deep staining (4) Steam Supply Line. Use high-pressuremay be removed with a poultice or by the steam couplings and hose, or suitable pipe and fit-"bandage" treatment. tings, or a combination or both, to convey steam to

4.3.9.3 Masonry. Masonry units of low absorptionand those with smooth (or glazed) surfaces (5) Rinsing Hose. In addition to the hosegenerally respond readily to proper cleaning supplying water to the steam-cleaning nozzle, havemethods and resume their original appearance. another hose with ordinary garden-type nozzle andHighly absorbent or rough-surfaced units are more shutoff to flush the walls with water occasionally.difficult to clean. When the staining material fillsthe pores of the unit, attempts to remove the stainmay remove part of the surface, destroy its texture,or change its appearance. The principal methods ofcleaning masonry structures are with steam andwater, sandblasting, and various liquids and pastes.

4.3.9.4 Steam Cleaning. Cleaning with high-pres- neous matter, which is later flushed down the wallsure steam and water, sometimes called cold-steam by the rinsing hose. Experimentation with thecleaning, is effective and economical. It removes cleaning equipment quickly shows the operator thegrime from surfaces of concrete and masonry best angle and distance to hold the nozzle from thebuilding without harming the surfaces. After steam wall and proper regulation of steam and wet valuescleaning, masonry surfaces retain their original for most effective work. Work on one 3-foot-finish and natural color tones without the square space at a time. Pass the nozzle back androughened surfaces and dulled edges caused by forth over the area; then flush with clear watersandblasting or the dead, bleached tone caused by before moving to the next space. Alkalines, such asacid cleaning. sodium carbonate, sodium bicarbonate, and trisodi-

a. Equipment. Use proper equipment forsteam cleaning. Much of it can be improvised, butthe needs of an installation may make buying orrenting equipment advantageous.

(1) Steam Supply. A continuous supply of units thoroughly with clear water before beginninghigh-pressure steam must be assured before the cleaning operation. Immediately after cleaning,cleaning operations begin. A truck-mounted wash the wall with enough clear water to removeportable boiler, together with its accessories, is all possible salts from the wall face. Removal ofgenerally a satisfactory source. Steam pressure for surface dirt sometimes reveals stains. A mild acidcleaning old buildings is preferably 150 lb/in and wash may be necessary to remove them. After the2

never less than 140 lb/in . For cleaning new work stains are removed, steam the treated surface again2

120 lb/in is preferred; however, never less than and flush with water from the rinsing hose to2

100 lb/in is needed. Boiler capacity of about 12 remove all trace of acid wash. Steel scrapers or2

horsepower for wire brushes may be necessary to remove hardened

(2) Nozzle. The cleaning nozzle is a mostimportant accessory; it should be a mixing type,having a water control valve and automatic steamshutoff. One efficient type has a very narrow open-ing 4 inches long and can deliver an extremely fine

(3) Water Supply Hose. An ordinary gardenhose is suitable for carrying water from the sourceto the mixing nozzle.

the mixing nozzle.

b. Procedure for Steam Cleaning. Cleaning isdone by high-velocity projection of a finely dividedspray of steam and water against the masonry sur-face. The mixture of steam and water spray enter-ing minute surface depressions and openings dis-solves and dislodges grime, soot, and other extra-

um phosphate, are sometimes added to the cleaningwater to speed the cleaning action. Although theyaid cleaning, some salts are retained in the masonryand may appear on the wall later as efflorescence.To cut down the amount of salts retained, wet wall


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deposits that cannot be removed by steam cleaning. determine how far to stand from the wall, whichUse scrapers sparingly and carefully to avoid pressure is best, and the angle at which sand willdamage to masonry surface. Use brushes of fine clean the surface, but not etch it. The operatorspring-steel wire to grind off the hard deposit should concentrate on hitting the brick surfaces,without digging into or scratching the masonry and not the mortar joints. When hardness betweensurface. After hard deposits have been removed by masonry units and mortar joints differs widely,scraping or wire brushing, flush off surface with sandblasting may cut deeply into the mortar. If thiswater, treat it with the steam-cleaning nozzle, and occurs, joints must be repointed. Roughenedflush again to remove any loose dirt which might surfaces produced by sandblasting gather soot andcause future streaking or discoloration. dirt quickly; therefore, the application of a trans-

4.3.9.5 Sandblast Cleaning. Sandblasting cleansrust and scale from structural steel and many othermetal surfaces efficiently. When used on masonrysurfaces, it eliminates mortar smear, acid burn,efflorescence (which is inherent in acid cleaning), 4.3.10 Chemical Cleanersand chemical stains. Do not use this method onmarble, terra cotta, glass, or units with glazed orother special surfaces or textures. Although itcleans effectively, it often destroys the originalsurface of the masonry unit. It tends to dull sharpedges (arrises), to blur ornamental detail andcaring, and to roughen surfaces. Stone cleaned bysandblasting, especially limestone, appears whiter,but this whiteness is caused partly by the fact thatthe stone surface has been abraded.

a. Equipment Used for Sandblasting Use a ¾-inch hose if maximum air and sand pressure is re-quired, or a 1-inch hose if volume, rather thanpressure, is required. For use against brick, a pres-sure in the range of 60 to 120 lb/in through a ¼-2

inch sandblast nozzle is recommended. The qualityof sand needed varies with the depth of cutting tobe done and the type of material to be cleaned.Fine, white urn sand, which is rounder and cuts lessthan sharp sand, is recommended for use on brick.Placing a canvas screen around the scaffold keepssand from scattering and makes it possible tosalvage about 75 percent of the sand. Usually, fourmen are required in a sandblasting crew: oneattends the air compressor, one at the nozzle, andtwo on the ground to handle the hose, scaffold,sand, etc.

b. Procedure for Sandblasting In sandblasting,compressed air forces sand through a nozzleagainst the surface to be cleaned. The sand re-moves accumulated grime and a layer of the sur-face. The thickness of the layer removed dependson the type of sand used, the air pressure, thevolume of sand applied, the nearness of the nozzleto the surface, and the length of time that the sandis applied to one area. Sandblasting can be usedsafely on hard brick by an experienced operatorusing caution, and on sand finish with extremecaution. The nozzle operator should experimentwith his equipment on a small, secluded area to

parent waterproofing is desirable. This coating fillssurface pores, tends to make the wall self-cleaning,and prevents rapid soiling of surface by smoke anddust.

4.3.10.1 General. Acid and caustic concentrationsand space mixtures are used to clean many interiorand exterior surfaces. The cleaning material useddepends on the texture of the surface to be cleaned,the age of the structure, the material or stain to beremoved, and the capabilities of the cleaning crew.The most satisfying results will be obtained bybalancing all the above factors and observing a trialapplication on a sheltered area. Many burned-claysurfaces, concrete surfaces, and glazed (orpolished) surfaces of tile, marble, and glass can becleaned by hand-scrubbing with a white soappowder dissolved in soft water, using ordinary fiberscrub brushes. Rinse surfaces thoroughly with clearwater after scrubbing them.

4.3.10.2 General Precautions in Using Acids.Do not use acid solutions to clean limestone andsimilar materials unless experienced operators andexpert supervision are available. Acid washes tendto eat into stone surfaces and pit them. They usu-ally bleach, producing an unnatural appearance, andmay cause yellow stains to appear later. If acidsolution is not thoroughly washed from themasonry pores after cleaning, the destructive actioncontinues for some time. When mixing acidsolutions, always pour acid into water. Handle acidsolutions carefully because they are harmful to theskin and especially to the eyes. When working withacid cleaners, wear goggles, gloves, and protectiveclothing, and keep a supply of running water athand. Use only wooden containers and fiberbrushes when cleaning with acids. Do not use metalcontainers or wire brushes and steel wool to scrubthe walls because small steel particles becomelodged in crevices, producing rust spots and stains.

4.3.10.3 Removing Mortar Stains.

a. General Cleaning Procedure. Make thecleaning operation one of the last phases of the job.Do not start before the mortar is thoroughly set and


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cured. Remove large particles of mortar with second method for cleaning is the method describedwooden paddles and scrapers before wetting the for cleaning light brick with an acid solution,wall. In some cases it may be necessary to use a paragraph 4.3.10.3(d), using no more than 1 partchisel or wire brush. Presoak the wall. Saturate the high-grade acid (chemically pure) to 25 parts cleanmasonry with clean water and flush off all loose water. Never use acid to clean salt-glazed ormortar and dirt. Protect the area below the surface metallic-glazed masonry units.being cleaned. Keep all masonry below soaked withwater and flush off all acid and loose mortar.Protect ornamental shrubs and pedestrians, asrequired. Clean only a small area at a time(approximately 10 to 20 square feet). It may benecessary to reduce this area when heat, sunlight,warm masonry, or warm winds increase the reac-tion rate of the acid or accelerate drying. Rinse thewall thoroughly with plenty of clean water afterscrubbing.

b. Cleaning Dark- and Light-Colored Brickwith Nonacid Solution. Follow directions outlinedin paragraph 4.3.10.3(1), General CleaningProcedure. Scrub wall with a solution of ½-cuptrisodium phosphate and ½-cup household 4.3.10.4 Paints and Similar Coatings.detergent, dissolved in 1-gallon clean water. Usestiff fiber brush only.

c. Cleaning Dark Brick with Acid Solution. water paints, wash the surface with an acid solutionAcid cleaning should be used only in difficult cases. of 1 part muriatic acid and 5 parts water. ScrubFollow directions outlined in paragraph 4.3.10.3(a), vigorously with a fiber brush as the solution foams.General Cleaning Procedure. Mix 1 part clean, When coating has been removed, wash the wallstain-free commercial-grade, hydrochloric acid with water from an open hose until all traces of(muriatic) with 9 parts clean water in a nonmetallic acid are removed. If a paint film is old, crumbling,container. Pour acid into water; never pour water and flaking, scraping with wire brushes and metalinto acid. Apply and scrub the brick with a long- scrapers may be necessary. While this method ishandled fiber brush having no metallic parts. effective, it may leave metal particles, which later

d. Cleaning Light Brick with an AcidSolution. Use the same procedure as for cleaning b. Oil Paint, Enamels, Varnishes, Shellacs,dark brick, except mix 1 part of the highest grade and Glue Sizings. Remove oil paint, enamel,acid (chemically pure) available to 15 parts clean varnish, shellac, or glue sizing by applying a paintwater; then neutralize the acid immediately after remover that is left on until the softened paint cancleaning. Neutralizing can be accomplished by be scraped off with a knife or flushed off withflushing the wall with a solution of potassium water. After the paint is removed, wash the wallhydroxide or sodium hydroxide, mixed at the rate thoroughly to remove all traces of acid. Efficientof ½ pound of hydroxide in 1 quart of water (2 paint removers include:lbs/gal). Allow this solution to remain on the wallfor 2 or 3 days. The white salts left on the wall bythe hydroxide may be hosed off or will be removed (2) Trisodium phosphate — 2 pounds to 1by a heavy rain. gallon of hot water.

e. Cleaning Glazed Brick and Tile. Glazed (3) Caustic soda—2½ pounds to 1 gallonbrick and tile should be carefully wiped clean with hot water.a soft cloth within a few minutes after laying. Afinal cleaning with a soft sponge or brush andample water will usually do the job. In moredifficult cases, use the same procedures as used forcleaning dark- and light-colored brick with nonacidsolutions, paragraph 4.3.10.3(b); do not use metal (5) Soda ash and quicklime—equal partscleaning tools, brushes, or abrasive powders. A mixed with enough water to form a thick paste.

f. Efflorescence Stains. Follow the stepsoutlined in paragraph 4.3.10.3(a), General CleaningProcedures. Efflorescence can frequently beremoved by water applied with a stiff scrubbingbrush. In those cases where the water proceduredoes not remove all the stain, the surface can bescrubbed with a solution of hydrochloric (muriatic)acid mixed at the rate of 1 part commercial-gradeacid to 9 parts water.

g. Vanadium Stain. Green stains are usuallycaused by salts of vanadium and can be removed bythe method for neutralizing described in paragraph4.3.10.3(d).

a. Whitewash, Calcimine, and Cold-WaterPaints. To remove whitewash, calcimine, or cold-

cause rust stains in the wall surface.

(1) Commercial paint remover.

(4) Sodium hydroxide—1 part dissolved in3 parts water and added to 1 part mineral oil. Stirmixture until emulsified; then stir in 1 part sawdustor other inert material.

Leave this mixture on the wall for 24 hours before


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scraping off. if the oil-paint is very thick and hard, phate-chlorinated-lime solution. Fold a whitethis method may fail, in which case sandblasting or canton flannel cloth to three or four thicknesses,burning may be the best way to remove it. and saturate with the liquid. Paste this saturated

4.3.10.5 Iron Stains. Iron stains can usually berecognized by their resemblance to iron rust or bytheir proximity to steel or iron members in thebuilding. Large areas of concrete or cement stuccomay be stained if curing water contains iron. Thisstain can generally be removed by mopping thesurface with a solution of 1-pound oxalic acid dis-solved in 1-gallon water. After 2 or 3 hours, rinsewith clean water, scrubbing at the same time withstiff brushes or brooms. Some spots may require asecond mopping and scrubbing. For older, deeperstains the following methods are recommended:

a. Method 1. Dissolve 1 part sodium citrate in6 parts lukewarm water. Mix thoroughly with 7parts lime-free glycerin. Add to this solutionenough whiting (chalk powder) or kieselguhr tomake a paste poultice stiff enough to adhere to thesurface when applied with a putty knife or trowelto a thickness of ½ inch or more. Allow a minimumof 2 days for drying. Scrape off and washthoroughly. If the stain has not disappeared, repeatthe treatment. This treatment has no injuriouseffects, but its action may be too slow for badstains. Ammonium citrate produces quicker results,but may injure a polished surface slightly, makinga repolishing necessary.

b. Method 2. The sodium hydrosulphitecombination "bandage practice" method is moresatisfactory for removing deep, intense iron stains.Make a solution by dissolving 1 part sodium citratecrystals in 6 parts of water. Dip white cloth orcotton batting in this solution, place the cloth overthe stain, and leave it there for 15 minutes. On hori-zontal surfaces, sprinkle a thin layer of hydrosul-phite crystals over the stain being treated withsodium citrate, moisten with water, and cover witha paste of whiting and water. Give vertical surfacesthe sodium citrate treatment. Place layer of whitingpaste on plasterer's trowel, sprinkle on a layer ofhydrosulphite crystals, moisten slightly, and applyto stain. Remove treatment after 1 hour. If left onlonger, a black stain may develop. Wash treatedsurface with clean water. If inspection showsincomplete removal of the iron stain, repeat thecleaning operation, using fresh materials.

4.3.10.6 Fire and Smoke Stains.

a. Method 1. Fire and smoke stains can some-times be removed by scouring with powderedpumice or a grit scrubbing powder. After removingthe surface stain by scouring, the deep-seated staincan be removed by applying the trisodium-phos-

cloth over the stain, and cover with a slab of con-crete or sheet of glass, making sure the cloth ispressed firmly against the stained surface. If thesurface is vertical, devise a method to hold thesaturated cloth firmly against the stain. Resaturatethe cloth from time to time. Wash surfacethoroughly at end of treatment.

b. Method 2. Make a smooth stiff paste oftrichlorethylene and powdered talc and apply as atroweled-on poultice. Cover poultice with glass orpan to prevent rapid evaporation. Allow time todry. Scrape off and wash away all traces of treat-ment material. Trichlorethylene gives off harmfulfumes; therefore, see that closed spaces are wellventilated when using this stain remover.4.3.10.7 Copper and Bronze Stains. Copper andbronze stains are usually green, but may be brownin some cases. Mix 1 part dry ammonium chloride(sal ammoniac) and 4 parts powdered talc, addwater, and stir to a thick paste. Trowel ¼-inchlayer of paste over the stain and leave until dry.When working on polished marble or similar finesurfaces, use a wooden paddle to scrape off driedpaste. An old stain may require several applica-tions.4.3.10.8 Oil Stains. Oil penetrates most concretereadily. Oil spilled on horizontal surfaces should beimmediately covered with a dry powdered materialsuch as hydrated lime, fuller's earth, or whiting.Sweep up the powdered material, taking as muchof the oil as possible. Scrub with a 10 percent acidsolution (phosphoric or muriatic) containing adetergent, and wash with water. If treatment ismade soon enough, there will be no stain. How-ever, when oil has remained for some time, one ofthe following methods may be necessary:

a. Method 1. Mix 1 pound trisodiumphosphate in 1 gallon water, and add sufficientwhiting to make a stiff paste. Spread a layer of ½-inch thickness over the surface to be cleaned.Leave paste until it dries (about 24 hours), removeand wash surface with clear water.

b. Method 2. Saturate white canton flannel ina mixture of equal parts of acetone and amylacetate and place it over the stain. Cover the clothwith a slab of dry concrete or sheet of glass. If stainis on a vertical surface, improvise means to holdcloth and covering in place. Keep the clothsaturated until the stain is removed. Coveringsaturated cloth with glass tends to drive the stainin, while the slab of dry concrete will draw outsome of the oil.


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4.3.10.9 Ink Stains. thick paste is obtained. Apply it with a trowel as a

a. Blue or Black Ink& Stains from differenttypes of inks require different treatments. Becauseof their acid content, ordinary writing inks mayetch concrete. To remove a stain of this type, makea strong solution of sodium perborate in hot water.Mix it with whiting to form a thick paste. Apply itin a ¼-inch layer, and leave until it is dries. if someof the blue color is visible after the poultice isremoved, repeat the process. If only a brown stainremains, treat it by Method 1 recommended foriron stains. Sodium perborate may be obtainedfrom any druggist. Some blue inks contain Prussianblue, a ferrocyanide of iron. These stains cannot beremoved by the perborate poultice, Javel water, or 4.3.10.11 Urine stains. To remove urine stains,chlorinated lime poultice. They yield to treatment use the method recommended for tobacco stains. Ifby ammonia water applied on a layer of cotton the stains remain, saturate cotton batting in thebatting. A strong soap solution applied in the same liquids recommended, and paste it over the re-way may also be effective in some cases. maining stains. Resaturate the cotton, if necessary.

b. Bright-Colored Inks. Many red, green, 4.3.10.12 Rotten Wood Stains. Damp rotten woodviolet, and other bright-colored inks are water will produce a chocolate-colored stain that is read-solutions of synthetic dyes. Stains made by this ily distinguished from most other stains. Thetype of ink can usually be removed by the sodium treatment recommended for fire stains is best. Re-perborate poultice that is recommended for moval of the stain will be accelerated if the surfaceordinary writing ink stains. Often the stain can be is first scrubbed thoroughly with glycerin dilutedremoved by applying ammonia water on cotton with four times its volume of water.batting. Javel water, conforming to FederalSpecification 0-S-602, may be used in the sameway as ammonia water, or mixed to a paste withwhiting and applied as a poultice. A mixture ofequal parts of chlorinated lime and whiting reducedto a paste with water can also be used effectively asa poulticing material. Use a chlorinated lime 4.3.10.14 Iodine Stains. Iodine stains graduallyconforming to the requirements of Federal disappear; however, they may be removed quicklySpecification 0-C-114 for Type II, Grade A by applying alcohol and covering the spot withchlorinated lime. whiting or powdered talc. If the stain is on a verti-

c. Indelible Inks. Many indelible inks consistentirely of synthetic dyes. Stains may be treated asrecommended for that type; however, some indel-ible inks contain silver salts, which cause a black 4.3.10.15 Perspiration Stains. Secretions from thestain. This stain can be removed with ammonia hands or oil from the hair may produce stains onwater applied by bandage. Several applications are concrete. The stain is brown or yellow and may beusually necessary. mistaken for an iron stain. The best treatment is the

4.3.10.10 Tobacco Stains. The following methodis usually effective in removing tobacco stains. Dis-solve 2 pounds of trisodium phosphate crystals, 4.3.11 Glass-Block Masonryconforming to Federal Specification O-S-642, in 1gallon of hot water. In a shallow, enameled pan,mix 12 ounces of chlorinated lime, with enoughwater to make a paste. Add the water slowly andmash the lumps as they form. Pour this mixture andthe trisodium phosphate solution into a 2-gallonstoneware jar, and add water until the jar is full.Stir well, cover the jar, and allow the lime to settle.Add some of the liquid to powdered talc until a

¼-inch poultice. To apply the paste with a brush,add about a teaspoon of sugar to each pound ofpowdered talc. When it is dry, scrape it off with awooden paddle or trowel. This mixture is a strongbleaching agent and is corrosive to metals. Careshould be taken not to drop it on colored fabrics ormetal fixtures. If the stain is comparatively light,use a scrubbing powder as a poulticing material.Stir the powder into hot water until a mortarconsistency is obtained. Mix it thoroughly, and thenapply the mixture to the stained surface in a ½-inchlayer. Permit it to dry. In most cases, make two ormore applications, if necessary.

4.3.10.13 Coffee Stains. Coffee stains can be re-moved by applying a cloth saturated in glycerin thatis diluted with four times its volume of water. Javelwater of the solution used on fire stains is alsoeffective.

cal wall, it may be removed by applying some alco-hol to the stain and covering it with a paste oftalcum and alcohol.

one recommended for fire stains. Deep stains mayrequire several treatments.

4.3.11.1 General. Glass-block panels require littlemaintenance other than occasional cleaning andperiodic inspection of joints. Theglass-block panelscan be seriously damaged by superimposed loadstransmitted through excessive deflections in beamsand lintels, differential settlement of foundations, orby impact. The cause of serious damage must beinvestigated and corrected prior to making repairs.


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4.3.11.2 Materials. The following materials are Reinforcing ties shall be spaced so as not to occurused in glass-block masonry: in the top joint of panels. Place the lower half of the

a. Glass block is a hollow, partly evacuatedblock constructed of translucent, pressed glass,which is formed of two halves fused together at ahigh temperature. The exposed faces are a nominal6-inch (5¾ inches), 8-inch (7¾ inches) and 12-inch(11¾ inches) square with a nominal 4-inch (3finches) thickness.

b. Mortar should conform to N-type mortar asdescribed in ASTM C-270. A waterproofing mix-ture approved by the glass-block manufacturer maybe used with the mortar.

c. Oakum shall be a nonstaining type treatedto prevent mildew and dry rot.

d. Premolded expansion strips shall be of d-inch-thick fibrous glass material or other materialrecommended by the glass-block manufacturer.

e. Joint reinforcement shall be fabricated ofgalvanized wire consisting of two 9-gauge parallelwires spaced 2 inches on centers with a 14-gaugecross wire welded at not more than 8 inches oncenters.

f. Wall anchors shall be perforated (hot-dipgalvanized after perforation), 20-gauge, steel strips.

g. Asphalt emulsion shall be the type andmanufacture recommended by the glass-blockmanufacturer.4.3.11.3 Installation of Glass Blocks.

a. General. Good workmanship is essential toobtain watertight glass-block panels. Manufactur-er's instructions and recommendations should becarefully studied. Minor deviations are permissiblebut should be for a good, valid reason.

b. Procedure. The sill area to be covered withmortar shall receive a heavy coating of asphaltemulsion not less than ¹/ inch thick. When the16emulsion coating is thoroughly dry, place a fullmortar-bed joint. Do not furrow the mortar bed.Place the expansion strip in the jamb and headusing asphalt emulsion as an adhesive. Set the firstcourse of block. All joints must be full and notfurrowed. Do not use steel tools to tap blocks intoposition. Blocks shall be laid in a regular straight-line pattern with vertical and horizontal jointscontinuous. Horizontal joint reinforcing shall beinstalled where indicated, or in accordance with thefollowing General. rule:

— For blocks 6 inches square, one tie everyfourth course.

— For blocks 8 inches square, one tie everythird course.

— For blocks 12 inches square, one tie everysecond course.

mortar-bed joint. Press the reinforcing tie intoplace. Cover the panel reinforcing with the upperhalf of the mortar bed and trowel smooth. Panelreinforcing must run from end to end of the panel.Endlaps shall not be less than 6 inches. Reinforcingmust not bridge expansion joint. Wall anchors foranchoring the glass block to the masonry orconcrete construction shall be spaced not morethan 2 feet on centers, vertically. Panels up to 2feet high may have a single anchor in each jamb. Allpanels more than 2 feet high shall have at least twoanchors in each jamb. Anchors shall be crimped atjambs to provide for expansion and contraction.Anchors shall extend not less than 10 inches intothe structural jamb and 1 foot into the glass-blockjoint and shall be completely bedded in the centerof the mortar joint. While mortar is still plastic,joint shall be raked back a sufficient depth toexpose the edges of the block as sharp, clear lines.While mortar is still plastic and before final set, thejoints shall be tooled slightly concave and smooth.The recess left between the face of the glass-blockpanel and the structural jamb (or head openings)shall be rammed full with oakum to within e inchof the exposed surface of the glass block. Therecess grooves left in front of the oakum shall befully caulked on both interior and exterior toprovide a watertight and weatherproof joint. Rakeout other spaces requiring caulking to a depthequal to the width of the space. Remove surplusmortar from the faces of the glass block and wipedry.

4.3.11.4 Repair of Glass-Block Masonry. Glass-block masonry panels require little maintenanceother than occasional cleaning and periodic inspec-tion of joints, except when damaged. The causes ofdamage must be corrected before repairs are made.To repair panels, use the following methods:

a. Remove cracked and broken glass blocks.b. Chip off fragments of broken glass adhering

to undamaged blocks, taking care not to damagewall ties and anchors.

c. Clean old mortar from exposed wall tilesand anchors and from mortar-bearing edges ofadjoining blocks.

d. Replace panels using materials and methodsthat match existing work as closely as possible.Mortar will be proportioned with 1 part portlandcement and 1 part lime putty and 4 parts sand. Twoparts mortar cement may be substituted forportland cement and lime. Mix the mortar to stiffbut workable consistency. Mortar for glass blockmasonry should be drier than for brick masonry.


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SECTION IV—METAL SIDING

4.4.1 General the panel with a matching substitute. Buildings that

The type of material used for metal siding mayvary; but, generally speaking, each type requiressimilar maintenance and repair measures. Underconditions of foundation settlement, heavy windand snow loading, heavy falling objects, and colli-sion by vehicles, it is possible for metal buildings tosag, lean, or become damaged. In the event ofsettlement and subsequent misalignment of struc-tural members and displacement or bending ofsiding, it is necessary to correct the basic problemsas outlined in Chapter 2 of this manual. Wheresevere wind conditions or vibrations affect the sta-bility of metal siding, it may be necessary to place 4.4.3.1 General. Steel siding with protective coat-additional bracing and fasteners. This should be ings is designed to give reasonably long service.done as directed by a structural engineer or as Damage from abrasion may expose the steel core tooutlined in the siding manufacturer's instructions on corrosion or reduce the thickness of protectivesheeting and fasteners. coatings. Unless the damaged areas are repaired,

4.4.2 Routine Maintenance

Measures must be taken to keep all bolts, clips,rivets, nails, and other ties and fasteners tight andin place. Where corrosion has destroyed the effec-tiveness of a fastener, treat or replace it immedi-ately. Where stresses may have damaged the sidingconnection with the fastener, patch as necessarywith matching material and replace the connectorto assure a positive connection. Use stainless steelor aluminum nails and neoprene washers to assuretrouble-free service. They not only waterproof thejoint, but also prevent corrosion. It is oftenadvantageous from the standpoint of maintenanceto use double-headed nails in placing corrugatedmetal siding. Where sections of metal siding havebeen bent badly or cut, remove and straighten thesection, making neat and workmanlike patcheswhere expedient. Where damage is severe, replace

are subject to damage from vehicles should beprovided with bumper guards to prevent vehicles orforklifts from striking the siding. Where metalbuildings have interior insulation, take care not todamage existing construction and utilities whenrepairing or replacing metal wall coverings. Keepventilators in metal buildings clean and clear ofobstruction. Keep door-sliding devices and locks inadjustment and tightly fastened.

4.4.3 Steel Siding

touched up, or recoated as necessary, seriousdamage may result. If structural changes to abuilding make it necessary to cut existing steelsiding, treat the affected areas to prevent corrosion.Protected steel siding is of the standard corrugated(or deep corrugation types) with the steel coreprotected at the factory with coatings or acombination of coverings and coatings. See figure4-8. The sheets are resistant to flame spread. Thesurface is weather resistant, water repellent, andresistant to fumes, chemicals, and corrosion. Thecolor coats are stable to heat and light and resistantto chalking. Siding sheets are furnished, completewith all flashings, fastenings, and accessories.Interior and exterior surfaces of the sheets areprovided with a bituminous (black) or coloredsynthetic-resin, factory-applied weather surfacing.Protective coverings or coatings are applied by oneof the following methods.


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a. Type A (felt protected, zinc-adhesive). The 4.4.3.2 Cleaning of Steel Siding. Before repairing,cleaned steel core is dipped in a bath of molten touching up, or recoating, clean the affected areas.zinc, fusing the zinc to the steel. While the zinc is in Remove all flaked coating and rust with a stiff fibera molten state, a layer of unsaturated felt is pressed brush. Remove dust, chemical deposits, grease, andover it, on each side of the sheet, squeezing the felt dirt. Scrape off thick deposits of grease with afibers into the zinc. The exterior or interior surface trowel, putty knife, or wooden spade before usingis finished with a heavy bituminous compound or a the detergent cleaner. Remove rust with a wirecolor coating of synthetic resin. brush. The coatings for protected steel are pe-

b. Type B (felt protected, plastic-adhesive).The cleaned steel core is given a phosphatisingtreatment, coated with a rust inhibitive primer, anda resinous adhesive. A layer of impregnated felt isrolled onto both sides of the sheet with the appli-cation of heat and pressure. The sheet is then given 4.4.3.3 Repair of Steel Siding. To insure compat-a protective coating of bituminous compound or ibility, recoating compounds conforming to thealkyd-resin color compound. manufacturer's specification should be used in re-

c. Type C (Asphalt-protected, mineral-coated). The cleaned steel core is coated on allsurfaces with a rust-inhibitive coating. The sheet is a. Type A and B Materials. For small areasthen heated and coated with adhesive. After the (under 10 square inches) of steel core exposed,coated sheet has been cured, two separate coats of coat the exposed steel, including a width of aboutbituminous compound are applied. After 1 inch of the adjoining asbestos felt- andapplication of the second coat, a layer of mineral bituminous-covered surfaces, with asphalt primer.mica is applied to both sides of the sheet by heat Allow the primer to dry for at least 24 hours andand pressure. A synthetic-resin color coating may then apply bituminous plastic cement. Build up thebe applied over the bituminous-compound coatings. plastic cement to form a continuous plane with

troleum asphalt compounds. They can be softenedor dissolved by organic cleaners and solvents. Donot use naphtha, bensol, xylol, gasoline, or carbontetrachloride for cleaning protected steel. If asbes-tos felt is encountered, refer to paragraph 4.5.3.

coating protected steel. Recoating procedure is asfollows:


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adjoining surfaces. When the cement has been 4.4.3.4 Rusted and Loosened Fasteners. Replaceexposed to the weather for at least 24 hours, apply corrosion-weakened bolts and screws with newa coat of bituminous compound. Thin the bolts or screws. If the old holes are too large forcompound to brushing consistency with a suitable the new fasteners, drill new holes in an adjoiningsolvent and apply it at the rate of about 1 gallon to solid portion of the sheet. Use stainless-steel, sheet-125 square feet. Overlap adjoining area about 1 metal screws for fastening sheets to each other, andinch. For large areas (10 square inches or more) of use stainless-steel self-tapping screws to fastensteel core exposed, prime the metal surfaces and sheets to structural steel. Clean the rust from oldabout 1 inch of the adjoining areas as holes, cover them with muslin or fibrous glassrecommended for small areas. Then apply a brush patches, and recoat them as recommended forcoat of bituminous compound, using about 1 gallon repairing large areas of exposed metal core.for each 75 square feet. While the compound is stillwet, apply 48- by 48-mesh, unbleached muslinweighing 4 ounces per linear yard, or a porous,tough mat of fiberglass reinforced with randomcontinuous glass yarns and bonded with a resinousbinder compatible with bituminous coatings. Beforeusing muslin, soak it in clean water until all sizinghas been removed, and hang it up until it is dampdry. Apply the damp muslin or the fibrous glass matfirmly and evenly into the bituminous compound.Provide a continuous pleat in the muslin in thecenter of and parallel with each low corrugation ofthe protected metal roofing and siding. At side orend laps, pleat the muslin or the glass at the edges 4.4.3.6 Painting. Recoat or paint protected metalof the overlapping sheets of protected steel and if the existing coatings are dry and brittle and re-tuck the muslin or glass into the crevice between coating or painting will extend the life of the pro-the sheets. Immediately after the muslin or glass is tected metal for several years. Recoating or paint-installed, apply a brush coat of the bituminous coming should be done during warm weather. It shouldpound recommended for the first coat. Cover the not be done while it is raining or when the surfacesmuslin or glass completely. Allow this coat to dry are wet. Be sure the surfaces are clean. Type Cfor at least 24 hours. Then apply a final coat of the material cannot be painted or recoated unless thebituminous compound at the rate of 1 gallon for surface mica is removed or has disappeared. Refereach 75 square feet over the repaired area. to Tri-Services Manual, "Paint and Protective

b. Type C Material. For small areas (under 10square inches) of steel core exposed follow thetreatment recommended for Type A and B materi- 4.4.3.7 Unpainted Surfaces. If the existing sur-als, except that the final coat should be of asphalt- faces have not been painted, coat them with bitu-base emulsion. While the coating is still tacky, minous compound conforming to DODcover it completely with 160-mesh mica topping. Specification DOD-C-2687B. Before applying theFor large areas (10 square inches or more) of steel compound to dry and brittle surfaces, apply a coatcore exposed, prime the steel surface, including a of asphalt primer conforming to Federalwidth of about 1 inch of the adjoining bituminous Specification SS-A- 701. Allow the primer to drycovering, as recommended for smaller areas. Then for at least 24 hours. Thin the bituminousapply a brush coat of asphalt-base emulsion at the compound to brushing consistency with a suitablerate of 1 gallon for each 75 square feet. While the solvent. Use 4-inch paint brushes with coarse, stiffemulsion is still wet, apply muslin or fibrous glass bristles to apply the coating.mat as recommended for Type A and B materials.Immediately after the muslin or fibrous glass is in-stalled, apply a brush coat of the asphalt emulsion,covering the muslin or fibrous glass completely.Allow the emulsion to dry for at least 24 hours.Then apply a final coat of the emulsion at the rateof 1 gallon for each 75 square feet. While this coatis still tacky, apply an overall coat of 160-meshmica topping.

4.4.3.5 Caulking Side and End Laps. If water isentering the building through the laps, caulking ofthe laps is usually necessary. Before caulking,however, be certain that all fasteners in the vicinityof the leaks are tight. Remove all dirt and debrisfrom the laps. Using a caulking gun, lay acontinuous bead of plastic cement along the edgeof the protected steel siding. Then force the cementinto the lap with a putty knife or a small pointedtrowel. After the cement has been worked into thelap, smooth off the exposed cement and removeany excess cement.

Coatings" (TM 5-618, NAVFAC MO-110, AFM85-3).

4.4.3.8 Painted Surfaces. If the existing protectedsteel siding has been previously painted with alu-minum paint that has deteriorated or flaked off,repaint it with aluminum paint. Be sure to removeall loose and blistered paint before repainting. Forrepainting, use aluminum paint mixed in the pro-portions of 2 pounds of aluminum paste-pigment,Type II, Class B, to 1 gallon of Type 1, Class B,mixing varnish for aluminum paint. Apply the paint


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at the rate of about 1 gallon to 140 square feet. The back coating is a factory-applied, corrosion-Best results are obtained by spray applications inhibiting coating.rather than brushing. The use of brushes may causebleeding of the bituminous coating underneath. Iflocal conditions make brushing rather than sprayingnecessary, use a 3- or 4-inch, soft long-bristledbrush. Lay the paint on the surface, working in onedirection only. Work rapidly, do as little brushingas possible,.and do not brush the paint into thesurface. Follow the applicable portions of the Tri-Services Manual, "Paint and Protective Coatings,"in applying the paint. Be sure that all areas arecovered. Aluminum paint has a tendency to "leaf"immediately after it has been applied. Touching upan insufficiently painted area usually results in aspotty job.

4.4.4 Aluminum Siding Services Manual, "Paint and Protective Coatings."

4.4.4.1 General. Aluminum siding material coatedwith factory-laminated, polyvinyl-fluoride film isavailable as a protected metal siding. Aluminumunbacked lap siding 0.024 inch thick is bonded atthe factory with a laminated, polyvinyl-fluoride filmfinish not less than 1.5 mils thick on the face side.

4.4.4.2 Cleaning of Aluminum Siding. Before re-pairing, touching up, or recoating, clean affectedareas. Remove all loose or torn asbestos felt, flakedcoating, and rust with a stiff fiber brush. Removedust, chemical deposits, grease, and dirt. Usesynthetic detergent cleaner to remove chemicaldeposits and grease. Thick deposits of grease canbe scraped off before using cleaner. The coatings ofmost protected metal are petroleum asphaltcompounds that can be softened or dissolved byorganic cleaners and solvents. Do not use naptha,benzol, oxylol, gasoline, or carbon tetrachloride forcleaning protected metal. For further informationon cleaning aluminum surfaces, refer to the Tri-

4.4.4.3 Repair of Aluminum Siding. Minor repairsto the polyvinyl surface can be made with anenamel paint recommended by the siding manu-facturer. Extensively damaged siding should be replaced.

SECTION V — MINERAL AND CHEMICAL PRODUCTS

4.5.1 General covered with asbestos-cement shingles which must

Developments in combining chemical and mineralelements have produced hard-surfaced, weather-re-sistant materials for exterior wall finishes. Thesematerials require little maintenance except to keepfasteners secure and to remove stains acquiredfrom other sources. According to manufacturer'sinstructions, painting could be accomplished;however, military regulations prohibit doing itunless exception to policy is obtained.

4.5.2 Asbestos-Cement Siding 1979. With the passing of the Clear Air Act, the

Asbestos fibers have been found to be injurious tohealth when breathed under certain conditions. Asa result, some products such as asbestos fiber insu-lation and asbestos cement shingle siding have beenremoved from the market and laws exist restrictingtheir usage. Although these high visibility productshave been discontinued, asbestos and asbestosproducts continue to be manufactured and soldunder their trade names. Usage of these products isconsidered perfectly safe provided some caution isexerted, particularly with disposal. Any operationsuch as sawing, cutting, or pulverizing, whichmight create dust, should be avoided. Limitedcutting may be done when the operator wears adust mask and disposes of the residue without per-mitting it to become windborne. Since many mili-tary installations have large numbers of buildings

be retained, the following paragraphs pertaining toits handling are contained in this manual. At suchtime that the appearance and usage makesreplacement advisable, new siding of aluminum,steel, or vinyl with insulation should be installed asoutlined in appendix C.

4.5.3

Asbestos containing materials are found in varyingdegrees and locations in structures built through

use of sprayed on asbestos-containing friablematerials was banned in new construction. Muchnon-friable and encapsulated materials continued tobe used and still remain in place with little hazard.

Asbestos-cement, for example, was used in themanufacture of water pipe and roof and sidingproducts. The laws pertaining to the repair, re-moval and disposal of asbestos-cement and otherACM continue to change. Operation and Mainte-nance personnel are referred to Service manuals,regulations or other guidance on asbestos controland abatement and to publications of the Environ-mental Protection Agency, the Occupational Healthand Safety and Administration and applicable Stateand local agencies.


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4.5.4 Translucent Structural Panels 4.5.5.1 Maintenance. Painting is usually not re-Siding produced from combining polyester resins,fiberglass, and plastics may be encountered in somenew construction. As is the case with other flat andcorrugated sidings, it is important to keep fasteningdevices tight and replace broken panels.Replacement fasteners will be similar to those rec-ommended by the manufacturer of the product in-volved. It is obvious that siding material shouldmatch that existing in the building. Cleaning oftranslucent siding is paramount because it is usedfor lighting and decoration. Choice of detergentsand chemical cleaning solutions must be withinlimitations of the manufacturer's recommendations,or severe damage may result.4.5.5 Solid Vinyl SidingSolid vinyl siding is a pigmented polyvinychloridecompound, extruded into 0.035-inch-thick shapesand is available in both vertical and horizontalpatterns. The material is highly durable and avail-able with long-term guarantees for useful appear-ance life.

quired until after 20 years of installed life. Thesurface is easily cleaned with a mild detergent andwater.

4.5.5.2 Repair. Damage to the panels is not nor-mally anticipated, but should it occur the manu-facturer's recommendation for replacement shouldbe followed. This requires use of the manufacturer'sspecial tool to disengage the panel at the top or endof the panel where it overlaps a flashing. Disengagethe top of the damaged panel using the tool todisengage the locks. Remove the nails at the top ofthe damaged panel, and remove it. Install thereplacement by hooking it into the top lock of thepanel immediately below the repair and nail the topof the panel into place. Use the manufacturer's toolto lock the panel above the repair into the top lockof the replacement panel by slipping the tool acrossthe top of the replacement panel.

SECTION VI—EXTERIOR INSULATING SYSTEM

4.6.1 General b. Cut all components of the Dryvit systemA variety of exterior insulating systems have beenrecently developed and used in new construction oradded to existing structures. These systems employa layering of insulation board, reinforcing fabric,synthetic plaster, or copolymer adhesive andsynthetic plaster or copolymer finish. Most can beinstalled directly onto masonry, concrete, metal andwood frame structures. Most products arerelatively maintenance-free; however, they aresusceptible to damage. Repair and maintenance in-formation for two types of commercial products isas follows.4.6.2 Dryvit4.6.2.1 Maintenance. No routine maintenance isrequired. Under normal conditions there should notbe any cracking or peeling. The surface may bewashed with detergent or painted with an exteriorlatex paint if a color change is desired.

4.6.2.2 Repairs. Repairs should be attempted onlywhen the ambient temperature is above 40EF(4.5EC) and rising, and has been at least 40EF orabove for at least 24 hours. The manufacturer’srecommended repair procedure for heavily dam-aged areas is as follows:

a. Using a disk grinder, expose the smoothbase-coat Primus layer approximately 2 to 3 inchesall around damaged area. Use an aluminum oxidedisk of No.48 grit.

out of the damaged area. This includes the finishcoat, the base coat, the reinforcing fabric, and theinsulation board. Clean the exposed substrate ofany old Primus adhesive. Cut a piece of Dryvitinsulation board to fit neat and snug and rasp forprecise fit. Apply Dryvit mixed Primus adhesivefully over the back of the Dryvit insulation board toa thickness of about d inch.

c. Apply the Dryvit insulation board to thesubstrate. Cut Dryvit reinforcing fabric so that itwill cover patch area lapping on to exposed base-coat layer.

d. Apply Primus adhesive mix to the face ofthe insulation board. With a margin trowel, embedDryvit reinforcing fabric into the mixed Primusadhesive. The reinforcing fabric should be coveredwith Primus adhesive to produce a uniform base-coat surface.

e. Using masking tape, mask off the areaexposing approximately ¼ inch of the existingfinish. After approximately 24 hours, the finish coatcan be applied.

f. Trowel on a new finish coat over the newand existing base coat.

g. Allow the Dryvit finish to set up forapproximately 10 minutes, depending on weatherconditions. Remove tape from the wall.


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h. Feather edges of patch to blend inconspicu- e. Cut a piece of polystyrene to fit the openingously with texture of surrounding areas. After in the system. Make sure the fit is precise to avoidpatch has dried there will be a slight color variation any thermal breaks.between the patch and the surrounding area. Thisshould become less conspicuous in the time asenvironmental conditions blend the color of thepatch to the surrounding area. In order to be sure g. Apply adhesive to the back of theof proper color, Dryvit finish should be matched to polystyrene and put in place with firm pressurethe original batch number of the exiting Dryvit making sure the plug is adhered to the substrate.finish. Where the Dryvit insulation board is notheavily damaged, it does not have to be replaced.

4.6.3 Sto be placed.

4.6.3.1 Maintenance. No routine maintenance isrequired. The finish is permanent, colorfast, andscrubbable.

4.6.3.2 Repair. The manufacturer lists the follow-ing repair procedures for puncture, damaged cor-ners, and patching finishes. The minimum ambienttemperature is 38EF (3.4EC) for at least 12 hours.It is easier to repair a large area than a small one.Make patch large enough to work with.

a. Scrape off the Sto finish from the wallapproximately 2 inches around the damaged area.Be careful not to damage the ground coat and meshin this area.

b. Carefully cut the Sto reinforcing fiberglassmesh to approximately 1 inch from the outer pe-rimeter of the existing finish.

c. Remove the damaged area by cutting out aplug around the puncture leaving a strip of goodpolystyrene between the mesh and the damagedarea.

d. Scrape any remaining adhesive off the faceof the substrate.

f. Rasp plug to match thickness of existingpolystyrene if needed before applying to substrate.

h. Cut a piece of mesh to butt existing mesh.Apply reinforced plaster over area where mesh is to

i. Embed mesh in reinforced plaster, keepingsame thickness of existing ground coat. Allow rein-forced plaster to dry before applying finish.

j. After reinforced plaster has set, preparearea to receive finish. Using masking tape, coverexisting finish around patched area.

k. Apply finish and float out to match textureof wall.

l. Remove masking tape and use paintbrushto blend wet finish into the dry finish.

m. In repairing corners, the polystyrene mustbe replaced back far enough on the wall to allowproper adhesion of polystyrene used to replacedamaged area. Make sure corner is doublewrapped with Sto reinforced fiber mesh at least 2½inches.

n. To repair patching finish only, scrape offthe Ste finish approximately 1 inch around the dam-aged area. Using masking tape, cover existing finisharound patched area. Apply finish and float out tomatch texture of wall. Remove masking tape andusing a paintbrush, blend wet finish into dry finish.


5-1

CHAPTER 5

INTERIOR WALLS, PARTITIONS, AND CEILINGS

SECTION I—INTRODUCTION

5.1.1 General particularly wainscots, and areas subject to

This chapter considers the various types of interiorwalls, partitions and ceilings and describes methodsand procedures for their maintenance and repair. Inaddition to the requirements for strength, color,durability, and other qualities for constructionpurposes, properties directly affecting safety,acoustical characteristics and thermal insulationvalue of the finish material must be considered.

5.1.2 Types of Interior Walls and Partitions

Interior walls and partitions are usually constructedof wood studs, metal studs, blocks, or structuralclay tile with a plaster, gypsum board or ceramictile finish. Others are constructed of glazed struc-tural units, brick, block (painted or unpainted),metal, or glass.

5.1.3 Types of Ceilings

Ceilings are usually gypsum board, plaster, acous-tical tile, or metal, either applied directly to theunderside of the floor or roof framing or supportedby a suspended grid system.

5.1.4 Interior Finishes

5.1.4.1 Plaster. The various types of plaster aresimilar in composition and application but are de-signed for specialized uses.

a. Gypsum Plaster. Gypsum plaster is mostgenerally used in ordinary construction because itcan be readily applied to furred and lathed surfacesof exterior masonry and directly to interiormasonry. It can be applied over metal lath andgypsum products. High-grade, high-strengthgypsum plaster is generally limited to use inneuropsychiatric sections of hospitals. Gypsumplaster should conform to ASTM C-631 and C-28.

b. Lime Plaster. Lime plaster, found in manyolder buildings, is similar in application to gypsumplaster but should not be used in conjunction withgypsum products. Lime plaster should be repairedwith like material.

c. Keene's Cement Plaster. Keene's cementplaster produces a hard, moisture-resistancesurface, suitable for spaces given hard use,

continued moisture, such as baths, kitchens, andcertain hospital areas. Keene's cement plastershould be applied only over a gypsum plaster baseand should conform to Federal Specification SS-C-161A.

d. Portland Cement Plaster. Portland cementplaster may be applied directly to interior masonrywalls and over metal lath; it should never be appliedover gypsum products. It is recommended for usein plastering walls and ceilings of large, walk-inrefrigerators and other cold-storage spaces,basement spaces, toilets, showers, janitorial closets,and similar areas where Keen's cement plaster isnot economically justifiable.

e. Insulating Plaster. Insulating plaster differsfrom other plasters in that lightweight vermiculiteand perlite are used as an aggregate instead ofsand. It is lightweight, provides some thermal in-sulation, and gives a fire-retardant surface, to adegree determined by its composition and methodof application.

5.1.4.2 Tile. Ceramic tile, structural clay tile,glazed structural units, and similar water-resistantmaterials are commonly used for interior walls andwainscoting where moisture conditions andcleanliness are factors. Structural clay tile is usedprimarily for interior partitions and for backup forbrick walls. Tile finishes and wainscoting are usedin toilets, baths, kitchens, and certain hospitalspaces.

5.1.4.3. Wallboard. Gypsum wallboard shouldconform to ASTM C840 or C-36. It is composedof a gypsum core encased in a heavy manila-finished sheet on the face side, and a strong linerpaper on the back. Hard-pressed fiberboard may beused as wainscoting only when backed withnoncombustible material, such as gypsumwallboard. Structural-type fiberboard shouldconform to Federal Specification LLL-B-810.Where moisture resistance or extra strength isrequired, Class II or Class IV treated fiberboardshould be used; otherwise, Class I is satisfactory.Wallboard, in general, is used where conditions ofoccupancy do not subject it to severe services.


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5.1.4.4 Metal. Interior walls, partitions, or ceilings structurally separated wall increases soundof metal (steel, aluminum, etc.) are normally used transmission. For hollow walls not structurallyin industrial and office-type buildings and structures separated, such as ordinary wood-stud partitions,to withstand hard use or to contain hazardous a fill of noncombustible material between the studsoperations. Other common uses of metal include slightly improves the sound insulation.office partitions, toilet partitions, and sleepingcubicles.

materials are more easily cleaned and are more5.1.5 Functions and Characteristics

5.1.5.1 General. In the maintenance and repair ofbuildings and structures, care should be taken tomaintain the effectiveness of interior finishes as tofire resistance, insulation and acoustical functions.5.1.5.2 Fire Resistance. Conventional wall con-struction materials, such as gypsum block surfacedwith plaster of the required thickness, brick, con-crete, hollow tile, and concrete block, are consid-ered nonhazardous and noncombustible. Partitionsor ceilings constructed of assemblies of wood ormetal studs or joists, or of metal, gypsum, or woodlath, surfaced with cement, lime, or vermiculiteplaster, are considered nonhazardous. A sheet-metal covering applied directly to wood joists orover old plaster ceilings, although superior tohighly combustible materials, offers little resistanceto fire and increases the effort required to ex-tinguish fires in concealed spaces, such as betweenjoists.5.1.5.3 Insulation. Noncombustible materials usedfor insulation of buildings and structures againstheat or cold, such as mineral or glass wool, have asecondary effect of increasing fire resistance, if theystay in place and do not settle to create voids. Rigidinsulating boards of polyurethane and perlite arealso used on walls.5.1.5.4 Noise Control.

a. Sound Absorption. Acoustical materialsapplied on walls, partitions, and ceilings absorbnoise and aid hearing by reducing echoes andreverberation. Porous or low-density materials,similar to those used for thermal insulation, arecommonly applied in theaters, auditoriums, andother areas where good acoustics are required. Thematerials should be noncombustible or fire-resistant, such as mineral and glass wool andlaminated gypsum wallboard attached to theframing with resilient clips.

b. Exterior Sound. Insulation from exteriornoise is sometimes part of the interior sound-absorption problem. The best resistance to noisepenetration usually can be obtained with heavyrigid walls and floors, or multiple-layerconstruction separated by airspaces. Suchconstruction keeps out sound by preventing thevibration of wall or floor. Any mechanicalconnection across the intervening airspace in a

5.1.5.5 Cleanability. In general, ceramic tile, glass,glazed-faced masonry, and similar hard-surfaced

resistant to moisture and staining than plaster,wood, and metal.

5.1.6 Accessory Materials

5.1.6.1 Lath. Metal lath should conform to FederalSpecification QQ-L-1O1. It may be expandedmetal, woven wire mesh, or woven wire fabric,with a paper or other backing. Gypsum lath or rocklath, conforming to Federal Specification SS-L-30D, is available in solid, perforated, and insulatingtypes. Expanded metal lath should be used toreplace wood lath in all rehabilitation work. Itshould be placed with the long side of the sheetperpendicular to the supports, and then be nailed orstapled to wood supports and wired to metalsupports. In hanging laths for ceilings, the jointsshould be broken so alternate sheets run through,to avoid plaster cracks. When gypsum lath is used,all joints should be staggered so that joints do notmeet on the same stud or at the ceiling line.

5.1.6.2 Furring. Furring consisting of wood ormetal strips serves as a framework for lath; it maybe used to level uneven wood partitions or ceilingframing or masonry wall surfaces, or to provide adead airspace in walls for insulation.

5.1.7 Plastering Accessories

To obtain a satisfactory plaster surface, a numberof accessories are required.5.1.7.1. Grounds. Grounds are wood strips of uni-form thickness installed around all openings, at thebottom of walls near the floor, at the top ofwainscots, at chair-rail heights, and other placeswhere trim is required. They serve as a guide inbringing the plaster to a uniform thickness for aneven surface, form a stop against which the plasteris finished, and furnish means for fastening theinterior trim to the walls. Temporary wood groundsare often used in gauging the thickness of thescratch and brown coats of plaster.5.1.7.2 Base Screeds. Base screeds, like plastergrounds, serve as a guide to gauge the plasterthickness and as plaster stops. Screeds are used atthe bottom of plaster walls where the plaster joinsthe floor base, or where it joins the wainscot inwalls with tile or other similar materials used asbases or wainscots.


5-3

5.1.7.3 Corner Beads. Corner beads should be in- the plaster. Corner laths may be procured installed at all external plaster corners. They serve a preformed strips or be cut from metal lath sheetdual purpose: as a plaster stop gauge for acquiring and formed on the job to fit the particular cornersa uniform surface finish, and as a reinforcement to in which they are to be installed. Corner lathsstrengthen plaster corners to prevent them from should be fastened at the edges, with staples usedbeing broken off. Corner beads are manufactured in over wood and lath and wire over metal lath.two all-metal styles: the bullnose bead, which is a Corner laths should not be fastened by nailingwide-radius bead and is designed especially for through into the framing because stresses in thecorners receiving unduly hard use; and the standard structure will then be transmitted directly into thebead, which has a very small radius and is designed plaster, causing a crack.to provide sharp, clean corners. A corner beadsuitable for installation on plasterboard (dry wall)corners is a fabricated product consisting of a ¾-inch hard metal strip, formed to a right angle andglued under pressure to a 2-inch strip of fabric ortough, treated paper. Specially constructed beadsare available for forming arches and other irregularcorners.

5.1.7.4 Corner Lath. The corner lath is an angle- 12- by 24-inch strip of metal lath fastened over theshaped strip of lath with 2- or 3-inch legs, usually plaster base at an angle in relation to the opening ofinstalled at an interior vertical or horizontal plaster approximately 45E. Such additional reinforcing iscorner as a reinforcement to prevent cracking of not required over metal lath.

5.1.7.5 Strip Lath. A strip lath, as the term indi-cates, is a strip of metal lath, 4 or more incheswide, intended for application over joints of dis-similar plaster-base materials where the surfaces tobe plastered lie in the same plane and cannot beeffectively bonded or tied together without the helpof metal lath strips. Each corner of a door, window,or other opening in a plastered surface will have a

SECTION II—REPAIR AND MAINTENANCE OF PLASTER AND TILE

5.2.1 Application of Plaster insulation value and to materials with fireproofing

5.2.1.1 Preparation. Before plastering is started,the plaster base, whether masonry or lath, and thegrounds should be inspected. The existence and lo-cation of plumbing, heating, and electrical outletsshould be checked.

5.2.1.2 Bond. A secure bond between plaster andbase is necessary to develop strength and resistanceto damage in walls and ceilings. A "mechanical"bond is formed when plaster is pressed through themesh of metal lath or the holes of perforated boardlath, forming keys on the other side. A "suction"bond is formed when plaster is applied overnonperforated gypsum or insulation board lath andover a masonry base. In suction bonding, the small,needlelike plaster crystals penetrate the surfacepores of the base by suction; when the plaster sets,the base and plaster become "welded" together.When perforated board lath is used, bothmechanical and suction bonds are developed.

5.2.1.3 Plaster System. Plaster is applied in a seriesof coats called scratch, brown, and finish.Application and mixes vary to meet conditions im-posed by original construction on which the plasteris applied and by the area of use. Three-coat workis generally advisable over metal lath while two-coat work often suffices over masonry and gypsumlath and gypsum partition tile. Consideration willalways be given to the use of light plasteraggregate, such as perlite and vermiculite, for

characteristics, such as gypsum board, metal lathand other components, for wall surfaces underrepair. Proper drying and settling of one coatbefore another coat is applied is necessary for goodplastering. Adequate ventilation is required forgood drying. If the entire building is enclosed andheated, fans may be used to eliminate dead air-spaces and facilitate drying.

a. Scratch Coat. The scratch coat consists ofa mixture of sand or lightweight aggregate andplaster. The sand or aggregate is increased for ascratch coat over masonry. Sufficient material andpressure must be applied to form full keys on metallath or a good bond on masonry. The scratch coatis left with a rough surface to accept the next coat.

b. Brown Coat. The brown coat is similar tothe scratch coat except that sand or aggregatecontent is increased. It is applied after the scratchcoat has set firm and hard. The brown coat is laidflush to the grounds, straightened to form a truesurface and left rough.

c. Finish Coat Float or sand finish is achievedby using a rubber or carpet float. The float finish ofgypsum vermiculite should be placed only on basecoats of gypsum lightweight aggregates. Rec-ommended proportions for this finish coat are 1part gypsum gauging plaster, 5 parts lime putty, ato b part fine, white sand or lightweight aggregatefines.


5-4

5.2.2 Causes and Signs of Plaster Damage filling hairline shrinkage cracks is to mix spackling

Cracks, holes and looseness in plastered surfacesare signs of excessive internal or external stresses.They may be caused by poor workmanship, such asimproper proportions or application of the plaster,imperfect lathing, and poor atmospheric conditionsduring plastering; or by moisture infiltration or anexcess of moist air generated inside a buildingframe. External stresses that cause plaster damage 5.2.5.1 Structural Cracks. Structural cracks areshould be investigated and corrected before repairs easily identified because they are usually large andare made to the plastered surfaces themselves. well defined, extending across the surface and

5.2.3 Plastering Equipment

Equipment for making minor repairs consists of aspatula or putty knife, a small diamond-shapedpointing trowel, a sharp chisel, a linoleum knife, ahammer, and a shallow mixing pan.

5.2.4 Patching

5.2.4.1 Structural Cracks. Generally, two coats ofpatching material are required to repair widestructural cracks.

a. The first coat may be a job mix composedof 1 part fibered gypsum plaster and 2½ partsplastering sand, by volume, mixed with clean waterto a uniform color and workable consistency.

b. Material for the second coat may be eithera neat gypsum plaster or a mix of 1 part hydratedlime and ½ part calcined gypsum mixed with waterto a suitable consistency.

c. A small amount of casein glue added to theabove mix insures easier application because ittends to retard the setting time of the mix. Theaddition of glue also prevents shrinking of the mixand helps form a better bond with the old plaster.

d. In lieu of the mixes described in (a) and (b)above, a commercial patching plaster may be used.This material, known as spackling compound, is amixture of plaster of Paris and powdered glue,which is mixed with clean water to the consistencyof soft putty.

e. The quantity of any patching material mustnot exceed that which can be applied within 30minutes after mixing. Plaster material should not beretempered (by adding water) once it has begun todry out and harden. Retempered plaster placed onthe wall will dry and become soft and crumbly.

5.2.4.2 Map Cracks. Best patching results in therepair of medium-width map cracks are usuallyobtained by use of the spackling compounddescribed in (d) above.

5.2.4.3 Hairline Shrinkage Cracks. One method of

compound to a thin paste and scrub it into thecracks.

5.2.5 Repair of Gypsum and Lime Plaster

Identification of failures in gypsum and lime plastersurfaces, possible causes, failure and methods ofrepair are discussed below.

entirely through the plaster. They generally developduring the first year after completion of con-struction and, in most cases, can be successfullyand permanently repaired. However, before repairsare initiated, the cause of the failure should bedetermined from an engineering standpoint andnecessary precautions taken to prevent recurrenceof the failure. Structural cracks may extend diago-nally from the corners of door and window open-ings, run vertically in corners where walls join, runhorizontally along the junction of walls andceilings, or occur in walls where two unlike mate-rials join.

a. Causes. Structural cracks may be caused byone or more structural defects, such as foundationsettlement; failure of masonry wall section byshrinkage or cracking; sagging, warping, or shrink-age of wood frame members; insufficient bracing ofwood frame members, or use of undersized or im-properly spaced wood frame members.

b. Repair. To repair a structural crack, use alinoleum knife or chisel to cut out and removeloose material. The crack must be formed to a V-shape to provide adequate keying action by makingthe surface opening narrower than the bottom ofthe crack. Care should be exercised to widen thecrack only enough to insure a good bond betweenpatching plaster, old plaster, and lath. Expandedmetal or wire lath should be cleaned and the meshopened so that, when patching plaster is forced intothe opening, a good key is formed. Break out thekey between wood lath so that a new key can beformed when patching material is forced into place.Thoroughly wet wood lath before applyingpatching plaster. Brush out all loose material,remove all grease or dirt from surrounding surfaceareas, and wet the edges of the groove. Press thefirst coat of patching plaster firmly into place, fill-ing the groove nearly to the surface; allow it to setuntil nearly dry but not hard; then complete thepatch by applying a coat of finish plaster, strike offflush, and trowel smooth. If the edges of the oldplaster and the wood lath are not thoroughlywetted, they serve as a wick to draw the water


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from the fresh plaster, causing it to dry out, remain falling, held together only by the hair or fiber in thechalky, and crack around the edges of the patch. In base coat. Occasionally moisture causes theapplying the plaster, special attention should be fastenings holding the lath to the structural frame togiven to the edges of the patch to insure a firm, corrode, permitting both the lath and plaster tosolid bond between old and new plaster. bulge or sag. Another cause of bulging plaster is5.2.5.2 Map Cracks.

a. Map cracks are less noticeable thanstructural cracks. They penetrate through theplaster but do not extend entirely across the surfaceand generally occur as a series of irregular cracksrunning at various angles, embracing areas 6 inchesor more in width and up to several feet in length.Map cracks are generally caused by improperbonding between the plaster and lath or masonrybase and indicate inferior workmanship, the use ofpoor quality materials, or a combination of the two.

b. Repair. Normally map cracks are repairedin much the same manner as described forshrinkage cracks. Where large areas are badlycracked, the repair method for loose plaster,described in paragraph 5.2.5.4a, may be used.5.2.5.3. Shrinkage Cracks.

a. Shrinkage cracks are sometimes referred toas crazing and resemble map cracks in appearancebut are ordinarily confined to the finish coat. Theydo not extend entirely through the plaster surface,and cover a much smaller portion of the wall orceiling surface. Shrinkage cracks generally resultfrom careless workmanship, too rapid drying of thesurface, insufficient troweling, troweling while thesurface is still too wet, or by not troweling until thesurface had become too dry.

b. Repair. Normally shrinkage cracks are re-paired by filling with spackling compound. Whereshrinkage cracks penetrate the base course and areof such extent that they will not retain such a paintmixture, they should be cut out and repaired in thesame manner as described for structural cracks.5.2.5.4 Holes. Holes are repaired in the samemanner as structural cracks. Cutting out the looseplaster surrounding the hole requires extreme carenot to loosen an unnecessary amount of soundplaster.

a. Loose Plaster. Loose plaster is indicated bybulging and cracking of large areas of the plastersurface. The extent of loosened plaster can be de-termined by lightly tapping the surface with a smallhammer, with the resulting sounds indicating theextent of the loose area. Loose plaster may resultfrom excessive moisture caused by leaks in theroof, seepage through an exterior wall, plumbingleaks, or heavy condensation. This excessivemoisture causes the plaster to loosen. In somecases, the plaster may bulge or sag but continue tohang in this condition quite a long time before

the use of incompletely hydrated lime in the plastermix. In localities where high humidity is prevalent,moisture causes a continued hydration of the lime,which weakens the plaster and destroys the bondbetween plaster and base. This condition usuallyoccurs in the spring and summer months, startingfrom the first to third year after plastering andcontinuing indefinitely.

b. Repair. Before repairing the damagedplaster, it is necessary to locate and eliminate thesource of moisture. To prevent loose plaster fromfalling until permanent repair can be accomplished,temporary repair may be made by securing theloose plaster with a section of wallboard nailedsecurely to the wall or ceiling over the areaaffected. Nails should be of sufficient length topenetrate through the plaster and obtain a firmbearing in the studs or joists. Repairs of apermanent nature should be made as soon aspracticable. Remove all loose plaster around thebreak, working back in the surrounding area to apoint where solid plaster (well keyed to the lath,which, in turn, is solidly secured to the structuralframes) is reached. Remove defective lath andreplace with suitable plaster backing, such as metallath or plasterboard, and securely refasten all laththat has become loosened.5.2.5.6 Old Plaster Surfaces. Old, worn,crumbling plaster is repaired in the same manner asloose plaster. However, in the attempt to repair oldplastered surfaces, the operation of removing theaffected areas sometimes causes areas of apparentlysound plaster to fall. This is evidence that the entireplaster surface has deteriorated to the extent thatreplastering of the whole area is necessary.

5.2.6 Repair of Keene's Cement Plaster

Keene's cement plaster is much harder and lesssusceptible to damage from moisture than gypsumand lime plasters and therefore requires much lessmaintenance and repair. Keene's cement plaster isnormally used in areas subject to excessive mois-ture conditions, such as showers, toilets, baths, gal-leys, laundries, machinery and equipment rooms,and similar spaces. When repairs of Keene's cementplaster surfaces are necessary, the same principlesdescribed above for repair of gypsum plaster apply,with the exception that Keene's cement plastershould be used, in accordance with manufacturer'sinstructions, instead of patching plaster and gypsumplaster.


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5.2.7 Repair of Portland Cement Plaster

Surfaces subjected to hard use or exposed to mois-ture, such as walls and ceilings of large walk-in re-frigerators and cold storage spaces, exterior sur-faces such as undersides of canopies and marquees,and other locations where, for economical reasons,Keene's cement plaster is not justifiable, are oftencoated with portland cement plaster. The types offailures and methods of repairing portland cementplaster are basically the same as described abovefor gypsum plaster. In patching small areas, theedges of the surface surrounding the defective areamust be thoroughly and continuously wetted for atleast 1 hour before application of the patching ma-terial. Just prior to applying the patch, dust theentire edge of the exposed plaster with a light coatof portland cement. Press the first coat of portlandcement plaster, composed of 1 part portlandcement, 3 parts plastering sand, and ¼ part limeputty, firmly into the groove or hole nearly to thesurface, using particular care to insure that no voidsare left around the perimeter of the patch. Scratchor roughen the surface of the patch with a wirebrush or nail to make a base for receiving the finishcoat. Thoroughly cure the patch by keeping it moistfor at least 72 hours; then let it dry thoroughly, fornot less than 7 days, prior to applying finish coat.Just prior to applying of the finish coat, moisten thepatch thoroughly and firmly press the plaster intothe remaining cavity, float to a smooth, evensurface, and then trowel to the same texture as thesurrounding surface. Keep the patch moist for atleast 3 days.

5.2.8 Material Handling Precautions

All material in bags or bundles should be stacked,blocked, interlocked, and limited in height so thatthe pile is stable and secure against sliding or col-lapse. Judgment must be used in stacking andstoring materials in any structure. Concentratedloads of stored materials can exceed the allowableuniform live load by 100 percent, if the loads arestacked adjacent to outside walls or over beam andcolumn supports. Never stack materials in thecenter of joist spans. When material is placed in orencroaches on passageways, it should be located topresent the least possible hazard. Limits of allow-able loads will be determined through consultationwith structural personnel of the installation engi-neer organization.

5.2.8.1 Cement and Lime.

a. Bags of cement and lime should not bestacked more than 10 bags high without stepback,except when restrained by walls of appropriatestrength.

b. The bags around the outside of the stackshould be placed with the mouths of the bags facingthe center of the stack.

c. During unstacking, the entire top of thestack should be kept nearly level and the necessarystep-backs maintained.

d. Handle cement and lime in paper bags withcare to prevent bags from breaking.

e. Store lime and cement on off-the-floor plat-forms in dry spaces. Lime must be kept dry instorage to prevent possible premature slaking,which could cause fire.5.2.8.2 Personal Protective Measures. Workmenwill observe the following precautions:

a. Wear heavy gloves when handling metallath.

b. Wear goggles for eye protection when han-dling cement and lime.

c. Wear shirts with closed neck andwristbands and insure that exposed parts of thebody do not come in direct contact with lime.

d. Avoid wearing clothing that has becomestiff and hard with cement or lime; such clothingirritates the skin and may cause infection.

e. Personal cleanliness and frequent washingare effective preventives of skin ailments.5.2.9 Replacement Application of Ceramic Tile

5.2.9.1 Scratch Coat. A scratch coat for applica-tion as a foundation coat must be not less than ¼inch thick and composed of 1 part cement to 3parts sand, with the addition of 10-percent hydrat-ed lime by volume of the cement used. While stillplastic, the scratch coat is deeply scored orscratched and cross-scratched. The scratch coatshould be protected and kept reasonably moistduring the seasoning period. All mortar for scratchand float coats must be used within 1 hour aftermixing. The retempering of partially hardenedmortar should not be permitted. The scratch coatmust be applied not more than 48 hours, nor lessthan 24 hours, before starting the setting of title.5.2.9.2 Float Coat. The float coat should be com-posed of 1 part cement, 1 part hydrated lime, and3½ parts sand. It must be brought flush withscreeds or temporary guide strips, well placed togive a true and even surface at the proper distancefrom the finished face of the tile.5.2.9.3. Setting Wall Tile. Wall tile should bethoroughly soaked in clean water before it is set. Itis set by neatly troweling a skim coat of portlandcement mortar on the float coat, or applying a skimcoat to the back of each tile unit, and immediatelyfloating the tile into place. Joints must be straight,


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level, perpendicular, and of even width not of the back of each tile.exceeding / inch. Wainscots are built of full1

16courses, which may extend to a greater height, butin no case more than 1½ inches lower than thespecified or figured height. Vertical joints must bemaintained plumb for the entire height of the tilework.

5.2.9.4 Grouting. All joints in wall tile should be Tile should not be shoved into place. Joints must begrouted full with a plastic mix of neat white cement cleaned of any excess adhesive to provide for aimmediately after a suitable area of tile has been satisfactory grouting job. When the butteringset. The joints should be tooled slightly concave method is used, tile is pressed firmly into placed,and the excess mortar cut off and wiped from the using a "squeegee" motion to spread the daubs offace of tile. Any interstices or depressions in the adhesive. After the adhesive partially sets, before itmortar joints after the grout has been cleaned from is completely dry, all tiles must be realigned so thatthe surface should be roughened at once and filled faces are in same place and joints are of properto the line of the cushion edge before the mortar. width, with vertical joints plumb and horizontalAll joints between wall tile and plumbing or other joints level.built-in fixtures should be made with a lightcoloredcaulking compound. Immediately after the grouthas had its initial set, tiled wall surfaces should begiven a protective coat of noncorrosive soap orother approved protection.

5.2.10 Application of Tile in Existing Construc-tion

Wall tiles installed over existing and patched ornew plaster surfaces in an existing building arecompleted as described in paragraph 5.2.9, exceptthat such wall tiles are applied by the adhesivemethod.

5.2.10.1 Priming. Where wall tile is to be installedin areas subject to intermittent or continual wetting,the wall areas should be primed as recommendedby the manufacturer of the adhesive used.

5.2.10.2 Adhesive Application. Wall tile may beinstalled either by the floating method or by thebuttering method. In the floating method apply theadhesive uniformly over the prepared wall surface,using quantities recommended by the adhesivemanufacturer. Use a notched trowel held at theproper angle to insure a uniformly spread coatingof the proper thickness. Touch up thin or barespots by an additional coating of adhesive. The areacoated at one time should not be any larger thanthat recommended by the manufacturer of theadhesive. In the buttering method, daub theadhesive on the back of each tile in such amountthat the adhesive, when compressed, will form acoating not less than / inch thick over 60 percent1

16

5.2.10.3 Setting Tile. Joints must be straight, level,plumb, and of even width, not exceeding / inch.1

16When the floating method is used, one edge of thetile is pressed firmly into the wet adhesive, the tilesnapped into place in a manner to force out all air,then aligned by using a slight twisting movement.

5.2.10.4 Wainscots. Wainscots are built of fullcourses to a uniform height. The wainscot heightmay be adjusted somewhat to accommodate fullcourses, but the adjustment should not exceed 11/2inches from the norm.

5.2.10.5 Grouting The adhesive should be allowedto set for 24 hours before grouting is done. Jointsmust be cleaned of dust, dirt, and excessive adhe-sive, and should be thoroughly soaked with cleanwater before grouting. A grout consisting of port-land cement, lime, and sand, or an approved ready-mix grout may be used, but the grout must bewater resistant and nonstaining.

5.2.10.6 Caulking Nonstaining caulking com-pound should be used at all joints between built-infixtures and tile work, and at the top of ceramic tilebases, to insure complete waterproofing. Internalcorners should be caulked before corner bead isapplied.5.2.11 Repair of Ceramic Tile

Cracked and broken tile should be replacedpromptly to protect the edges of adjacent tile andto maintain waterproofing and appearance. Timelypointing of displaced joint material and spalledareas in joints is necessary to keep tiles in place.5.2.12 Cleaning

Newly tiled surfaces should be cleaned to removejob marks and dirt. Cleaning should be done ac-cording to the tile manufacturer's recommendationsto avoid damage to the glazed surfaces.

SECTION III—REPAIR AND MAINTENANCE OF DRY-WALL CONSTRUCTION

5.3.1. General sheet materials and wood products are also used to

Dry-wall construction usually consists of a gypsumwallboard finish. However, other manufactured

provide interior wall construction other than wetplaster. When the following items are used, the


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item used should be in conformance with the Fed- 5.3.2 Single-Thickness Gypsum Wallboarderal Specification or Standard cited: gypsum board(AA-L-30); hardboard (LLL-B-810); particle board(ASTM C-208); plywood (Product Standard PS-1-66 or Commercial Standard CS-35-61); acousticalunit prefabricated (SS-S-118A). This chapter dealswith the maintenance and repair of these types ofdry-wall construction.

5.3.1.1 Repair.

a. Fixed- Wall Construction. Maintenance andrepair of interior wall boarding generally requiresthat nails, screws, and other fasteners be kept in asecure condition. Cracks in plaster-type boards maybe repaired in a manner similar to plaster repair.Joints which fail in dry-wall construction must berecemented and taped. Broken panels usually arebest repaired by replacement of a complete panel.When repairs are completed, finish to match theadjoining area. All fastening, such as nailing,screwing, or gluing, must be at least equal to the"as built" construction.

b. Nonload-Bearing Partitions. Nonloadbearing partitions carry no load other than theirown weight and are used under floors or roofs thatare trussed or framed with beams and girders tocarry the superimposed load to the structuralframe. Nonload bearing partitions can be lesssubstantial than load-bearing partitions and areusually placed after structural frame, roof, andfloors are in place. Periodic inspection of thesepartitions will be made for marks, dents, scratches,cracks and other surface damage. These nonload-bearing partitions can be repaired, strengthened,plumbed, and aligned without regard to thestructural frame or ceilings and may be removed toprovide other interior arrangements of space.

c. Trim and Wainscot. Trim and wainscotmaterial will vary to suit design requirements fordifferent interiors. Wood trim and wainscot must bekept nailed, screwed or otherwise secured. Whenbroken areas occur, they should be repaired orreplaced with like material and fastening devices.Ceramic tile may occasionally be patched withplaster or plastic materials, but it is usually moresuitable to extract the broken piece and replace itwith a new one. Joints should be kept in goodrepair, and new joining material placed wheresevere spalling occurs. Synthetic moldings must bekept securely fastened to the wall so moisture anddirt do not collect between them and the wall.Mastic of the type used in the original constructionshould be used for repair or replacement ofmoldings and wainscots of this type.

5.3.2.1 Nailing. Secure gypsum wallboard tosupports with 1d inch by 0.101-inch, blued,helically threaded, tapered screwnail with mediumdiamond point. Space nails not less than % inchfrom edges, 5 to 7 inches apart on ceilings, and 6 to8 inches apart on walls. Drive nails with headsslightly below the surface, but do not use a nail set.

5.3.2.2 Finish Joints. Square-edge sheets are rec-ommended for temporary construction. Sheets with½- to / -inch bevel on the long edges are used3

16where the joint is featured. The recessed-edge sheetis used where a concealed reinforced joint isdesired. Finish of recessed joint consists of fillingthe recess with cement, into which a perforatedtape is imbedded. A thin covering coat of cement isapplied over the tape. Second and third coats ofcement are applied after preceding coats are dry.When the last coat of cement is dry, the jointshould be sandpapered smooth and level with therest of the wall.

5.3.2.3. Gypsum Backing For backing glazed orother wallboard linings and wainscots, use gypsumplasterboard, conforming to Federal SpecificationSS-L-30. Install boards horizontally with jointsstaggered. Secure to supports with 13-gage, bluedor cement-coated, 1 / -inch flathead nails, spaced5

16about 4 inches apart on all bearings.

5.3.2.4 Limitations. Maximum spacing of bearingsshould not exceed 24 inches. Gypsum board shouldnot be installed in damp places such as showers andbathrooms. Do not use gypsum board as a base forattaching tile or other materials with adhesives.

5.3.3 Double-Thickness Gypsum Wallboard

5.3.3.1 Planning A double thickness of gypsumwallboard is produced on the job by laminating twothicknesses of d-inch gypsum wallboard, using aspecial adhesive to bond the layers. The resultingwalls are strong, can stand heavy abuse, and arevery resistant to cracking and sound transmission.On walls not more than 8 feet 3 inches in height,the first layer is applied vertically, with edgescentered on and nailed to studs. The second layerof wallboard is then applied horizontally across thestuds. Where the ceiling is between 8 feet and 8feet 3 inches, the gap is filled in with scrap stripsand concealed by the baseboard. Where walllengths exceed 12 feet, vertical end joints arestaggered to fall between, not on, framingmembers. Use wood cleats on the face of the boardto hold the ends in place until the adhesive has set,and then remove them. Use 12-foot panels,wherever practical, to minimize end joints. Where


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walls exceed 8 feet 3 inches in height, it is more 5.3.3.4 Spreader Blade. A metal cement spreaderpractical to apply the first layer of wallboard hori- blade is recommended. With blades made of otherzontally, breaking all end joints between studs, materials, the cement tends to accumulate in thewhere 12-foot boards will not span the wall length. notches and dry, preventing proper spreadingThe face layer is then applied vertically, with full- action. Stainless steel or galvanized steel make thelength boards extending from floor to ceiling, best spreaders. The spreader should have the ap-eliminating all the joints. Where joints in the first proximate stiffness of a plaster trowel blade. Theand second layers are parallel, they should be offset blade should be kept reasonably clean at all times.at least 10 inches. Edges of the face layer should A 10-inch blade is most effective for spreading thebe centered on and temporarily nailed to the cement.studs.

5.3.3.2 Application. Make a thorough inspectionof the framing before applying the first layer ofwallboard. Studs and joists should be in true align-ment. Soil pipes, bridging, fire stops, etc., must notprotrude beyond framing members. To insureproper application of the second or face layer ofwallboard, a definite plan for erection should beformed before the first layer of the board is applied.Ceiling height will determine whether the base layeris vertical or horizontal. Apply the base layer with1d-inch by 0.101-inch blued, helically threaded, 5.3.6 Hard-Pressed Fiberboardtapered screwnails with medium diamond pointspaced 8 inches on centers. Cut the face layerpanels to correct size. Prepare the laminatingadhesive cement in accordance with the wallboardmanufacturer's recommendations. Using a notchedspreader blade, spread the mixed cement uniformlyover the entire back surface to the extreme edgesof the board. After the board is in place, wipe awayany cement forced out along the edges. When theface layer is applied horizontally, apply the firstsheet to the upper wall. With temporary nailing,secure the board in place until the cement has set.Secure long edges by nailing wherever they occuron or across framing members. On walls, spacenails in the center of the board 16 to 24 inches oncenters. Following application of the upper panels,place the lower face panels. Butt the top and lowerpanels closely together.

5.3.3.3 Finishing Nail Holes and Joints. All tem-porary nails should be countersunk at least d inchwith / -inch nail set. This is done after the face5

32layer has been in place long enough for the cement Glazed wallboard suitable for wainscots consists ofto dry. Cement dries in 24 hours, but under adverse a base material with a factory-applied finish. It mayconditions, allow 48 hours. Fill nail holes with a only be used when backed by noncombustiblejoint cement mixed to a puttylike consistency. For material. The base may be made of asbestos fibertapered joints, spot nail holes with joint cement and and cement formed under pressure into dense,then finish as normal tape-reinforced, recessed monolithic sheets, a structural-type fiberboard, orjoints. Butt or square-end joints are treated the a hard-pressed gypsum sheetrock. Finish on ex-same as tapered-edge joints. However, finishing posed face is a factory-applied gloss coating. A va-coats of joint cement are feathered wider riety of colors are available, such as white, ivory,(approximately 24 inches) because there is no taper yellow, peach, green, blue, red, and black. In addi-in which to embed the tape. tion to these colors, other finishes give the appear-

5.3.4 Cement-Asbestos Wallboard

Cement-asbestos board is no longer used.

5.3.5 Insulation Board

Make all joints between boards over solid bearingsand bring edges of board into moderate contact,but do not spring into place. Nail boards with 1½-inch, blued plasterboard nails spaced 6 inches oncenters along edge bearings and approximately 12inches on centers at intermediate bearings.

This type material may only be used as wainscotingwhen backed with noncombustible material, such asgypsum wallboard. When a structural-typefiberboard is required, use / -inch material con-5

16forming to Federal Specification LLL-B-810.Where moisture resistance or extra strength is re-quired, install Type II fiberboard; otherwise, Type1 is suitable. Installation is similar to that describedpreviously for insulation board. Make certain thatmaterial is preexpanded before installing Type IIfiberboard in areas subject to moisture or steam, orin very humid localities. To do this, scrub thefiberboard on the screen side with a stiff broom andcold water until it turns a very dark brown(chocolate), or a decided black in the case of theblack-treated board. Following this, stack thewetted boards face to face and wetted back toback, and allow them to remain in this positionovernight or preferably for 36 hours.

5.3.7 Glazed Wallboard

ance of several woods, such as walnut, mahogany,


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knotty pine, oak, and red gum. Most boards are 5.3.9 Furring in Wallsmade in 4-foot widths and lengths of 4 to 12 feet.Thickness range fromc to d inch. The d-inch-thick boards can be applied by nailing over furringstrips, in which case make all joints over solidbearings and secure with 1¼ inch, 18-gage brads,driven ¼ inch from edges on 4- to 6-inch spacingsand about 12-inch spacings through the body of theboard. An alternate method of installation consistsof spreading an adhesive over a smooth, solidbacking of noncombustile material such as gypsumwallboard. Cut and fit glazed boards to a close fit.Lay the board on the adhesive-coated wall or ceil-ing and push firmly into place. Do not spring intoplace. Clean off any excess adhesive that mayappear at joints, using cleaner recommended by theboard manufacturer for that purpose. Immediatelyafter setting the board in position, insure solidcontact with backing by placing previouslyprepared braces. Leave the braces in place until theadhesive sets, usually overnight. For someapplications, brads may be used to support theboards while the adhesive sets. The nails may beeither countersunk or withdrawn and the holesfilled with material matching the board finish. Paneleffect, if desired, is obtained by installation ofmoldings over board joints and around openings.These moldings are available in a variety of sizes,colors, and materials, such as wood, plastic, metalalloys, and stainless steel.

5.3.8 Plywood Linings

Plywood acceptable for interior wall and ceilinglinings will be equal to or better than three-plysoftwood plywood, interior grade, not less than ¼inch thick, manufactured in accordance with therequirement of Product Standards PS 1-66. It maybe used when backed with noncombustile materials.Face veneer may be Douglas fir or other softwoodor hardwood with smooth surface suitable forpainting or staining. The economical proceduregenerally calls for the installation of the larger sizesheets. Before starting the installation, see thatstud, furring and ceiling joist spacings do notexceed 24 inches on centers. Make all joints,including end joints, over solid bearings. Fit panelsclose but do not force into place. Secure with six-penny nails spaced 6 inches on centers on interme-diate bearings. Plywood for wainscots is usually setwith the grain running horizontally. Plywood forwall lining is set with the grain running vertically.Grain of plywood on ceiling should be parallel withthe long dimension of the room.

5.3.9.1 Placing When applying interior surfacingmaterials, install furring strips vertically, spaced notmore than 2 feet on centers. It is also advantageousto place other furring strips so that each sheet ofsurfacing material is supported horizontally atdistances of about 4 feet on centers. Wood furringstrips supporting metals lath and plaster are spaced16 inches on centers. Furring strips are alsoinstalled around all openings or wherever properinstallation of wall, partition, or ceiling liningrequires their use.

5.3.9.2 Fastening Furring strips may be secured tomasonry walls by the methods given below.

a. Cut or case-hardened nails placed on 2-footcenters provide a simple and satisfactory way tofasten furring strips to walls or ceilings. The wedg-ing action of a cut nail gives additional holdingpower. Furring strips are leveled or plumbed byinserting wooden wedges under the nailing point.

b. The same procedures used for nailing areused for bolting. Toggle bolts or butterfly bolts canbe used to attach furring strips to hollow-coremasonry material. The use of bolts requires drillinga hole in both the strip and the masonry. Thismethod is slower than nailing and should be usedonly when the superior holding power of a bolt isrequired.

c. Powder-Actuated Tools. The developmentof powder-actuated tools has provided a means offastening any construction material to steel or con-crete with great speed and ease. A wide variety ofpins and studs are available to suit the needs of thejob at hand. The pins are placed in the tool, similarto a handgun, and fired into place by a specialpowder charge. These tools can be used to fastenfurring strips to masonry, as well as for a variety ofother uses. The tool requires a trained operator andobservation of prescribed safety procedures.

5.3.10 Furring in Ceilings

5.3.10.1 General. Ceilings are furred to obtainstraight surfaces and to correct any difference inlevel on the underside of the joist. Furring strips,spaced 12 to 16 inches on centers, are run perpen-dicular to the underside of the floor or ceiling joistsand secured with 10-d nails. These strips arebrought to even surface by working from leveledfurring strips extending around the perimeter of theceiling.

5.3.10.2 Fastenings. Furring strips intended tosupport plaster or acoustical materials on the ceil-ings should be nailed and tied securely by 16-gage


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wire to the underside of the joists. When wooden secure anchor. When open-web joists are used,joists are used, convenient hangers are formed by nailing is accomplished by means of metal nailingdriving 10-d nails into each side of the joists. A grooves or wooden nailers. Wire loops, encirclingwire extending from one nail to another, looped the furring strips and the lower chord of the joists,and drawn taut across the furring strip, forms a can be spaced as required.

SECTION IV—FIRE PROTECTION

5.4.1 General noncombustible. Similarly, partitions or ceilings

In the course of necessary repairs to buildings andstructures, fire protection features will be reexam-ined and any deficiencies corrected promptly. Ade-quate fire protection is a function of design, butsuch changing conditions as additions to buildingsand structures, change in occupancy, or introduc-tion of increased operational hazards may requireupgrading of protective features or additions tothem. In any case, the effectiveness of fire protec-tion features depends on regular inspection, care,and maintenance. (Fire protection standards may beobtained from the National Fire Protection As-sociation (NFPA) Standards.) (Air Force Standardsare found in AFM 88-15.) The extremely rapidflame spread that occurs on the surfaces of com-monly used materials has been the cause of manycatastrophes. In view of the past record, the use ofcombustible wall and ceiling finishes (includingwallboard and acoustical units) having high flame-spread ratings is prohibited. Certain interior finishesthat have a rapid flame-spread rating were widelyused in the past and remain in use in somebuildings. The generation of smoke and fumes re-sulting from the combustion of material must alsobe taken into consideration. Interior wall and ceil-ing finishes are applied over structural framing of abuilding and cover a considerable portion of theindividual walls or ceilings. Such materials includedecorative finishes, acoustical corrections, and sur-face insulation. Surface coverings of wallpaper, notexceeding 0.025 inch thick, or a material with nogreater fire risk than wallpaper, do not contributesignificantly to fire hazards when applied over anoncombustible base. Generally, plaster finisheshave been accepted by building codes, and wall- 5.4.2.1 Firewalls. Firewalls are protection againstpaper or paint finishes over noncombustible sur- the horizontal spread of fire only if they are intact,faces are considered nonhazardous if any coatings and if openings were permitted, are properlyare not applied one over the other. protected against passage of smoke or heat. In-

5.4.1.1 Noncombustible Interior Finishes. Fire re-sistance and flame spread are different properties ofconstruction materials. Fire-resistant ratings havebeen established for wall, partition, and ceilingconstruction by responsible and extensive labo-ratory tests. Conventional wall construction, suchas brick, concrete, hollow tile, and concrete orgypsum block units surfaced with plaster of the re-quired thickness, is considered nonhazardous and

constructed of assemblies of wood or metal studsand joists, or of metal, gypsum, or wood lath sur-faced with cement, lime, or vermiculite plaster havenonhazardous interior surfaces and, depending onthe assembly, the required fire rating. Sheet-metalcovering applied directly to wood joists or over oldplaster ceilings, although superior to highlycombustible materials, offers little resistance andincreases the effort required to extinguish firesstarting in concealed spaces between the joists.

5.4.1.2 Insulation and Sound Control Materials.Insulation and sound control problems are similar,principally because the same materials (treated anduntreated) are often used for insulating buildingsfor heat or cold (thermal insulation) and for soundcontrol (acoustical correction).

5.4.1.3 Fire Resistance. Noncombustibleinsulating material, such as mineral or glass wool,may increase fire resistance if it will stay in placeand not settle and produce voids. Standard firetests have shown that mineral wool in the hollowspaces between studs increases the fire resistanceof metal lath and sand gypsum plaster on woodstud partitions by about 30 minutes. For gypsumboard facing on wood stud, the fire resistance is in-creased by 10 to 20 minutes.

5.4.2 Alterations

When alterations are necessary to existing build-ings, the fire protection features should be reexam-ined to correct deficiencies and provide such addi-tional measures as the new use requires. The fol-lowing features are most important.

terior finish repairs must be accomplished withoutdamage to firewalls, and finishes applied shouldhave a flame spread rating equal to finishes used onother interior walls for a particular occupancy.When hazards are increased in existing buildingsand structures, firewalls should be added as neededto subdivide the space into suitable limited fireareas; this can often be done economically byincreasing the fire resistance of existing walls and


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installing fire doors. If area limitations require the presence of combustible debris. Materials usedfirewalls through combustible roof structures, the for insulation will be noncombustible. Any draftwalls should be parapeted. stop helps slow the spread of fire, but complete fire

5.4.2.2 Vertical Openings. The enclosure of verti-cal openings is most important in preventing thevertical spread of fire. In fact, it is probably thelargest factor in connection with life and propertysafety in multistory buildings. If masonry wallscannot be placed around open stairways or elevatorshafts in an existing building, metal lath and plaster, 5.4.2.5 Skylights. Skylights and other small struc-or other lightweight construction of equal fire tures on the roofs of buildings should have a fire-resistance, may be used. Any enclosure is pref- resistance rating appropriate to the constructionerable to open stairs or elevator shafts. and occupancy. Skylights should be maintained to

5.4.2.3 Horizontal Openings. All wall openingswill have fire protection features appropriate to theoccupancy of the building and structure. This is 5.4.2.6 Ventilation Ducts. Ventilation or exhaustespecially important for areas where hazardous and intake ducts extending through roofs or wallsprocesses are carried on or hazardous materials are should be of noncombustible materials. Ductsstored in buildings or structures with a large total should be cleared of obstructions as required. Ven-floor area. The adequacy of horizontal opening tilation hoods, ducts, and filters in kitchens shouldprotection should be checked and preserved in the be periodically cleaned to remove grease accumu-course of interior repairs. If swinging fire doors are lation that may cause fire. Devices to prevent theused to replace sliding doors, such doors must entrance of sparks or brands, such as baffle plates,swing in the direction of the emergency exits. vanes, dampers, and metal screens, should be

5.4.2.4 Concealed Spaces. Concealed spaces ex-posed in the course of repairs will be checked for

stopping may be difficult in open-joist channels andstud-spaced wood construction. Fire stops shouldbe used between the wood joist and sills. The useof fire-retardation paint or solution may be helpfulin particular cases, but this provides only atemporary measure of protection.

insure their effectiveness in preventing the entranceof fire and venting interior fire or explosion.

checked regularly for proper setting and good condition.

SECTION V—ACOUSTICS

5.5.1 Acoustical Problems construction keeps out sound by preventing the

Acoustical materials applied on walls, partitionsand ceilings of theaters, auditoriums, and manyother occupancies absorb noise and aid hearing byreducing echoes and reverberation. Two acousticalproblems are to be considered. One is the treatmentof a room or building to keep out exterior sound,and the other is the treatment of a room interior toeliminate echo and reverberation by soundabsorption or diffusion to reduce objectionablenoise levels.

5.5.1.1 Exterior Sound. Insulation from exteriornoise is sometimes part of the interior sound-absorption problem. The best resistance to noisepenetration usually can be obtained with heavyrigid walls and floors, or multiple-layerconstruction separated by airspaces. Such

vibration of the wall or floor. Any mechanicalconnection across the intervening airspaces in astructurally separated wall increases soundtransmission. For hollow walls not structurallyseparated, such as ordinary wood stud partitions, afill of noncombustible material between the studsslightly improves the sound insulation.

5.5.1.2 Sound Absorption. For best results, soundabsorption requires porous or low-density materi-als, but it is impossible to set rules applying equallyto every installation. However, it is necessary touse only noncombustible materials that do not havesurface flame-spread characteristics and will notadd fuel to a fire that may occur in the treated spaces.


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CHAPTER 6

FLOORS AND STAIRS

SECTION I—GENERAL

6.1.1 Types of Floors and Coverings and a permanent log should be maintained.

Floor materials found in buildings and structuresfor various occupancies include wood, concrete,terrazzo, magnesium oxychloride, clay tile (quarryand ceramic mosaic), mastic, metal, cork, andrubber. Conductive floors are normally peculiar tooperating rooms and delivery suites in hospitals anddispensaries. Spark-resistant floors shall be placedin ammunition storage areas, where explosives arestored. Common floor coverings include linoleum,vinyl tile, vinyl-asbestos tile, asphalt tile, cork tile,rubber tile, and resinous coatings for monolithicfloors. Floor structures, finishes, and coveringsshould be suitable for the operations conducted onthem. All components should be maintained in sucha manner that the complete floor will givesatisfactory service. No operations which mightimpair the floor structure, covering or finish shouldbe conducted until suitable modifications orprotective measures have been undertaken.

6.1.2 Types of Stairs

Maintenance instructions are provided herein forinterior and exterior stairs of wood, concrete, ter-razzo, metal, and composition materials.

6.1.3 Inspection of Floors, Floor Covering, andStairs

6.1.3.1 Floors. Wood floors should be checkedquarterly for loose nails; warped, cupped, or looseboards; raised ends; slivers; cracks; loose knots;raised nails; and water or other damage from im-proper cleaning, condensation, and wood decay.Concrete floors should be inspected annually fordusting, spalling, cracking, and settling. Terrazzofloors should be inspected annually for loose orbroken segments and damage from impropercleaning. Magnesium oxychloride floors should bechecked annually for water and other damage fromimproper cleaning. Clay tile floors should beinspected annually for missing, loose, or brokentiles, open joints, and damage from impropercleaning. Mastic-topped floors should be checkedannually for damage from improper cleaning. Con-ductive floors should be tested for conductivitywith an ohmmeter at least quarterly or after repair,

Conductive flooring will meet the conductivity re-quirements of the National Fire Protection Asso-ciation (NFPA) Standards. Metal floors should beinspected annually for corrosion.

6.1.3.2 Floor Coverings. Floor coverings shouldbe checked annually. Asphalt and vinyl tilecoverings should be inspected for missing, loose,and broken tiles, or open joints; seriousindentations; burns; and damage from impropercleaning. Linoleum and other flexible sheetcoverings should be inspected for loose seams,buckling, serious indentations, and damage fromimproper cleaning.

6.1.3.3 Stairs. Interior and exterior stairwaysshould be inspected at least quarterly for adequacyof support and safe condition of components. Stair-ways should be checked, as appropriate, forcracked, weathered, or rotted wood framing; forsettled, cracked, or spalled concrete; and for rustedor loose metal supports or parts or loose nails onwood stairs. Treads should be inspected for looseor broken tread nosing, excessive wear, paint ortread covering deterioration, and loose, eroded, orslippery tread surfaces. Exterior treads should besloped (or drilled) so as to drain properly. Hand-rails should be inspected for loose fastening andmaterial deterioration. Newel posts and balustersshould be checked for looseness and missing parts.

6.1.4 Custodial Services

Proper and timely custodial care will materiallyprolong the life of floors and finishes. The MilitaryCustodial Tri-Services Manual (TM 5-609,NAVFAC MO-125, AFP 91-30 and 92-1) providesCommanders at DOD installations with methods ofaccomplishing custodial services and establishescleaning standards.

6.1.5 Safe Floor Loads

CAUTION: Do not load floors beyond their de-signed safe load capacity. Permanent and easilyread signs or placecards, conspicuously showingthe safe load capacity in lb/ft 2 of the floor, shouldbe placed on each floor of a building. Such posting


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is also necessary for slab-on-ground floors in ware- on them are likely to exceed the bearing capacity ofhouses, equipment shops, etc, when imposed loads the underlying soil.

SECTION II—WOOD FLOORS

6.2.1. Wood-Strip and Parquet Floors c. Scrape or machine-sand all high joints to

Strip flooring is usually of oak, pine, maple, beech,pecan or birch and is generally laid over a woodsubfloor. Strip flooring should be of tongue-and-groove material and be blind-nailed. Parquet floor-ing may be solid block or laminated block in thehardwood species and may be nailed or installed inadhesive on concrete slab, plywood subfloor, orhardwood underlay. For gymnasiums, squash andhandball courts, and ballrooms, special applicationmethods are used as specified in guide specifica-tions for military construction and in accordancewith the manufacturer's instructions.6.2.2 Reconditioning

6.2.2.1 Defects in Wood Floors. Some of the de-fects found in wood floors and the causes of thesedefects are listed below:

a. Wide cracks between strips and at end joints,caused primarily by use of unseasoned wood forfloorboards and understructures.

b. Raised flat grain and excessive splintering,caused by oversanding or improper cleaning withexcessive water and strongly alkaline soap or otherdamaging cleaning agents.

c. Irregular holes in floor where upended seg-ments have been torn out during mopping or re-moved to prevent accidents.

d. Unevenness at joints, caused by inadequatenailing or loosening of nails under heavy trafficduring the shrinking period.

e. Wood decay, frequently caused bycondensation under the floor.

f. Failure to provide for expansion at room pe-rimeter, causing floor to buckle.6.2.2.2 Reconditioning Methods. Floors that havebecome appreciably worn, cut, gouged, indented,or stained or that have splintered, loose, or warpedstrips or planks should be refinished or covered.Pine- or hardwood-strip flooring can be sandedabout / inch or nails are exposed before replace-3

16ment or overlaying is needed.6.2.3 Refinishing

6.2.3.1 Floor Preparation. Perform the followingcorrective work before removing old finish, refin-ishing, or covering floors:

a. Renail all loose and warping boards.b. Remove all tacks and set nail heads well

below the floor's surface. made in 12 grades. Flint (sand) papers having glue

make them level with adjacent floorboards.d. Remove and replace boards that are

damaged beyond reconditioning.e. Remove loose splinters and fill all holes and

large cracks with crack filler.f. Remove grease, oil, and other foreign

matter.6.2.3.2 Refinishing Areas with Worn Finish. Areaswhere wood-floor finishes are worn may sometimesbe reconditioned as follows:

a. If possible, clean the floor by the drycleaningmethods, or use a commercial-type "finish renewer'available from most flooring contractors. Mostwood-flooring manufacturers recommend that nowater be used on the maintenance of wood floors.However, if scrubbing is necessary, use a mopdampened in all-purpose synthetic detergentsolution.

b. Liberally apply a varnish-type sealer thatconforms to Federal Specification TT-S-176.Spread or spray it along the grain of the wood.

c. After the sealer has dried completely, buffthe floor with a floor-polishing machine, usingNo.1 steel wool pads. If portions of the floor looklusterless, dry, or dead after the buffing, continuesealing and polishing until the floor surface has auniform appearance.

d. Apply spirit-type liquid or paste wax. Buffthe wax after each application.6.2.3.3 Sanding

a. Equipment. Power-operated sandingmachines are the most satisfactory means ofpreparing wood floors for refinishing. The operatorshould wear an approved respirator or dust maskwhile sanding. Abrasive paper, commonly calledsandpaper, is made with paper or fabric backing.For machine use, a fabric-backed or fabric-reinforced paper backing is recommended. Themineral cutting agent glued to the face of the papermay be flint (Federal Specification P-P-105), garnet(Federal Specification P-P-121, waterproof), orsilicon carbide (Federal Specification P-P-101,waterproof). Cutting surfaces are designated closecoat (cutting grits covering the entire face) or opencoat (grit covering about half the cutting surface).Open-coat paper is recommended for sandingmaterials, such as paint and varnish, that tend toclog spaces between the grits. Flint papers are


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binders must not be stored where they will be in the removal operation. Edges that cannot besubject to oil, moisture, or extreme heat and cold. reached by a sanding machine should be hand-Old brittle paper can be softened by dampening the scraped. The floor should then be sealed and waxedbacking. The following table (table 64) is a guide to as described in paragraph 6.2.3.2. The final sandingsandpaper selection for floor finishing: for parquet flooring must be with a disk sander.

TABLE 6-1: Guide to Sandpaper Selection for FloorFinishing

Grade Type Use

3½ . . . . . . . . . Open . . . . . . . . Preliminary removal ofstubborn varnish,shellac, floor oil, wax,and deep-penetratingfiller compounds. Notto be used for cuttinginto wood surfaces.

3 . . . . . . . . . . Open . . . . . . . . Used in place of No.3½for surfaces of lessresistance; is preferredif it does the requiredwork.

2½ . . . . . . . . . Open . . . . . . . . Preliminary removal offloor finishes such asshellac, wax, floor oils,alcohol stains, andlacquered surfaces.

2 . . . . . . . . . . Close . . . . . . . Use instead of No. 2 andNo.2½ open coat where surface permitscutting withoutgumming. Closed coatshould be used inpreference to opencoat wheneverpracticable.

1½ . . . . . . . . . Close . . . . . . . Use as a first paper on all new floors.

1 . . . . . . . . . . Close . . . . . . . Use as followup for No.2and No.2½ in all cases.

1 . . . . . . . . . . Close . . . . . . . Use the same as No. 1open coat to provide asmooth floor finish.

½ . . . . . . . . . . Close . . . . . . . Use as final finish on most floor work.

/ & / . . . . . .1 20 0 Close . . . . . Use as final finish on

best hardwood floorwork.

/ & / Close . . . . . . .3 40 0 Use for finishing fine

woodwork such asfurniture and forrubbing down paintand varnish finishes.

b. Procedure. Old varnish, shellac and waxmaterial should be removed from the floor with theproper type of abrasive paper. First, go over thefloor twice diagonally with coarse paper, avoidingdeep abrasive marks in the wood; then finish withfine paper or steel wool parallel with the grain. Seefigure 6-1. No attempt should be made to cut wood

Additional information on floor sanding may befound in the Tri-Services Manual, "Paints andProtective Coatings.”6.2.3.4 Use of volatile Liquids.

a. Safety Precautions. In exceptional cases,when old floor finishes cannot be removed bysanding or scraping with an abrasive, highly volatileliquids may be used. These liquids, as well as thoseused in floor refinishing, include paint and varnishremover, varnish, liquid paint, and shellac, whichhave flashpoints as low as 40E F (4.5E C).Refinishing should be done only under expertsupervision, with attention to the followingprecautions:

(1) Use rubber gloves and face masks(respirators) when working with highly volatileliquids, varnish, varnish remover, liquid paint, andshellac.

(2) Remove from the area all personnel notengaged in the work.

(3) Provide all possible natural ventilation.(4) Disengage the main electric switch for

the entire building and work under natural light. Ifthis is not practicable, disconnect all electricappliances in the vicinity, including such equipmentas water coolers and soft-drink dispensers, beforeapplying volatile liquids. Do not reconnect theappliances until the liquids have completely driedon the floor.

(5) Shut off the main gas valve for thebuilding. If this is not practicable, extinguish thepilot lights on all gas equipment and do not relightthem until the volatile liquids have completelydried.

(6) Prohibit smoking and the use of openflames during application of the liquids and for 1hour after they have completely dried.

(7) Clean only a small area of floor at atime.

(8) Restrict the amount of liquid on hand tothat needed for the immediate operation; immedi-ately return any unused liquid to its proper storageplace. Do not use open containers for storage.

(9) Provide covered metal containers forused cleaning rags. Remove the cans beforesecuring the building.

(10) Place the residue from sandingmachines in cans, wet it down, and promptlyremove the cans from the building.


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(11) Notify the fire department before removed by the use of steel wool saturated withoperations are started, and observe any additional turpentine.pre cautions fire officials may require.

b. Application. Old varnish and paint finishesmay be removed from a floor by application of anorganic-solvent remover conforming to FederalSpecification TT-R-251. The remover is brushedon and allowed to stand until the varnish or paintsoftens. The old finish is then scraped off with asteel blade scraper or rubbed off with steel wool orexcelsior. Oil finishes may be removed by a watersolution of trisodium phosphate, washing soda, orcommercial cleaner. The liquid is applied to thefloor, a small area at a time, allowed to stand for afew minutes, and then scrubbed off with a stiffbrush. The floor should be scrubbed and mopped toa dry or slightly damp surface. Old shellac may be

6.2.4 Replacement of Wood Floors

6.2.4.1 Preparation. Before laying finished woodfloors, inspect wood subfloors, replace defective orotherwise damaged boards, and renail boards thatdo not have a firm, tight bearing. Broom-cleansubfloors of plaster, dirt and other foreign matter.When the subfloor is judged to be clean and dry,put down a layer of asphalt-saturated felt conform-ing to Federal Specification HH-R-595. Lap edgesand ends of felt 4 to 6 inches and turn up underbaseboard not less than 3 inches. Finished flooringwill not be brought into building until plaster andmasonry is thoroughly dry.

6.2.4.2 Laying Wood Flooring. Cut all boards to flooring. The first strip along the wall must beeliminate knotholes, loose knots, and damaged por- straight and parallel to walls for it affects directiontions. Blind nail all dressed and matched flooring of succeeding strips. Drive each strip tight againstwith straight shank cut steel, or spiral or screw- previously laid strip before nailing. End-matchedtype shank flooring nails. For 25/32-inch flooring joints may be made random. Make square enduse eightpenny nails. For face nailing, use 8-d fin- joints occur over bearings. Stagger all end joints soishing nails and set the heads. Normally, flooring there are at least two continuous boards on eachshould be laid perpendicular to the joists. Nails side of board joints. Set heads of all exposed nails.should extend through the subfloor into the joist. Leave an expansion space of not less than ½ inchStrip flooring overlying existing strip flooring on all sides next to walls, but not wider than will beshould be laid perpendicular to the existing covered by the base shoe, quarter round, or door


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threshold. Finish flooring by machine sanding. h. Dry-sweep the area to remove all particlesHand scrape around edges and other surfaces not of dust.accessible by machine.

6.2.5 Patching Wood Floors filler conforming to Federal Specification TT-F-

6.2.5.1 Procedure. If floor damage requires replacement of strips or planks, the followingprocedure should be observed:

a. Make two longitudinal cuts in the damagedstrip or plank. See figure 6-2, detail A.

b. Remove the section between the two cutsby cutting the strip with a chisel at midpoint. Seefigure 6-2, detail B.

c. Remove the remainder of the damagedstrip, taking care not to damage the tongues andgrooves of adjoining boards. See figure 6-2, detailC.

d. Remove the lower part of the groove of thenew closure strip or plank. See figure 6-2, detail E.

e. Insert the tongue of the closure into thegroove of the adjoining board for face nail with twoeightpenny, annular-ring finishing nails. Whenpossible, the end joints should be located so thenails will enter the joist. In new closure areas offlooring laid in mastic on concrete, remove theexisting mastic and apply new mastic of the typerecommended by the flooring manufacturer beforeinstalling the new closure.

f. Set exposed nails. See figure 6-2, detail D.

g. Dress the new portion to the level of theadjacent floor by sanding both areas to acontinuous, smooth plane.

i. On open-grained woods, brush on a paste

336. After the filler has partially dried, rub it intothe pores of the wood with a circular motion usingexcelsior or burlap. Wipe the surface lightly toremove any surplus filler. Inadequate filling is in-dicated by pockmarks and results from wiping offtoo much of the filler or from unusual absorptionby the wood. Eliminate such deficiencies by repeat-ing the filler application.

j. Seal and wax the floors as described inparagraphs 6.2.3.2 and 6.2.3.3 or finish to matchexisting.

6.2.6 Creaking Floors

Creaking in an old floor may be the result of one ormore causes such as shrinking or warping of theboards, insufficient initial nailing, loosening of thesubfloor, warping of joints, or the presence ofbuilding settlement which throws the floor out oflevel. If the boards have lifted from the joists, placea wood block on the loose spot and drive downwith a heavy hammer or maul. A piece of oldcarpet or other material placed under the block willprevent marring the finished floor. If floor will notstay down, drive several nails through both finishand subfloor into the joists to draw the floor downtight. Drive nails heads to within ¼ inch of floor,then finish driving and set with nail set. Fill holesover nail heads with putty or plastic wood, coloredto match floor finish.


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6.2.7 Preparation for Rug or Carpet Covering 6.2.9 Industrial Wood-Block Floors

Wood floors that are to be covered with rugs must 6.2.9.1 Description. Wood-block flooring isbe sealed to prevent damage from dust that seeps usually of southern yellow pine, oak, western larch,through the covering. Refer to paragraph 6.2.3.2, western hemlock, and Douglas fir. Wood-blockreconditioning areas with smooth finish, except flooring should be pressure treated withomit wax coat. Provide padding or underlays to preservative. It usually shows all end grain on theprotect rugs from dust seepage and to prolong rug wearing surface. Blocks are made in sizes ranginglife. from 1½ to 4 inches wide, from 3½ to 8½ inches

6.2.8 Overlaying of Wood Floors withResilient Flooring

When wood floors can no longer be resanded andit is not desirable to replace them, they may beoverlaid with resilient flooring. Procedures for theoverlaying of wood floors with resilient flooring areoutlined in Section 6.9, Resilient Floor Covering.

long, and from 2 to 4 inches thick. Grooves areusually cut into the sides and ends of individualblocks, or the vertical corner surfaces are beveledto permit easy penetration of binder into the jointssurrounding each block. Blocks are usually laidindividually in an adhesive mastic and the jointsfilled; however, factory-assembled strips of blockslaid in mastic may be used.


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6.2.9.2 Maintenance. Sweeping wood-block floors of tools or parts that may be dropped. Repairwith a stiff bristle broom or a power sweeper woodblock floors with concrete as follows:should keep them dirt-free. In areas where accu-mulation of dirt and oils requires more than normalsweeping, the floor may be scraped with a metalscraper or cleaned with a power buffing machineequipped with a wire-bristle brush or coarse steelwool pads. Oil or water spills should be removedimmediately and the area covered with an oil- andwater-absorbing compound conforming to FederalSpecification P-S-865. The compound should beswept up after it has absorbed the oil or water. Donot use water on wood-block flooring. Waterenters the pores of the blocks or the cracksbetween them and causes the floor to warp orbuckle.6.2.9.3 Repair. Wood-block floors are generallyrepaired by replacement of splintered, cracked, andloose blocks with new blocks, matching the originalmaterials as closely as possible. Methods of re-pairing floors are as follows:

a. Large Areas. When large areas or the entirefloor surface must be replaced, the new floorshould be installed according to specifications forthe original floor. If the materials originally speci-fied cannot be obtained, they should be matched asclosely as possible, and the manufacturer’s recom-mendations followed. Both coal-tar pitch and as-phalt products are used in the installation andtreatment of industrial wood-block floors. Materi-als of the respective types used in the original in-stallation should be used for replacement. Coal-tarpitch and asphalt are not compatible and must notbe in contact with each other. Test existing mate-rials to determine their composition. Concrete maybe used to replace large areas of deterioratedblocks where operational conditions permit andwhere the weight of the concrete will not exceedthe design limitations of the structure. Concreteprovides the hardness and toughness necessary toresist heavy loadings but does not provide the re-siliency needed for foot comfort or for protection

(1) Lay out the area to be repaired inrectangular lines and include all defective and looseblocks.

(2) Remove all blocks within therectangular area.

(3) Clean the subfloor of all looseparticles, dust, oils, and grease.

(4) Proportion, place, and finish the newconcrete as described in paragraph 6.3.4.

(5) Replace all expansion joints and installnew expansion joints in the concrete every 20 feetin both directions.

b. Small Areas. Small areas of wood-blockfloors are repaired by replacement of deterioratedor loose blocks with small blocks, matching exist-ing materials as closely as possible.

(1) Remove all deteriorated and looseblocks in the area.

(2) Thoroughly clean the subfloor,removing all loose particles, dust, oil, and grease.

(3) Be certain that the subfloor andsurrounding blocks are thoroughly dry. Then, applyone coat of the floor manufacturer’s recommendedprimer to the subfloor and sides of the surroundingwood blocks.

(4) When the primer is thoroughly dry,apply a coat of coal-tar pitch or plastic bituminouscement, as suitable to the subfloor in the quantitiesnecessary for permanent adhesion between thesubfloor and wood blocks.

(5) Fit the individual blocks or strips ofblocks into place, matching the existing floor linesas closely as possible. Fill any voids of less than onefull block with a section of a block cut to fit. Retainexisting expansion joints.

(6) Fill the joints and finish or seal thefloor, as necessary, according to the manufacturer’srecommendations.

SECTION III—CONCRETE FLOORS

6.3.1 Maintenance spalling, pitting and other deterioration; such floors

Concrete floors of proper composition, installation,and curing require comparatively little maintenanceunless they are exposed to the following: severeabrasion and heavy vehicle loads from industrialtraffic; the deteriorating effects of grease, oils, andfood acids such as are encountered in kitchens,sculleries, bakeries, meat-cutting plants, and similarfood preparation spaces; or caustic soaps andsolutions. The corrosive agents in highly acidic oralkaline liquids attack concrete floors and cause

may be overlaid with resinous (epoxy, polyester)industrial (tru-welded-on) type topping or withresinous terra 330. When trucking is done overconcrete floors, as in aisles of warehouses, trucksshould be fitted with wide-faced wheels with rubbertires. If vehicle abrasion and shock continue to raisemaintenance demands, the application of heavy-duty topping to the concrete should be considered.CAUTION: Avoid painting concrete floors exceptfor functional requirements, such as marking safety


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lanes or similar areas. Painting for appearance is course. Clean out all loose material with a stiffunjustified and impractical. Traffic areas on painted brush and compressed air. First saturate the area tofloors will wear first, making the floor unsightly be patched and the adjoining surface with water.and presenting a difficult cleaning problem. Cost of Keep them wet for at least 4 hours. Mop up therepainting constitutes an unnecessary expenditure excess water. Spread a thin layer of neat port landof maintenance funds. Much useful information on cement on the sides and bottom of the crack.concrete floors can be found in publications by and Broom the cement into the surface of the concrete.available from the Portland Cement Association As soon as the cement has absorbed enough waterand in the “Concrete Manual” published by and to form a sticky paste, place the new mortar. Tampavailable from the Bureau of Reclamation, U.S. the mix into the crack and with a screed, bring it toDepartment of the Interior. Also refer to pavement a level slightly higher than the adjoining floor. Letmanuals. it set for about 1 hour. Tamp it hard and trowel it

6.3.2 Repairs

Concrete floors should not be repaired until causesof defects have been determined and preventablecauses have been eliminated.

6.3.2.1 Cracks.

a. Causes and Corrections. Cracks in concretefloors may be caused by shrinkage, expansion orcontraction due to temperature changes, settle-ment, or lack of rigidity of supporting beams orother structural members. When such movementsare recurrent and can be eliminated only by majorstructural changes, little can be done except to keepthe cracks filled with a mastic material. In manycases, comparatively small cracks may be filledwith varnish or resin. Although the cracks willremain visible, they will not leak or gather dirt.When the cause of large cracks has beendetermined and corrective measures taken to elimi-nate further cracking, the cracks can be perma-nently repaired by filling them with nonshrinkingcement mortar. Patching will not permanentlycorrect cracks in slabs on grade caused by verticalmovement resulting from exceeding the design loadof the slab, inadequacy of the base, or insufficientbearing capacity of the soil. Slab failure under thesecircumstances may sometimes be corrected by mudjacking. Following completion of mud jacking,cracks should be cleaned and filled with an epoxyresin preparation, which should be used only inaccordance with the manufacturer'srecommendations. Complete replacement of slab-on grade floors is often the only feasible method ofrepair.

b. Procedure for Repairing. Chip or rout outcracks to be repaired. Form a channel of at least 1inch deep, with vertical sides. If the crack extends Improperly constructed floors that have toppingthrough the structural slab, cut a V-shaped groove, finish may be roughened by traffic or pitted byat least 2 inches deep, in the bottom of the channel, heavy impacts. Such floors can be restored to satis-resulting in a total depth of 3 inches. If the crack factory condition by grinding off the rougheneddoes not extend through the base and if the top surface. If the concrete is of such poor quality thatcourse is less than 3 inches thick, chip the V- the surface will soon be roughened or pittedshaped groove only to the depth of the wearing again,it would be more economical to resurface or

to the level of the adjoining floor. Keep the newconcrete wet and protect it from traffic for about 7days (3 days if high early strength is used).

6.3.2.2 Patches.

a. Preparation. Lay out patches in rectangularlines to include all defective surfaces. The edges ofthe areas to be patched should be saw cut. Chip outthe old concrete to a depth of at least 1 inch oruntil sound concrete is reached. Roughen thechipped surfaces and provide vertical sides. Cleanout all the loose particles and dust. Saturate theprepared areas and adjoining surface with waterand keep them wet for at least 4 hours. Removeany pools of water that may accumulate on theroughened area, neatly spread a layer of portlandcement uniformly, and thoroughly broom it into thesurface. As soon as the cement has absorbedenough water to form a sticky paste, apply thepatching mixture.

b. Patching Prepare a patching mixtureconsisting of 1 part portland cement, 1 part well-graded sand, and 2 parts pea gravel or crushedrock, graded from c to d inch. Mix the dryingredients of the concrete thoroughly. Use nomore than 4½ gallons of mixing water for eachsack of cement. Continue the mixing for at least 1½minutes after all the ingredients, including water,are in the mixture. The concrete, after being placedon the slab, should be vibrated, rolled, or tamped inplace. Screed to proper level and float. Steel trowelto a hard finish. Cover the new concrete with wetburlap or another approved method (spray paint),protect it from traffic, and keep it wet for 7 days (3days if high-early strength cement is used).

6.3.3 Refinishing by Grinding


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replace it with concrete of the proper quality. Con- remains on the finished surface. Test the surface acrete surfaces often have numerous hairline cracks with straightedge to detect high and low spots andand crazes as a result of improper curing. If the eliminate them. Finish the surface with a steelcracks are not too deep, they may be eliminated by trowel. Allow the concrete to become hard enoughgrinding the floor. Concrete floor surfaces are that mortar will not accumulate on the trowel. Inground by the method used in finishing terrazzo the final troweling, a ringing should be produced asfloors, which requires highly skilled labor under the trowel is drawn over the surface. Do notadequate supervision. sprinkle dry cement or a mixture of dry cement and

6.3.4 Resurfacing

6.3.4.1 Suitability of Floors. Wearing surfaces ofconcrete floors that are spalling or abrade easilyunder foot traffic should be resurfaced or covered.Old floors that have been subjected to service toosevere for the quality of the surface can be resur-faced with a heavy-duty topping. If the floor designload permits and if raising the floor level is not ob- Concrete floors in receiving rooms, loading plat-jectionable, a new topping can be placed directly on forms, and other locations that are subjected tothe old slab. impact from falling objects, heavily loaded steel-

6.3.4.2 Preparation. All dust, paint, grease, oil,and loose materials should be cleaned from the oldfloor before it is resurfaced. Areas that have theoriginal troweled finish should be roughened with 6.3.5.1 Grilles. Steel floor grilles are set in con-a pick or grinding tool. Expansion and construction crete, with openings between the grilles filled withjoints should be retained. Whenever practicable, the concrete. Grilles should be installed according tonew topping should be at least 2 inches thick and the manufacturer’s recommendations. The top sur-reinforced with 2- by 2-mesh galvanized welded faces of the grilles should be level with the finishedwire fabric, 21 pounds per 100 square feet, placed floor.approximately in the middle of the thickness of thenew concrete.

6.3.4.3 Concrete Mixture. New concrete should mixture containing iron aggregate, suitable for ap-consist, by volume, of 1 part portland cement, 1 plication as a part of a new concrete topping by thepart graded sand, and 2 parts pea gravel or crushed dusted-on method. The mixture should be free fromrock, graded from c to d inch. It should be of the nonferrous metal particles, oil, grease, and solublestiffest consistency practicable so that the strike-off alkaline compounds. It should be water-absorbentboard or straightedge may be used in a sawing and contain not more than 0.075 percent of water-motion. Not more than 4 gallons of mixing water, soluble material. A cement-dispersing agent and aincluding the moisture in the aggregates, should be pozzolanic material that will combine with free limeadded for each sack of portland cement. Use not to form a water-insoluble compound should bemore than 5 gallons when floating is done by hand. combined with the metallic aggregate. In applyingThe concrete should be mixed for at least 1½ the finish to the topping, strike off the topping trueminutes after all ingredients, including the water, and screed it to the finished elevation. Apply theare in the mixer. dry mixture over the freshly screeded concrete at a

6.3.4.4 Application of Finish. Keep the base slabthoroughly moist for a 24-hour period before plac-ing the finish, but allow no pools of water toremain when the wearing course is placed. Brooma thick coat of neat cement grout into the surfaceof the slab for a short distance ahead of the top-ping. Before the grout has hardened, place thewearing course and bring it to the established gradewith a straightedge. Compact the wearing courseby rolling with weighted rollers or tamping withiron tampers. Float the surface with a wood float orpower-floating machine, making sure no water

sand on the wearing course to absorb moisture orstiffen the mix. This will make the surface weakand produce cracks and crazes. Cover the concretewith wet burlap as soon as it has hardened enoughnot to be damaged by the covering, and keep it wetfor at least 7 days.

6.3.5 Heavy-Duty Floors

tired trucks, or sliding loads usually require pro-tection, such as steel floor grilles or surface treat-ment.

6.3.5.2 Surface Treatment. Metallic monolithicsurface treatment consists of a factory-prepared

uniform rate of 60 pounds per 100 square feet ofsurface. After the mixture has absorbed water to auniform appearance, rod it with a straightedge to auniformly true surface. When absorption iscomplete, compact the finish by rolling with heavyrollers or by floating with motor-driven floats ofthe metal disk type. Add material to low spots untila uniform appearance is obtained. Follow thecompaction with troweling by hand or machine toproduce a smooth, hard, and impervious surface.Cure heavy-duty floors as recommended inparagraph 6.3.4.4.


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6.3.6 Nonslip Floors full 241/2 inches on each sheet, so that the felt does

A nonslip floor is required in certain areas. In re-surfacing floors in such areas, nonslip aggregatesmay be mixed with the concrete or sprinkled on thesurface of the wearing course just before finaltroweling. More aggregate is required when it ismixed with the concrete, but distribution on theaggregate is usually more uniform. Nonslip aggre-gates should be particles of aluminum oxide, emeryore, or ceramically bonded abrasive, such asCarborundum, ranging in size from / to ¼ inch.1

32If mixed with the concrete, ¾ to 1 pound ofaggregate is required for 1 square foot of floorwhen topping is ¾ to 1 inch thick. If sprinkled onthe surface, ¼ to ½ pound of aggregate is requiredfor 1 square foot of floor. To apply the aggregatedirectly to the floor, dampen the abrasive aggregatethoroughly before spreading, and tamp it flush withthe unhardened surface with a steel trowel. Becareful not to bury the chips. Cure the floor asrecommended in paragraph 6.3.4.4. After curing,scrub the floor with a floor machine, using steelwool pad (or rub it with an abrasive brick andwater) to remove cement film and slightly exposethe nonslip aggregate.

6.3.7 Waterproofing

6.3.7.1 Causes of Seepage and Damage. Concretefloors that must resist the percolation of water ap-plied on the upper surface are usually waterproofedduring construction. Improper waterproofing orbuilding settlement may require remedial action.Floors usually leak at the line where the floor joinsthe wall, through cracks that may be very small,and through porous concrete. If the surface of aconcrete floor can be raised, the floor can bewaterproofed with a bituminous membranewaterproofing.

6.3.7.2 Waterproofing Methods. Application of bi-tuminous membrane waterproofing (felt and coal-tar pitch or asphalt) is similar for concrete floorsand masonry walls. If coal-tar pitch is used, coatthe concrete base uniformly with hot pitch con-forming to Federal Specification R-P-381, Type II(also ASTM D-450). Use not less than 40 poundsper 100 square feet, and lay over this two or fourlayers (depending on extent of leakage and hydro-static pressure) of coal-tar pitch-saturated felt con-forming to either ASTM D-173 cotton-fabric felt,or ASTM D-1327 burlap-fabric felt, or ASTM D--1668 glass-fabric felt. Lap each layer 24½ inchesfor 36-inch-wide material (22 inches for 32-inchmaterial) over the preceding layer, and make end-laps not less than 6 inches. Mop hot coal-tar pitchat the rate of 25 pounds per 200 square feet for the

not touch felt in any place. Mop the top surface ofthe top layer with hot pitch at the rate of 25 poundsper 100 square feet. As far as practicable, extendthe waterproofing up vertical surfaces not less than8 inches. If asphalt felts and moppings are used,coat the concrete with asphalt primer conformingto Federal Specifications SS-A-701, at the rate of1 gallon of primer per 100 square feet. Allowprimer to dry and then apply hot asphalt at the rateof 30 pounds per 100 square feet. Lay either two orfour layers of asphalt-saturated felt conforming toFederal Specification HH-R-590, Type I (alsoASTM D-173 cotton-fabric felt, ASTM D-1327burlap-fabric felt, ASTM D-1668 glass-fabric felt),as recommended for coal-tar pitch felts except thatmoppings should be at the rate of 20 pounds per100 square feet, using asphalt that conforms toFederal Specification SS-A-666.

6.3.7.3 Concrete Topping over WaterproofingWhen bituminous-membrane waterproofing is ap-plied, a 3-inch concrete topping should be providedover the waterproofing. A 2-inch concrete toppingshould be provided over metallic-typewaterproofing. Topping should be applied asrecommended for resurfacing in paragraph 6.3.4.Extreme care should be exercised to preventdamage to the waterproofing membrane.6.3.8 Surface Treatment

6.3.8.1 Selection. The application of a surfacetreatment that tends to increase the density andprotect the wearing surfaces of concrete is usuallydesirable. The selection of the surface treatmentshould be governed by the nature of the operationsnormally conducted on the floor. The selection,preparation, and application of surface treatmentsare covered in detail in paragraph 2.2.13 of thismanual.

6.3.9 Reconditioning Concrete Floors toReceive Coverings

6.3.9.1 General. Coverings are primarily used onfaulty wood floors. However, occasions may arisewhen it is necessary to lay coverings over new orold concrete floors. In such cases, the followingprocedures are recommended.6.3.9.2 Preparation of Concrete Floors. To besuitable for covering, concrete floor surfaces mustbe smooth, fully cured, dry and free of oil, grease,dirt, lime coating, and other substances that willprevent proper bonding between floor and cover-ing. Score with a wire brush. A single coat of paintthat is dry and well bonded to the concrete may beremoved. Where there are two or more coats ofpaint, varnish or other finishes, or where there is


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scaling and looseness, remove all coats by one or dryness of floors is in doubt, one or more of themore of the methods described for cleaning wood following tests should be performed:floors.6.3.9.3 Roughness. Old concrete floors that arerough, spalled, rutted, cracked, or in otherwise un-satisfactory condition, must be repaired beforelaying a flexible floor covering. Frequent repairs orreplacements are necessary when coverings are laidover deteriorated floors, especially those subjectedto wheeled traffic. Use complete concrete patches,cement grout, quick-set patching cement, crackfiller, or other suitable materials and methods, toobtain a smooth surface. See chapter 2 for detailson concrete-slab repairs. If the concrete floor is insuch condition that patching is impracticable, atrowel-on type of underlay should be installed.

each putty ring and cover with a piece of flat glass,6.3.9.4 Alkalinity. Concrete floors are usually al-kaline and may be coated with free lime. This canbe detected by applying a 1-percent solution ofphenolphthalein in alcohol (obtainable at anydrugstore) to the concrete surface. Dampen severalspots on the concrete with water and apply a fewscattered drops of the phenophthalein. If the con-crete is alkaline, the drops will turn red or purple.Test the suspected floor at several points. Floorsshown to be alkaline and floors on which strongcaustics or alkali solutions have been used toremove paint, varnish and similar materials areneutralized by washing with a 10-percent solutionof muriatic acid and water. Rinse the floor toremove acid and lime. Allow enough time to drythoroughly before applying the covering cement.6.3.9.5 Dampness. All types of flexible floorcovering can be laid over suspended concrete floorswhich have underfloor ventilation. Allow sufficienttime (2 or 3 months may be required, depending onthe weather) for a new floor to dry before coveringis applied. Open windows for natural ventilationduring daytime, but close them at night to shut outdamp air. Concrete with a hand-troweled surfacetreated with a hardener also dries slowly. If boxes,mats, or other objects with large flat-bottomsurfaces have been on the concrete floor for a longtime, they should be moved and the area inspectedfor wet spots, which indicate that moisture may becoming up through the concrete. This moisture isusually not seen on exposed areas because itevaporates as fast as it reaches the surface. When

a. Flat Sheet Test. Place pieces of flat glass,rubber, or other waterproof sheets at several pointson the floor. Remove the covering after about 24hours. It may be assumed that the floor is dry if nomoisture shows on the concrete. If moisture shows,allow additional time and apply heat and ventilationto assist in drying.

b. Putty Ring Test. Form rings of putty about6 inches in diameter and ½ inch high at severalpoints on the concrete. Inside each ring drill one ortwo ¼- to ½-inch-diameter holes about 1 inchdeep. These holes will allow any moisture in theslab to escape. Place a level teaspoonful of granu-lated, anhydrous calcium chloride in a small dish in

pressing the glass down on the putty to keep out alloutside air. If the floor is damp, beads of moisturewill appear on the glass cover in 24 to 48 hours andthe calcium chloride will be partly or completelydissolved. If dampness is noticeable, repeat the testat weekly intervals until the calcium chloride doesnot dissolve.

c. Adhesive Patch Test. Spread patches ofadhesive about 2 inches square in each corner andat several spots elsewhere on the floor. After 24hours, test the adherence of adhesive with a puttyknife. If the adhesive peals off, moisture is risingtoo rapidly for a satisfactory installation of any ce-mented-on covering. Allow additional time fordrying.6.3.9.6 Preparation of Floor for Rug or CarpetCoverings. Concrete floors that are to be coveredwith carpets or rugs should be sealed to preventdamage from the dust that seeps through the cov-erings. Prepare the floor by the following process:

a. Thoroughly clean the floor, exposing thetrue wearing surface so as to disclose any defects.Patch honeycombed areas and fill cracks withmastic.

b. Apply proper surface treatment as describedunder the applicable portions of paragraph 2.2.13.

c. If nailing strips for fastening the carpet tothe floor were not installed when the floor was con-structed, provide suitable fasteners in the concretesurface.

SECTION IV—TERRAZZO FLOORS

6.4.1 General chips in a matrix of portland cement or, more

Terrazzo traditionally has been a form of mosaicflooring made by embedding small pieces of marblein mortar and polishing. Today, this traditionalmaterial is obtained by combining selected marble

recently, in synthetics or resinous matrices.

6.4.1.1 Cementitious Terrazzo. Generally, cementi-tious terrazzo is a mixture of marble chips andportland cement. These terrazzo floors are usually


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laid on concrete slabs and may or may not be including the regular application of a sealer. Sealingbonded directly to the concrete. When structural of new terrazzo prolongs the slow-drying processmovement or vibration is anticipated, a "floating" of the cement, making the floor denser and assuringterrazzo floor is usually installed. The concrete slab longer life. The use of a sealer on old terrazzois overlaid with a layer of sand, which is covered retards the penetration of stain-carrying water intowith a waterproof membrane such as bituminous the marble and cement mixture. Sealing alsofelt, and a cement mortar underbed is installed on prevents dusting and blooming.the felt. The finished terrazzo surface, e to ¾ inchthick, is then laid over the underbed. The totalthickness of underbed and terrazzo surface is 6.4.3 Discoloration of Terrazzousually 2 to 3 inches. To guard against furthercracking, terrazzo areas are limited to 4 by 4 feet,with dividing strips of nonferrous metal set in themortar bed and extending to floor level. Terrazzofloors may be bonded to the concrete without sandor felt between or may be integral with theprepared slab.

6.4.1.2 Installation of Topping After the underbedhas hardened sufficiently, the terrazzo is laid andthen compacted with heavy rollers. The wearingsurface is ground and polished after it hashardened.

6.4.1.3 Resinous (Thin-Set Terrazzo). This nonce-mentitious type of surface is made by embeddingmarble chips in a matrix of resin such as epoxy,polyester, latex, or polyacrylate. Latex terrazzomay be as thin as d inch while the others may be asthin as ¼ inch.6.4.2 Cleaning New Floors

Terrazzo appears to be dense and very hard, butthe cement is sensitive to harsh soaps and cleaners,which can cause the floor to be pitted, rough, andpermanently susceptible to dusting and trapping ofdirt. Sweeping compounds containing oil willpenetrate and permanently discolor terrazzo. Newlyinstalled floors should be scrubbed with a syntheticdetergent cleaner two or three times a week andmopped on alternate days. The floor should berinsed thoroughly after each washing. After 2 or 3months of this treatment, the floor will acquire anatural sheen and require only routine maintenance,

When areas of a terrazzo floor become yellowwhile adjacent slabs retain their original color, thediscoloration is generally due to the way the floorwas originally finished. Poulticing with grit scrub-bing powders will remove most discolorationcaused by improper finishing. The powders shouldbe stirred slowly into a pail of hot water until athick paste of mortar consistency is obtained. Dis-coloration can also be removed by scrubbing thesurface with Javell water. Javell water is a strongbleaching material and should not be used for gen-eral-purpose cleaning. If not available from stock,Javell water may be prepared and applied to thefloor as follows: Dissolve 3 pounds of washingsoda in 1 gallon of water. Mix 12 ounces ofchlorinated lime and water to a paste in a shallow,enameled pan, adding the water slowly andmashing the lumps. Add the paste to the sodasolution making a maximum of 2 gallons by addingwater, and place the mixture in a coveredstoneware jar to settle. Use the clear liquid, dilutingit with six times its volume of clear water. Rinse thesurface with clear water and then use the Javellwater as a soap or scrubbing solution.6.4.4 Repairs

Repairs to a terrazzo floor should be made in ac-cordance with the specification for new floors.Only floor specialists who are capable of the classof workmanship necessary should be entrusted withthe work.

SECTION V—MAGNESIUM OXYCHLORIDE FLOORS

6.5.1 Installation and Repairs wheels. If magnesium-oxychloride floors are

Experienced personnel are essential in installing andrepairing magnesium-oxychloride (often calledMagnesite) flooring and the manufacturer’s recom-mendations should be followed closely. Floor fail-ures are usually caused by improper installation oruse. This type of floor is not recommended forkitchens, bakeries, warehouses, and other buildings 6.5.1.1 Specifications. The following table listswhere floors are subject to spillage of food, oil, specifications prepared by the American Nationalgrease, and considerable amounts of water or areas Standards Institute Association. See table 6-2.subject to the abrasive and shock action of truck They are offered as a guide to the many

mopped dry after each wetting, they will withstanddaily scrubbing. The flooring can be installed overprepared wood and concrete floors in thickness of¾ inch or more as conditions require. It shouldnever be applied over asphalt tile, linoleum, cork,rubber, or other flexible coverings.


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requirements that must be observed in mixing and varying size and color and a matrix of contrastinglaying oxychloride-type flooring. color.

Table 6-2. — Specifications Prepared By AmericanStandards Institute Association.

ANSI designations Title

A88. 1 . . . . . . . . . . Preparation of subfloors for Oxy-chloride-Composition Flooring.

A88.2 . . . . . . . . . . . General Purpose, Oxychloride-Com-position Flooring and Its Installation.

A88.3 . . . . . . . . . . . Heavy Duty, Oxychloride-Composi-tion Flooring and Its Installation.

A88.4 . . . . . . . . . . . Basecoat, Oxychloride-CompositionFlooring.

A88.5 . . . . . . . . . . . Nonslip, Oxychloride-CompositionFlooring and Its Installation.

A88.6 . . . . . . . . . . . Terrazzo, Oxychloride-CompositionFlooring and Its Installation.

A88.7 . . . . . . . . . . . Industrial Granolithic, Oxychloride-Composition Flooring and Its In-stallation.

A88.8 . . . . . . . . . . . Oxycement Underlay and Its Instal-lation.

6.5.1.2 General-Purpose Type (A 88.2). General-purpose type, most commonly used, is usuallymixed and laid in a solid color through the fullthickness of about ½ inch. This general-purposeflooring, when troweled to a dense, smooth, semig-lossy wearing surface, results in a floor with awearing hardness only slightly less than that ofTennessee pink marble.

6.5.1.3 Heavy Duty (A 88.3). Hard, coarseaggregates give a wearing surface suitable forheavier service required in light industrial plantsand other areas subjected to hard usage. Thisflooring is generally laid to a thickness of not lessthan ½ inch.

6.5.1.4 Industrial Granolithic (A 88.7). This is aterrazzo type since the aggregate is crushed gran-ite, trap rock or similar hard stone chips. This floor,usually laid to a thickness of ¾ inch, is finished bymechanical grinding but not such as will produce apolished surface. The finished floor is extremelytough and durable and will meet the demands ofextra hard usage.6.5.1.5 Nonslip (A 88.5). This flooring is furnishedin two types: Type I, General Purpose Nonslip, andType II, Heavy Duty Nonslip. Crushed rock is replaced in part with an abrasive aggregate toproduce a nonslip surface. Other types of oxychlo-ride flooring may be made nonslip by use of abra-sive materials in the wearing surface.6.5.1.6 Terrazzo (A 88.6) Oxychloride terrazzo isproduced by the use of marble or other chips of

6.5.1.7 Preparation of Subfloors (A 88.1). Thisspecification describes the preparation of new andold concrete, wood, brick, stone, metal and ceramictile subfloors prior to the application of an oxy-chloride floor.

6.5.2 Materials

Refer to manufacturer's standard specification forinformation relative to dry-mix compositions, ag-gregates, gaging solutions, water, metal anchoringmediums, liquid bonding mediums, division strips,and other components necessary to insure a propercementitious flooring installation.

6.5.3 Miscellaneous Requirements

6.5.3.1 Preparation. Prior to the start of any floor-ing operations, all pipe rails, radiators, space heat-ers, water coolers, and other items of equipmentthat will interfere with the installation of the floorshould be disconnected and removed from thework area. Check the present floor framing to seethat it is of such design, structural strength, andrigidity to withstand, without appreciable deflectionor movement, the maximum service to which thefinished floor will be subjected. When resetting theremoved equipment, necessary provision must bemade in all connections to accommodate the in-creased thickness of the new flooring.

6.5.3.2 Insulation. All new and existing pipeswhich will pass through the floor should be sepa-rated from the flooring by being wrapped with atleast two turns of asphalt-saturated felt leavingsufficient clearance to permit free movement of thepipe. Trim the insulating felt flush with the finishedflooring. Retard the possible passage of smoke orfumes by loosely packing the space be tweenflooring and pipe with glass wool, rock wool orother fire-resistant material. Metal surfaces, such asknothole covers, which will be in contact with thecomposition flooring should be given a coating ofbituminous paint.

6.5.3.3 Fitting Doors. Doors which swing over thenew flooring should be removed and sufficient ma-terial cut from the bottom edge to provide about¼-inch clearance. The cut edges should be given acoat of spar varnish or paint before the doors arerehung.

6.5.3.4 Thresholds. Thresholds of hardwoodshould be provided at all interior and exteriordoors. Thresholds will have a vertical surface abut-ting the new flooring and a 30E bevel on the exteri-or.


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6.5.3.5 Temperature. In areas where composition the wood floor may be used in lieu of the felt offlooring is to be laid, the room temperature should paper. A mechanical anchoring medium consistingnot exceed 95E F (35E C) until final set is attained. of meta lath or metal mesh should be laid over theThe temperature at time of installation should be fel with lapped and wired edges so as to covermaintained substantially uniform and should not completely the surface which is to receive thedecrease more than 20E F (-6.7E C) for at least 24 flooring mix. The anchoring medium should behours after completion of the floor. Composition secured by means of nails and staples, placed aboutfloorings should not be laid when the work-area 6 inches apart in two directions. The fasteningstemperature is less than 50E F (10E C). Heating should be driven in such a manner that theshould not be accomplished by means of salaman- anchoring medium is nowhere embedded in the feltders. Warm air should not be blown across freshly and Sc that a gage [1/18] inch thick will just fitlaid composition flooring. During the installation between the felt and the anchoring medium. Nailsand curing period, doors and windows to the work should extend through not less than seven-eighthsarea should be kept closed or so arranged as to of the wood floor's thickness and in case of aprevent harmful circulation of air. double floor should extend into the lower layer.

6.5.3.6 Additional Requirements. Check the man- 6.5.4.3 Base. Where wood-stud walls to receive aufacturer's standard specification relative to the composition base adjoin an existing wood floor, thefloor to be laid for additional installation require- felt and metal lath on the floor should be turned upments. the walls to within ½ inch of the top of the base

6.5.4 Preparation of Surfaces

Subfloors of both wood and concrete should be dryand thoroughly cleaned free of mud, grease, wax,plaster, paint, asphalt and any other foreign substances.

6.5.4.1 Concrete Subfloors. The term concrete in-cludes lightweight concrete, cinder concrete, andconcrete fill or grout. The surface glaze should becompletely removed by sandblasting,bushhammering, or other manner approved by theinstallation engineer. In addition to removing theglaze, the floor should be adequately roughened. Ifa bush-hammer is used, not less than 70 percent ofthe surface should be roughened, with the hammermarks distributed uniformly. If a pick is used, thepickmarks should be not less than c inch deep, notless than 2 inches in diameter, and be evenly spacedat intervals not exceeding 6 inches on centers.Rapid scarifying may be accomplished by use of apower-driven machine equipped with a cylindricalcage fitted with a series of hardened steel cutters.The cutters are mounted to provide a flailing,scoring hammermill action which results in adiagonal or crosslatched pattern in the concretesurface. Cracks in old concrete should be cut outsufficiently to permit removal of loose chips anddust and then grouted flush.

6.5.4.2 Wood Subfloors. Place on the cleaned gasoline, turpentine, animal, mineral and vegetablewood floor a covering of 15-pound, asphalt- oils, and greases. However, good housekeepingsaturated felt or an equivalent waterproof building and safety require speedy removal of these materi-paper. Lay the felt or paper free of wrinkles or als when spilled on the floor. The use of a solventbulges and with all edges lapped not less than 1 to remove oil and grease usually will not harm theinch. A coating of emulsified asphalt of such floor though it may remove the easily replaced waxconsistency that it will not pass through cracks in coat.

and be secured by nailing into the studs andbacking. Where wood-stud walls to receive compo-sition base adjoin an existing concrete floor, thewalls should be covered with a strip of asphalt feltand metal lath to about base height. Bend the striplath to about base height. Bend the strip lath to lap2 inches onto the concrete floor and secure withconcrete stub nails spaced about 6 inches apart.Secure top edge of metal lath by nailing into thestuds and backing.

6.5.4.4 Flashing Areas subject to water spillagewhich are situated on upper floors should be pro-vided with adequate perimeter flashing to preventleakage to space below.

6.5.4.5 Installation Procedures. Refer to manufac-turer's standard specifications for information rel-ative to slump test, applied thickness, placing thecomposition mix, troweling, curing, sealing, andprotection.

6.5.5 Cleaning

The finished floor should not be scrubbed or flood-ed with water for at least 15 days after installation.Where tests for electrical conductivity are required,they should not be made until the floor hascompletely cured, usually a period of 30 to 60 days.Properly formulated composition floors, whencured and sealed, offer considerable resistance to


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SECTION VI—CLAY TILE FLOORS

6.6.1 Ceramic Tile surrounding title and place the setting mortar mixed

Ceramic tile is glazed or unglazed, manufacture insmall squares, hexagonal, rectangular, and circularshapes about 'A inch thick, and is often arranged inmosaic patterns. The pieces are usually factory-assembled on paper sheets in the required pattern,laid on a mortar setting bed, pressed firmly on themortar, and tamped true and even with the finishedfloor line. Grout is then force( into the joints, fillingthem completely, and is finished flush and levelwith the floor line.

6.6.2 Quarry Tile

Quarry tile is unglazed and manufactured in squareand rectangular shapes, ranging from 2-3¾ to 9inches wide, and 2-¾ to 12 inches long, withvarying thicknesses. Tiles are laid individually or amortar setting bed with joints about ½ inch wide.

6.6.3 Repair of Tile Floors

Replace broken or badly stained tiles and resetloose tiles in the following manner:

6.6.3.1 Remove the damaged or loose tiles.

6.6.3.2 Clean the mortar from the edges of thesurrounding tile.

6.6.3.3. Roughen the concrete underbed toprovide a good bond for the new setting cement.

6.6.3.4 Dampen the underbed and edges of the

in the proportion of 1 part portland cement to 3parts sand.

6.6.3.5 Set the tile, tamping it to the level of thefinished floor.

6.6.3.6 Fill the joints with grout or pointingmortar, matching the color and finish of the jointsof the original floor as closely as practicable. If themortar in the existing joints has deteriorated,cracked, or crumbled, thoroughly clean the joints ofall loose mortar and repoint them with grout orpointing mortar. Grout joints c inch or less widewith neat portland cement grout of the consistencyof thick cream. Point joints c to ¼ inch wide withpointing mortar consisting of 1 part portlandcement to 1 part pointing sand. Point joints widerthan ¼ inch with pointing mortar consisting of 1part portland cement to 2 parts pointing sand.

6.6.3.7 In locations such as food preparationareas, where the floor is directly exposed to theeffects of corrosion agents, use acid-resistant jointmaterial to fill the joints. The acid-resistant mortarsare proprietary products and should be mixed inaccordance with the manufacturer'srecommendations. They are composed of bothpowdered and liquid resin cement and should beresistant to the effects of oils, fats, greases, organicand inorganic acids, salts, alkalies, and mineralsolvents.

SECTION VII—MASTIC FLOORS

6.7.1 Description and Use grease can be removed with a solution of ¼ pound

Mastic coatings applied on concrete or rigid woodfloors provide a resilient floor finish that is suitablefor a variety of uses. Mastic topping, when hardand cured, forms a tough, dustless flooring that ishighly resistant to abrasion and shock fromvehicles. Neoprene-type coating similar to thatused in mothballing equipment can be obtained ina variety of colors and makes an excellent resilientfloor finish. The mastic topping should be finishedto a thickness of not less than ¼ inch above thehighest section of existing floor, with additionalthickness as required. Free edges should be feath-ered.

6.7.2 Preparation of Floor

The concrete floor to be topped should be cleanedof all dust, dirt, and other foreign matter by vigor-ous sweeping, airblasting (operators must wearsafety glasses), or other suitable means. Oil or

of common household lye or trisodium phosphatedissolved in 1 gallon of hot water. The hot solutionshould be applied to the greasy surface and allowedto remain for about 10 minutes. Then the areashould be scrubbed with a stiff bristle, fiber, or wirebrush. The area should be mopped, flushed withclean water, and mopped again. This action shouldbe repeated until all the cleaning compound isremoved. Care must be exercised to keep thecleaning compound away from skin and eyes. Afterthe concrete has been cleaned and is still damp, aspecially prepared emulsified asphalt primer isapplied and allowed to dry to a tacky state. Then,the floor is topped with either cold or hot mastic.

6.7.3 Cold-Laid Mastic

Cold-laid bituminous mastic floors are usually laidin layers. Coatings consist of a fibrous mastic. Themastic material is similar to the primer but isground with enough asbestos and finely powered


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siliceous material fillers to make a very thick, pasty, the mixtures used in sheet asphaltic pavements, butfibrous mass. When a coating is dry, succeeding they contain more asphaltic binder so that they canthin coats are applied until the desired thickness is be troweled into place when heated to a fluidobtained. The total thickness of cold-laid mastic condition. The mastic is usually applied in layers ¾floors is usually ¼ to d inch. inch or more thick. The mastics used should be

6.7.4 Hot-Applied Mastic

Hot-applied bituminous mastic floors are similar to

applied according to the manufacturer'srecommendations.

SECTION VIII—CONDUCTIVE FLOORS

6.8.1 Description and Use

Conductive floors made of terrazzo or other suita-ble materials are required to prevent accumulationof electrostatic charges. Conductive floors are usedin hospital and dispensary operating and deliverysuites where explosive anesthetics are used, inammunition inspection and manufacturing areas,and in areas where electrical equipment is tested.6.8.2 Testing

Conductive tests should comply with requirementsin the National Fire Protection Association Stand-ard, Recommended Safe Practice for HospitalOperating Rooms, which prescribes the method ofinstallation. The floor should be tested forconductivity immediately before the first use.6.8.2.1 Schedule. The following schedule isrecommended for subsequent testing of hospitaloperating rooms.

a. Test at least once a month.b. Test after each alteration or repair of the

floor.c. Test after each waxing has dried and again

about 24 hours after the waxing.

MO-125, AFM 91-2)6.8.2.2 Conditions. Make the tests only under thefollowing conditions:

a. When the room is free of explosive gas mix-tures.

b. When the floor is completely dry, i.e., atleast 4 hours after cleaning or waxing.

c. When the relative humidity of air in theroom is the same, or as close as possible, to that atthe operating level (55 to 60 percent, whencontrollable).6.8.3 Repairs

Conductive floor repairs should be accomplished bymatching the existing material and workmanship asclosely as practicable, following the floormanufacturer's recommendations. A test for con-ductivity must always be made after the repair hasbeen completed. (See paragraph 6.8.2 for testprocedure.)6.8.4 Maintenance

Conductivity floors must be both sanitary and con-ductive. Improper cleaning methods that allow afilm to cover the floor, thereby prevent conductivi-ty, will render the floor useless in preventing ex-plosions from static electricity. Custodial servicesare discussed in the Tri-Services Manual, "MilitaryCustodial Services Manual" (TM 5-609, NAVFAC

SECTION IX—RESILIENT FLOOR COVERINGS

6.9.1 General dragged across resilient floors. Suitable rests

Resilient floor coverings generally used include li-noleum, vinyl plastic tile, vinyl asbestos tile, asphalttile, cork tile, and rubber tile. Floor coveringsshould be selected carefully and laid according tothe manufacturer's recommendations. If felt liningis necessary, it is cemented to the floor, and theresilient covering is bonded to the felt. In othercases, the covering may be bonded directly to thefloor. Any cement paste or primer used directly onthe floor should effectively seal the pores in thefloor.

caster should revolve freely. Most flexible floor6.9.2 Protection of Coverings

Heavy furniture or equipment should not be

should be provided on furniture and equipmentsuch as lockers, files, and cots to distribute theweight when such objects are placed permanentlyon the floor. The maximum static load limit persquare inch for asphalt tile is approximately 25pounds; for cork tile, 40 pounds for compositiontile, 50 pounds for linoleum, 75 pounds; and forrubber tile, 200 pounds. Chairs, desks, and othermovable equipment should be fitted with flat-facedgliders not less than 1 ½ -inches in diameter. Chair-roller, wheels or casters should be at least 2 inchesin diameter and have a ¾-inch-wide face; the whole

coverings are designed for interior use and should


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not be installed where they are exposed regularly to grooved underlayment nails placed 6 inches onsun and rain, extremes in temperature, hot water or center at the edges and 12 inches on center in thesteam, and damaging solvents, greases, and oils. middle of the sheet. Nails should be driven flush

6.9.3 Care of Installed Equipment

Before covering is laid, all pipe rails, radiators,space heaters, water coolers, and other equipmentthat will interfere with installation of the coveringshould be disconnected and removed from thework area. When the equipment is reset, necessaryprovisions should be made in all connections to ac-commodate the increased thickness of the floor.Pipe passing through the flooring should bewrapped with at least two turns of asphalt-saturat-ed felt and the space between pipe and flooringloosely packed with glass wool or similar fire-re-sistant material.6.9.4 Adhesives

Adhesives for use with felt- or fabric-backed flexi-ble floor coverings should conform to the floor-covering manufacturer's recommendations. Underdry conditions, most linoleum pastes show highadhesive strength, but few have sufficient resistanceto moisture to suitably bond floor coverings tosubfloors in humid locations. Lignin paste issuitable for bonding linoleum and felt-backedmaterials in dry locations only. Cumar resin andresin-oil cements show fair resistance to moisture.Cements and primers for use above grade floorswith asphalt-saturated flexible floor coveringsshould be of the asphalt-emulsion type or asrecommended by the floor-covering manufacturer.6.9.5 Underlayments on Wood Floors

Lining felts and floor coverings may be applied di-rectly to wood floors providing there are no cracksor ridges. Otherwise, plywood, hardboard, or otherunderlayment may be required.6.9.5.1 Rigid and Semirigid Board Types.Plywood should be laid face side up to receive thefinish floor. It should be three-ply sheathing gradeconforming to commercial standard CS 45-55 andbe a minimum of ¼ inch thick with exterior glue.Increased thickness may be necessary, dependingon the structural adequacy of the subfloor or toachieve uniform alignment with adjacent existingfinish floors. Whenever possible, plywood shouldbe laid so that the face plies are at a right angle tothe wood subfloor. When the subflooring is laid di-agonally, the face plies should be laid at a rightangle to the joist or sleepers. Hardboard is less de-sirable as underlayment than plywood. If used, itshould be laid with the back or rough side up, toreceive the bonding paste. Plywood and hardboardunderlayment should be face-nailed to the existingfloor, with 1¼-inch hardened screw-type or ring-

with the surface of the board. Staples should neverbe used as underlayment fasteners.6.9.5.2 Troweled on Types. When using underlay-ments of the troweled-on type, follow the manufac-turer's recommendations for mixing, application,and curing.6.9.6 Crack Fillers for Wood Floors

All holes or cracks in wood floors or underlay-ments should be filled with a suitable crack fillerbefore flexible coverings are laid. Crack fillersshould adhere tightly to crack surfaces, have mini-mum shrinkage, and resist crumbling or powderingunder traffic. Factory-prepared commercial fillersshould be applied according to the manufacturer'srecommendations. Job-mixed fillers are composedof 90 parts fine sawdust and 10 parts a fast-dryingorganic vehicle, such as lacquer, shellac, or anapproved commercial shellac substitute. Filler ismade by adding the vehicle to the sawdust until amedium-stiff, easily worked paste is obtained. Onlythe amount that can be used in approximately 80minutes should be mixed at one time. The fillershould be worked into holes and cracks, smoothedoff flush with the surface of the floor orunderlayment, and allowed to dry for at least 1hour before the floor covering is laid.6.9.7 Vinyl Sheet Flooring

6.9.7.1 Vinyl sheet flooring is available in a widevariety of product characteristics including color,texture, and resilience. They may be used in a va-riety of environments based on the thickness ofwear layer and conditions of the floor structure.Flooring should conform to Federal SpecificationsL-F-475 or L-F-1641. Installation practices andmaintenance as specified by the manufacturershould be followed in all cases.6.9.7.2 Job Preparation.

a. Job Inventory. The room should bemeasured wall to wall in at least two locations eachfor length and width, making allowances for door-ways. An additional 3 inches should be included ineach measurement. When more than one width ofmaterial is to be used, an additional allowance of 3inches is required per run for fitting the first andsuccessive sheets. Length allowance must considerpattern repeat characteristics of the flooring. Someflooring patterns require sheet reversal at the seamswhich must be considered prior to cutting.

b. Removing Old Sheet Flooring. CAUTION:Most sheet vinyl floorings contain asbestos or otherinert fibers which may cause serious bodily harm.


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Do not remove backing or lining felt by sanding or c. Bonding. Adhesives will be specified by thegrinding or any method which will create dust. floor covering manufacturer based on type ofHave a sample of the old sheet flooring tested for subfloor or underlayment and floor coveringasbestos. If asbestos is present, special removal material. Adhesives should be warmed at 70E F forprocedures will be required. If the existing floor 48 hours prior to installation and should be appliedcovering is well bonded, several products may be using a notched trowel.laid directly on the existing surface. If removal isrequired, the recommended method is to cut thewear layer into narrow strips of 4 to 18 incheswide, depending on the product. The covering maybe split from the backing and pulled at a sharpangle or core-rolled. The remaining felt willnormally have a surface smooth enough to acceptthe new floor. Removal of the felt backing must bedone in strict compliance with the manufacturers'recommended procedures.

6.9.7.3 Installation. Sheet flooring containing as-bestos should not be used. Sheet flooring may beapplied to either concrete or wood floors undercertain conditions. Both types of floors must befree of moisture at all times or the floor coveringmay warp or become damaged.

a. Concrete floors. Concrete subfloors on orbelow grade must be tested for moisture. The floorshould be cleaned by thorough sweeping with awire brush to remove all loose particles, followedby priming or sizing in accordance with the manu-facturer's recommendations. The floor may betested for moisture by installing small panelsthroughout the floor area. This test should includeareas of the subfloor which are least subjected todrying conditions. If the panels are securely bondedafter 72 hours, it may be concluded that the floorsurface is dry and sufficiently clean of foreignparticles to permit installation. All holes, cracks,and joints in subfloors must be filled using productsrecommended by the manufacturer of the floorcovering. Prior to installation, the floor should beswept or vacuumed clean of all dirt and debris.

b. Loose-Lay of Floor Covering. If only onewidth of flooring is to be installed, it should beunrolled and layed out and marked with the roomdiagram using a wax pencil. Allowance for excessmaterial (1½ inches per side) must be considered.The covering can then be cut using a utility knife tothe oversized dimensions of the room andtransported to the room. It is a good practice toallow the covering to lay full unrolled, flat on thefloor, in a warm room (70E F) or (21E C) for about24 hours before cementing it into place. Thecovering can be trimmed with a utility knife. Doorjambs and corners must be trimmed carefully toavoid miscuts which may be exposed or provide apoor fit.

d. Seams. If seams are required, advance plan-ning must avoid placing a seam within 6 inches ofjoints in the underlayment. After the first sheet isflattened to the floor, the second sheet should beoverlapped so that the design matches exactly. Thesheets should be taped together to avoid slippage.A scrap piece may be laid under the overlappingpieces to provide a better fit and to allow a bettercut of the lower sheet without damaging the un-derlayment. The cut should be made using asharpened blade and metal straightedge throughboth layers of the overlap. The knife must be keptstraight to avoid a beveled edge which cannot besealed properly. The sheets may then be foldedback and the adhesive applied to the underlayment.Insure that no excess adhesive is left which mayooze up into the seam. The flooring should berolled into the adhesive using a weighted roller.

e. Seam Sealing .Use seam sealersrecommended by the manufacturer only. Insert thevertical metal fin of the seam sealer applicator intothe joint at one end of the seam and apply very lightpressure to lay out a bead of sealer. The sealer willweld the vinyl core and the wear layer. Care shouldbe exercised to avoid spilling the seam sealer. Ifthis happens, no attempt should be made to removeit. Seams should not be disturbed for 24 hours aftercompletion to allow welding process to becomplete.6.9.8 Asphalt Floor Tile

6.9.8.1 General. Asphalt flooring tile is suitablefor installation on most wood and concretesubfloors above grade and concrete floors incontact with the ground. Asphalt-tile is made of ablended composition of asphaltic or resinousbinders, asbestos fibers, plus insert fillers orpigments, formed and cut to size under heat andpressure. This material is one of the few resilientfloor coverings that can be used to advantage onconcrete slabs on ground where some resistance tomoisture is necessary. Asphalt tile, available inmany plain and marbelized colors, not only presentsan attractive appearance but offers other importantadvantages. It is quiet, comfortable, safe to walkon, extremely durable, and highly resistant toabrasive action of foot traffic and common abusessuch as scuffing and cigarette burns. It is anodorless, nonabsorbent covering which does notoriginate dust; it is easy to clean and has a low


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maintenance cost. All these factors make it are not always carried in stock. Several sizes inparticularly desirable for use when high sanitary octagon and hexagon shapes and half tiles forstandards must be maintained. When exceptional diagonal installations are available at extra cost.abuse or severe accident makes repair necessary, Asphalt tile is available in c- and / -inch thick-new units to replace the damaged ones can be ness, weighing approximately 1a and 2 pounds perinserted easily. square foot, respectively. The c-inch-thick tile is6.9.8.2 Characteristics of Asphalt Tile. Thefollowing are important characteristics of asphalttile:

a. Color Variations. Asphalt tile ismanufactured mainly by converting batches ofseveral raw materials into units of the finishedproduct. Due to the human element involved andvariances of raw materials, such a process naturallyresults in slight variations in tile colors. These colorvariations, which are characteristics of the product,are not noticeable in designs and patterns of two ormore colors. Differences in shade are generallynoticeable when floors are laid in solid colors.However, the effect can be minimized by mixingthe tile from several cartons as the tiles are applied.

b. Effect of Grease and Oil. Since asphaltsand asphaltic resins are soluble in oil and grease, itis obvious that ordinary asphalt tile is not adaptedfor use in kitchens, gas and oil stations, machineshops and adjacent office areas, behind meatmarket counters, or in mess halls.

c. Effect of Acids. Although asphalt tile hasconsiderable resistance to acid, it is destroyed byhigh concentrations and is not recommended foruse on floors exposed to strong acid solutions. Itmay be used satisfactorily in laboratories if spilledacids are normally removed immediately.

d. Effects of Temperature and Sunlight.Asphalt tile is not adapted to outdoor locationsexposed to the sun or to use on floors subjected tocontinued or intermittent extremes of cold andheat.

e. Effect of Moisture. Although asphalt tile isnot affected by the normal dampness in concreteslabs on ground or by moisture resulting fromnormal maintenance, it is not recommended forfloors constantly exposed to wet conditions. it isnot suitable for use in shower stalls or adjacentfloor areas or for open porches and other outsidelocations. Continued exposures to water impairsthe cement at joints, eventually shrinking the tile sothat it loosens from the subfloor.6.9.8.3 General-Purpose Asphalt Tile. General-purpose asphalt tile and base should conform torequirements of the Federal Specification SS-T-312. A preferred size is the standard 9 x 9 inches.Other available regular sizes are 12 x 12 and 18 x24 inches. Other sizes in square and rectangularshapes are made by one or more manufacturers but

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recommended for most installations. Straight andcove-bottom types of base are furnished in heightsof 4 and 6 inches. General-purpose asphalt tile isdivided into Groups A, B, C, and D, according tocolor and cost. Group A colors, plain and verydark, are most economical in cost. Group B, at aslight additional cost, covers the dark plain andmarbelized colors. Group D colors are light, plainand marbelized, and the most expensive. It shouldnot be inferred that the more expensive tile is ofbetter quality, but simply that because of specialpigments and resins the manufacturing cost of light-colored tile is greater than for dark-colored tile.Grease-resistant tile and base is obtainable in twoclasses: Class I, which is resistant to edible oil andalkali; and Class II, which is resistant to mineral oiland alkali. Class I is recommended for installationin dining spaces of mess halls and areas where oilspillage may occur. Grease-resistant tile is moreexpensive than any of the general-purpose tiles.6.9.8.4 Preparation of Sub/Floors. Refer topreceding paragraphs for descriptions of wood andconcrete floor preparation and the installation ofunderlayments.6.9.8.5. Lining Felt. Lining felt for applicationover new or reconditioned wood-strip floors shouldbe an asphalt-saturated asbestos fiber or rag felt ofa type made specially for use under asphalt tile. Adry felt is not satisfactory because it gives too softa cushion under the tile and permits excessive in-dentation of tile under loads of chairs and otherpieces of furniture. Also, a dry felt may split andcrawl when subjected to moving traffic. Proceduresfor laying felt are described in paragraph 6.9.7.3.1.Felt is not required when asphalt tile is laid overplywood, hardboard or smooth concrete.6.9.8.6 Adhesives. Use only adhesives approved bymanufacturer of the asphalt tile.

a. Linoleum Paste. Linoleum paste is used tosecure lining felt to wood-strip flooring.

b. Asphalt Base Primers. Primers for use onconcrete floors and mastic underlay shall be of thefollowing types:

(1) Emulsion-Type Primers. This primer isa homogeneous emulsified asphalt of suchconsistency that when mixed with water it caneasily be brushed to full coverage on the floor. Thistype of primer should be used only on suspendedconcrete floors that have heated or well-ventilatedspaces underneath.


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(2) Cutback-Type Primers. This primer is Some asphalt cements freeze at low temperatures.composed of an asphaltic base and a suitable light, When freezing occurs, thaw the cement in a warmvolatile solvent. Consistency should be such as to room for several days, keeping container tightlyafford easy brushing on the floor. This type primer closed. Stir thoroughly before using. Delivery ofis required on concrete subfloors on or below grade adhesives in the manufacturer's sealed containersand on new concrete subfloors which may contain with the labels intact and seals unbroken should beconcealed moisture. It is optional for use on sus- required.pended concrete subfloors which have heated orwell-ventilated spaces underneath.

facturer's printed recommendations. Tile is ce-c. Asphalt Base Cements. Asphalt cementsmade specifically for bedding and fastening asphalttile shall be of a heavy consistency which can beapplied and spread effectively with a standardtoothed trowel.

(1) Emulsion-Type Cement. This cement isa homogeneous emulsified asphalt suitable for usewithout the addition of other ingredients. See Fed-eral Specification MMM-A-1 15.

(2) Cutback-Type Cement. This cement iscomposed of an asphaltic base and suitable volatilesolvents. See Federal Specification MMM-A-110.

(3) Cove Base Cement. Cove base cementshould be a semi-waterproof type made specificallyfor use with asphalt tile.

6.9.8.7 Use of Asphalt Cements. Asphalt tile maybe secured to most types of subfloors with anemulsified asphalt cement. However, a moisture-resistant, cutback asphalt cement is always neces-sary for securing asphalt tile to concrete subfloorswhich rest directly on the ground. Asphalt cementsare used as adhesives and never in place ofunderlayments for smoothing rough surfaces. Toomuch adhesive is usually applied when attemptingto fasten asphalt tile over rough or unevensubfloors, and this results in "bleeding." In addition,the tile does not have sufficient contact with thesubfloor to make a satisfactory bond and eventuallyloosens. An excess amount of the cutback-typecement not only results in bleeding but preventsearly evaporation of the solvents. This may softenthe asphalt tile and lower its resistance to indenta-tion. Cutback cements must not be used with as-phalt-saturated felt or asphalt-type underlays, sincethe solvent in the cutback will be absorbed into anyasphaltic base and soften it. This causes theadhesive to lose its bonding effectiveness, and thetile may loosen and curl. The solvents in cutbackasphalt adhesives are flammable and volatile andmust not be exposed to open flame. Adequateventilation must be provided to take off fumes. Seethat fire extinguishers are conveniently located.Keep the asphalt cement containers tightly closedin storage as evaporation of solvent will cause thecement to become too thick for proper application.

6.9.8.8 Installation of Asphalt Tile. Installation ofasphalt tile should conform generally to the manu-

mented directly to cleaned and prepared concreteslab, plywood or hardboard underlay. Tile laid overwood-strip flooring is usually cemented to liningfelt previously cemented to the reconditionedflooring.

a. Layout. Before tile is laid, the floor areamust be squared and the best method of layingdetermined. This will depend on the shape of room,location of fixed furniture and doorways, and thetile design selected. Definite and specific instruc-tions that will apply in all cases cannot be given.Asphalt tile should be laid parallel to walls whichare at right angles in order to eliminate unnecessarycutting of the field tile and borders. Always start atthe center of the room and work toward the wallsso that border widths can be adjusted accordingly.

b. Temperature. Temperature of the cement,asphalt tile, room and subfloor must be maintainedat 70E to 80E F (21E to 26.7E C) for at least 24hours before and 24 hours after the laying process.Never apply cold tiles because condensation mayform on the underside and break down the bond ofthe cements. If any tiles are warped when removedfrom the shipping cartons, pile them on a flatsurface near a radiator or in a very warm room untilthey become flat. Adequate ventilation is importantbecause it hastens drying and maintains theadhesive properties of cement by preventingcondensation of moisture.

c. Spreading Cement. Stir the asphalt tilecement to uniform consistency in container. Spreadcement evenly over the floor ahead of tile laying,using a notched trowel. Allow the cement to dryfor approximately 30 minutes or until a tacky con-dition is produced before setting the tile. If tile isapplied too soon, the unevaporated solvent in cut-back cements may soften the tile, leading to possi-ble excessive indentation later. If the interval be-tween cement spreading and tile laying is too long,a poor bond will result.

d. Laying Asphalt Tile. When the cement hasbecome sufficiently dry, lay tile according to prede-termined design and layout. Field tile should be laidfirst. Cut and fit the border tile accurately against


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walls, built-in equipment, and other permanent laid. Prewaxing also protects the surface of tilesprojections and recesses. Lay so that joints fit against damage during transportation and instal-closely and form straight lines. Avoid squeezing the lation. However, even factory-waxed tiles must bejoints, as tile will expand and buckle with an protected if tile is laid before construction is com-increase in temperature. Embed each tile firmly to pleted. Cover tile floors with building paper, fabricprevent movement under traffic. When heated, as- or boards, especially at entrances and along trafficphalt tile can be cut with a linoleum knife or scored aisles.deeply to give a clean break. Apply heat slowly toback of tile to prevent blistering. Asphalt tilecutters are recommended for making straight cuts.A pin vice fitted with a steel phonograph needle isa convenient tool for scoring. Make a pencil markat each end of the piece to be cut, place astraightedge between the two marks, and score adeep scratch along the straightedge. Snap off thepiece of tile, making sure to start the pressure atone end of the scratched line rather than at thecenter of the piece. This method of cutting can bedone only with the grain, never diagonally or acrossthe grain. Exposed job-cut edges should besandpapered smooth.

e. Cove Base. The installation of a 4-inch-high buffed.cove base as part of the asphalt tile flooring may bedesirable. However, in areas where cove base issubject to frequent bumping by furniture or floor-furnishing equipment, rubber tile appears moredurable than asphalt tile. Vinyl cove base may alsobe used. Some base materials are furnished inprefabricated outside corners which are easy to in-stall and give a neat appearance to outside cornerwork. Instructions furnished by the manufacturer ofthe base material used should be followed in theselection of materials and fitting the base in place.

f. Removing Asphalt Cement Spots. If asphalt helpful in cutting holes for radiator leg bases. Whencement oozes up at joints or is smeared on tile sur- tile is laid over concrete, ball bearings can be usedfaces during the setting, scrap off immediately with for leg bases instead of the materials suggesteda putty knife and rub with a cloth saturated with a above. Heat asphalt tile and tap the ball bearingsmild neutral soap. If this does not remove all trace down with a hammer. In the event radiators haveof the cement, use 00 steel wool and a wet been set before tile is laid, raise the radiator, slidescouring powder, rinse off the clear water, and dry tile underneath, and place a heated ball bearingthe surface. under each leg. Weight and added heat of the

6.9.8.9 Finishing Improved appearance andlonger useful life will result if asphalt tile floor iscleaned and waxed before being put into use. 6.9.8.11 Tile on Stair Treads. Do not leave asphaltCleaning, especially wet washing, and waxing tile with unprotected edges on stair treads andshould be postponed untile tile has properly bonded landings. Suitable metal, plastic, or wood edgingsto subfloor or underlay. Should water or wax get must be fastened to the tread nosing to protect tileunder tile before cement has hardened, the bond edges and eliminate the tripping hazard. Do not usemay be destroyed and the tile will curl and break. edging strips which have concealed horizontalAs a precautionary measure, tile should not be flanges because the tile may crack at the rear edgecleaned or waxed for 2 weeks after setting. If floor of flange.must be used during this period, protect tile with acovering of paper, fabric, or wood walkways.

a. Prewaxing at Factory. Factory-waxed tiles should be given special attention before laying tile.eliminate the necessity of waxing after the tile is Asphalt tile floors should not be installed until

b. Initial Waxing Water-emulsion waxes, freefrom oils and volatile organic solvents and con-forming to Federal Specification P-W-155, aresafest for use on asphalt tile floors. Do not usepaste or liquid waxes containing solvents such asgasoline, benzine, turpentine, or oils. Such solventswill soften asphalt tile and cause the colors to run.Best results are obtained by initial application oftwo thin coats of water-emulsion wax. Allow ap-proximately 30 minutes for each coat to dry to ahard, medium-bright finish. Drying time depends toa large extent on room temperature, humidity andventilation. A higher gloss is produced by use of apower-driven buffer. Wax must be dry when

6.9.8.10 Radiators on Asphalt Tile. A radiator orother heavy fixture on legs should not be set di-rectly on asphalt tile. The weight of the radiator,together with the softening effect of heat, maycause the legs to sink into tile, resulting in bulgesand breaks. If tile is laid before the radiators areset, cut holes in the tile and insert a hard material toform bases for the legs. Ceramic tile, iron washers,or other metal disks of the same thickness as thetile make satisfactory bases. A piece of 1-inch pipe,ground on the outside to form a die punch, is

radiator will force the ball bearing down to theconcrete subfloor.

6.9.8.12 Precautions. Preparation of newsubfloors and the reconditioning of old subfloors


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other trades have completed their work. When 6.9.9.2 Recommended Installations. Vinyl-asbes-necessary to install the asphalt tile floor before tos tile may be installed over and above grade sub-other trades have completed their work, protect the floors directly or with a lining felt depending on thefinished floor with building paper or other suitable condition of the floor. Normally, a lining felt ismaterial. See that temperature of room and all used with strip flooring, and direct application ismaterials is maintained at 70E to 80E F (21E to used over plywood and hardboard. Vinyl-asbestos26.7E C) for 24 hours after installation. Install tile is not applied on or below grade subfloors. Theasphalt tile only over subfloors that are smooth, one exception is a concrete floor which has a mem-firm, and free from oil, grease, and other foreign brane waterproofing. Vinyl-asbestos can be bondedmatter. Do not lay asphalt tile over any resilient directly to metal or concrete stairs.floor such as cork tile, rubber tile, linoleum, or dryfelt. Asphalt tile should not be laid over a below-grade wood floor or one that is springy or hasloose boards. Legs of lockers, desks, cases, cotsand other items of furniture not subject to frequentmoving will be provided with suitable furnitureresets or wood blocks to prevent excessive 6.9.9.4 Installation of Tile. Conditioning the ma-indentation. Do not install asphalt tile where it will terials and work area and laying vinyl tile is ac-be exposed to excessive water, such as in open complished in much the same manner as describedporches, kitchens, dish-wash rooms, shower for asphalt tile in paragraph 6.9.8.8. Additionalcompartments and adjacent dressing spaces. Use specific recommendations of the vinyl tile manu-the type of adhesive recommended by the tile facturer relative to lining felt, adhesive, and in-manufacturer for each particular installation. stallation procedures will be followed closely.Directions for use of adhesives are usually on thelabels of the containers. Never use sweepingcompounds containing free oils, sand, or otherabrasives. Avoid as far as possible, the use ofgasoline, turpentine, benzine, and similar solventsas cleaning agents. Should it be necessary to useone or more of these materials, keep the room wellventilated, and see that no open flame is nearby.Use safe water-emulsion-type waxes. Do not usewaxes known to contain oils or other solvents. As-phalt tile in toilet rooms should not be waxed, es-pecially around urinals, as uric acid dissolves thewax and will leave a spotty appearance. Frequentdamp mopping is the best method of cleaning.Before using a new cleaner or wax on the asphalttile floor for the first time, moisten a white clothwith a material and rub over the surface of one ortwo tiles. If tile color shows on the cloth, a solventhas dissolved part of the tiles' surface and the ma-terial is not safe for use on asphalt tile. A safeprocedure is to get the advice of the asphalt tilemanufacturer before purchasing an unknowncleaner or polishing material.

6.9.9 Vinyl-Asbestos Floor Tile

6.9.9.1 Material. Vinyl-asbestos tile conforming tothe requirements of Federal Specification SS-T-312consists of thoroughly blended composition of athermoplastic binder, asbestos fibers, mineral fillers,and pigments. The binder consists of a PVC resinor a copolymer resin compounded with suitableplasticizers and stabilizers. Tile shall be 9 or 12inches square and c inch thick.

6.9.9.3 Preparation of Subfloors. Refer to the pre-ceding paragraphs and use vinyl manufacturer'srecommendations for descriptions of wood andconcrete subfloor preparation and the installation ofunderlayments.

6.9.9.5 Maintenance After Installation. Vinylfloor tiles are one of the easiest floors to maintain.After installation is completed, the floor will be al-lowed to set for 4 or 5 days before beginning main-tenance. This will allow the adhesive to set andbecome thoroughly hard. A sufficient first cleaningaction can be accomplished by use of lukewarmwater and a mild soap or other cleaner recom-mended by the tile manufacturer. Rinse with cleanwater and mop dry. Never leave any standingwater. If the floor has become badly soiled duringinstallation, it should be given a machine buffingwith 00 or 000 steel wool, after which steel woolparticles and dirt are removed by vacuum cleaneror soft broom sweeping. A machine buffing with asoft bristle brush immediately after the first washingor steel wool treatment should bring back theoriginal gloss. Initial waxing should be accom-plished when the floor is laid and cleaned. Afterinstallation is completed, allow at least 24 hoursbefore heavy furniture or other equipment is movedon the floor. The weight of fixed and movablefurniture and other equipment often causes in-dentations in resilient floor coverings. Legs ofchairs, desks, tables, etc., should be fitted withwide-diameter, flat-faced metal or compositiongliders or cups specially designed for the purpose.Where the design of the equipment does not permitthe use of gliders or cups, blocks of wood of amplesize will be placed under the bearing corner.


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6.9.10 Cork Tile section and clean the exposed underfloor of adhe-

Cork tile may be laid on wood or concrete floorsthat are not in direct contact with the ground. Tilesare made of raw cork and resins, are unbacked, andare c inch thick. They have good durability butonly fair resistance to grease and alkalies. Tilesshould be laid according to the manufacturer'srecommendations.

6.9.11 Rubber Tile and Sheet

Rubber-tile flooring may be laid on concrete floorsin direct contact with the ground if the floor is notbelow grade. Slabs on grade must be membrane-waterproofed to receive rubber tile and sheet.Rubber tiles are equal in durability and maintenancerequirements to linoleum and vinyl tiles. For slip-resistant floors, rubber-sheet floor coverings aremade with a wearing surface of a compound ofnatural, synthetic, or reclaimed rubber, with orwithout a backing of cotton or fabric. Rubbersheeting conforms to Federal Specification ZZ-M-71d. Finished surfaces have longitudinal, diamond-,pyramid-, or knob-shaped corrugations.Thicknesses range from c to ¼ inch and widthsfrom 24 to 42 inches. Rubber tiles and sheets arelaid according to the manufacturer's recommenda-tions.

6.9.12 Repair of Resilient Floor Coverings

6.9.12.1 Repairing Linoleum. Repair comparative-ly small areas of damaged linoleum by laying outthe area along rectangular lines and laying anoversized section of new linoleum over the dam-aged area. Cut through the two layers simulta-neously to insure a tight fit. Remove the damaged

sive, dust, and dirt. Replace damaged felt lining.Apply a linoleum adhesive to the exposed surfaceand fit the new linoleum in place. Roll the area witha linoleum roller and place weights of suitable sizeon the patch to assure proper adhesion.

6.9.12.2 Repairing Resilient Tile. Repair resilienttile by removing the damaged section and replacingit with new material. Tile is more easily replacedthan linoleum because of its smaller size. Afterremoving damaged tile, scrape the exposed arealevel, and clean off all mastic, dust, and dirt.Replace damaged felt lining. Install new tile insuitable cement or mastic in accordance with themanufacturer's recommendations.

6.9.12.3 Resurfacing Cork Tile. Improve theappearance of cork tile after abuse of long serviceby sanding the tile with No.1-½ sandpaper,followed by finish sanding with No.00 paper. Aftereach sanding, sweep the floor to remove cork dust.After the final sanding, wash the floor with a syn-thetic detergent cleaner, rinse it by damp-moppingwith clean water, and dry it. Apply two or threecoats of water-emulsion wax suitable for cork tile.Buff the wax with a polishing machine after eachcoat has dried.

6.9.13 Maintenance of New Resilient FloorCoverings

Newly installed resilient floor covering should bemaintained in accordance with Tri-ServicesManual "Military Custodial Services Manual" (TM5-609, NAVFAC MO-125, AFM 91-30).

SECTION X—RESINOUS FLOOR FINISHES

6.10.1 General not always a clear distinction between these types.

Resinous floor finishes (also known as seamlesscoating systems) are a relatively new development.As such, only very limited experience has beengained in the selection, installation, maintenance,and repair of these floor systems. The resinousfloor system is composed of the resins, hardener,and fillers. The resin is the binder which holds themass together and bonds the floor coating to thebase floor. The hardener converts the liquid resininto a solid. The filler, which can be any materialfairly inert to chemicals, adds to impact strengthand brings the coefficient of thermal expansion ofthe resin closer to that of the base floor. Despiteconvenient classifications into generic types of resinbinder, chemical analysis by the National Instituteof Science and Technology indicates that there is

No matter what the generic type (epoxy, polyester,polyurethane), the prepolymer and catalyst(hardener) must be chemically designed for theparticular floor coating. The properties andperformance of the combination of materials willvary widely with the particular formulation. Theresin binders may also be combined with otheringredients, such as aggregates, to provide awearing surface.

6.10.2 Materials

Outlined below are the components for the resinousfloor. It must be stressed that these componentsmust be from the same manufacturer andformulated for the particular resinous floor cover-ing. Materials must be stored for at least 24 hoursat a temperature of not less than 50E F (10E C).


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Methyl methacrylate (MMA) based acrylic reactive 6.10.4 Floor Systems Selectionresin systems generally cure down to 24E F (4.5EC) (and lower) and do not require special storagebefore use.6.10.2.1 Primer. Primer, a material recommendedby the manufacturers of the resin, will penetrateinto the pores of the substrate (base floor). Theprimer must blend with the topping to form a per-manent monolithic floor-covering system.6.10.2.2 Resinous Binder. This is the basic resin-ous material which will constitute the majoringredient in the floor-covering system.6.10.2.3 Catalyzers (Hardeners). A catalyzer is aproduct which will catalyze or harden the resinbinder when added in the correct proportions andthoroughly mixed.6.10.2.4 Fillers. This material is composed of inertmineral or cellulosic ingredients best suited for theresin binder. Normally, fillers are used to impart thecolor and physical characteristics to the floorcovering.6.10.3 Types

Resinous floor coverings are classified by generictype of resin binder and subclassified by method ofapplication. Some resinous floor coverings are gen-erally known as decorative, brush-on or roll-on,monolithic flooring. This type of covering is closelyrelated to floor enamel. Another type of covering ismixed with the aggregate in a concrete mixer andis troweled on in the same manner as a concretetopping. A third type also resembles a concretefloor topping, but the aggregate is decorative,usually marble chips, and after hardening it isground with a grinder.6.10.3.1 Epoxy. Epoxy coverings may be brushed-on (rolled-on), troweled-on industrial or thin-setterrazzo.6.10.3.2 Polyester. Polyester coverings may betroweled-on industrial or thin-set terrazzo.6.10.3.3 Polyurethane. Polyurethane coveringsmay be brushed-on (or rolled~n) or troweled-on in-dustrial.6.10.3.4 Methyl Methacrylate. MMA-based reac-tive systems are used from brushed-on (rolled-on)coatings to self-leveling and troweled-ondecorative industrial and commercial type floors.They can generally be trafficked 1 to 2 hours afterapplication.In addition to the types mentioned above, it is ex-pected that advances in technology will developnew seamless floor (and wall) covering systemswhich will consist of layers of different generictypes such as an epoxy base and a polyurethanefinish.

The selection of the particular floor system dependson the ability of the system to withstand exposureconditions. Polyesters are suitable for resistance todetergents but not for exposure to strong alkalinesolutions like sodium hydroxide. Epoxies shouldnot be used where resistance to oxidizing acids orresistance to temperature more than 130E F (54.5EC) are required. MMA-based systems are excellentagainst heat shock, mechanical impact, salts,alkalies, organic and inorganic acids but should notbe used where solvents are spilled regularly. Wheredoubt exists as to the suitability of a particularresinous material, inquiries should be directed tothe next highest echelon of command.

6.10.5 Preparation of Substrate

This is the most critical phase of the installation ofresinous floor-covering systems. Most bond failureshave been traced to improper preparation of thesubstrate surfaces. In the case of newly pouredconcrete surfaces, the concrete must be a minimumof 28 days old. A distinction should be madebetween new concrete and existing slabs that needrehabilitation work. New slabs are prepared bysandblasting and abrasive, steel shot blasting. Oldslabs should be prepared mechanically by sand-blasting or abrasive blasting, scarifying orscabbling. The substrate surface must be sweptclean and must be free of paint, oil, grease, or anyother material that will affect the bonding or thesmoothness of the applied floor covering. In thecase of a concrete slab, the surface should beetched with a 10-percent solution of muriatic acidapplied by mopping or brooming. Allow the acid toremain about 10 minutes or until the bubblingceases. Thoroughly wash the surface with cleanwater, removing all residue. Allow the surface tothoroughly dry. Cracks or uneven areas of the sub-strate must be patched or repaired with materialsrecommended by the resin manufacturers.

6.10.5.1 Priming When the surface is thoroughlydry, the primer is applied insuring that the entiresurface is coated without flowing and collecting indepressions.

6.10.5.2 Application. The interval between prim-ing and application of the resinous floor covering isin strict accordance with the manufacturer's in-structions. The coating is applied to the finishedthickness depending on the type of resin, the expo-sure of the floor covering, and the decoration de-sired. Thicknesses range from / to / inch. Cove3 5

16 16

bases are normally cast-in-place, resinous, covering


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material with a 1-inch radius curve and are from 4to 6 inches high.

6.10.5.3 Finishing. Brush-on (or roll-on) types arefinished with a sealer if required by the manufac-turers. Troweled-on types are troweled to auniform smooth finish. After curing, in accordancewith the manufacturer's directions, a sealer coat isapplied. Thin-set terrazzo must have the exposedsurface ground smooth after the curing iscompleted. Grout is applied and worked intopinholes and other voids. Excess grout must beremoved as soon as possible. After the grout hascured, the surface should be ground to a smoothuniform finish. After the final grinding, the surfacemust be washed with a neutral cleaner and rinsedwith water. When the surface is thoroughly dry, thesealer coat is applied.

6.10.5.4 Protections. All completed work shouldbe protected until the floor is placed in service.This is especially true when other constructionoperations are in progress.


Resinous floors are maintained the same as terrazzofloors. Normal custodial services provide thenecessary maintenance. Due to the recent use ofthese floor covering materials, few floors have beenrepaired. When repairs have been made, MMA-and polyester-based systems have proved to be themost successful because the new resins bondmonolithically to the existing systems withoutleaving cold joints. The damaged area and 6 inchesadjacent to the damaged area are completelyremoved down to the substrate (base floor). Thesubstrate is prepared as for a new floor (see para-graph 6.10.5). The resinous material is leveled withthe existing floor covering. Aggregate or decora-tive chips are added if required. When curing iscompleted, some systems may require grinding theedges smooth. Present practice indicates that thepreparation of the substrate is the key to successfulresinous floor repairs.

SECTION XI—STAIRS

6.11.1 Repairs graph 6.3.2.

6.11.1.1 Wood Stairs. Exterior wood stairs aresubject to weathering and mechanical abuse. Nor-mally, damaged components should be removedand replaced in kind. Maintenance on interior woodstairs usually involves treads. Squeaks indicateloose treads, which can be corrected by drivingfinishing nails through the treads into the riser orcarriages, or by removing the molding under thetread overhang, driving wood wedges between thetread and riser, renailing the tread tightly, andreplacing the molding. In open string stairs, a treadthat is worn but not split or broken may beremoved and reversed. Split, broken, or otherwiseseriously damaged treads should be replaced withnew boards. Housed treads that cannot be removedmay be repaired by leveling the worn surface withasphaltic mastic or other suitable plastic materialsand covering the tread with a suitable floorcovering. Plain and nonslip nosing of steel, brass,bronze, aluminum, and molded hard rubber arecommercially available and should be appliedaccording to the manufacturer's recommendations.

6.11.1.2 Concrete Stairs. Concrete stair treads The fabric has a backing of pressure-sensitivethat are cracked, chipped, or spalled may be adhesive. Rubber mattings may also be applied topatched according to recommendations in para- treads to reduce slipping hazards.

6.11.1.3 Terrazzo Stairs. Terrazzo stairs, becauseof the nature of the material and general conditionsof use, usually require limited maintenance.Cleaning for removal of discoloration may be nec-essary and should follow the procedure recom-mended in paragraph 6.4.3.

6.11.1.4 Metal Stair& Metal Stairs, especiallywhen exposed to the weather or corrosive agents,should be given a coat of rust-resistant paint.Rusted fasteners should be replaced and properlysecured.

6.11.2 Application of Coverings

The elimination of hazards may require the appli-cation of slip-resistant coverings on treads of exte-rior or interior stairways. Some types of bitumi-nous-base coverings are furnished with a slip-re-sistant wearing surface, which makes them efficientmaterials for use on stair treads. A mineral-surfaced, nonslip covering, consisting of siliconcarbon grains coated on a heavy, toughsemisaturated fabric, is also available commercially.


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SECTION XII—CARPET

6.12.1 General 6.12.2 Replacement

Carpeting is a common authorized floor covering If carpeting is to be removed and replaced, thefor uses in quarters and select administrative, rec- floor should be inspected and prepared by remov-reational, and education facilities. Guidelines on the ing and replacing deteriorated or looseselection and characteristics of authorized carpeting underlayment or subflooring. Large cracks inmay be found in Engineer Technical Letter 1110-3- concrete floors should be repaired as outlined in323, "Carpet in Army Facilities," NAVFAC Design paragraph 6.3.9.6.Manual 14.2, "Carpet Selection Guide," and AirForce Design Manual.

6.12.1.1 Care and Maintenance. Routine custodial been completed. Room humidity and temperaturecare and maintenance of carpets should be main- must be within limits recommended by thetained to avoid excessive wear caused by surface manufacturer and no less than 60E F (15.6E C), forsoil penetrating to the lower pile and backing. Pro- 24 hours before and after installation. Planning forcedures for care and maintenance are in the Tri- the replacement should minimize the number ofService Manual (TM 5-609, NAVFAC MO-125, seams with no seams occurring perpendicular atAFM 91-2 Military Custodial Services. doorways.

6.12.1.2 Repairs 6.12.2.2 Installing Carpet Guards. Carpet guards

a. Spot Repairs. Small repairs to carpet pilemay be made by resetting individual tufts in theaffected area. This procedure may be used in casesof small burns or serious stains where the carpetbacking is unaffected. Carpet pile should be cutdown to the backing and stubs removed. New indi-vidual tufts should be stripped from a piece of 6.12.2.3 Installing Tackless Carpet Stripping.scrap carpet or from an inconspicuous part of the Standard tackless carpet stripping should be in-existing carpet by unraveling the edge of the scrap. stalled around the perimeter of the room at a dis-Prepare the area to be repaired with a thin coat of tance of not more than ¼ inch from the wall base.latex adhesive and install individual tufts, doubled,into the carpet backing using a tuft-setting tool.The tufts should be installed from the edge orcorner of the repair and as close together aspossible. Trimming or gentle pulling of the tuftswill provide a smooth surface.

b. Plug Method. Larger repairs or repairs it is secured. The cushion may be secured usinginvolving damage to the backing may require the tacks spaced 6 inches apart around all edges, tapedremoval of a portion of the carpet and replacement with 4-inch-wide tape as recommended by thewith a matching plug. A piece of matching carpet manufacturer, or spot cementing to the subfloor.should be placed over the affected area and aligned All seams should butt tightly and run in theto insure that the pattern and direction matches opposite direction of any carpet seams. NOTE: Inexactly. The carpet may be temporarily tacked in large rooms or when excess shifting of carpet isplace while cutting. Using a sheet-metal disk plug anticipated during installation, the carpet may beor metal straightedge, cut both layers of carpet laid out in the room prior to installing the cushionbeing careful not to fray the edges or damage tufts. and turned back to allow installation of the cushion.Avoid cutting into the carpet padding. Replace the Once the cushion is secured in place it should bedamaged area with the new plug to insure a proper trimmed to butt with the tackless strips and edgefit. Seams should be taped with 4-inch-wide carpet guards.seaming tape as recommended by the carpetmanufacturer. The tape should be bonded withcarpet seam adhesive. Insert the patch insuring aproper fit and allow the area to dry, undisturbed,for a minimum of 6 hours.

6.12.2.1 General Installation. Install carpetingafter other finishing operations, e.g., painting, have

should be installed wherever the edge of carpet isexposed to traffic. This should be precut to theexact dimensions of all openings except where an-other device, such as expansion joint cover systemsor thresholds, are located with an integral carpetbinding bar.

6.12.2.4 Installing Carpet Cushion. Carpet cush-ion is usually laid with the slip-resistant face down;however, check with the cushion manufacturer forthe recommended method. The cushion should becut approximately 6 inches longer than required tobutt to the tackless strip and trimmed in place after

6.12.2.5 Installing Carpet. Carpet is cut not lessthan 3 inches larger than the net room size. Instal-lation begins in one corner of the room away fromopenings. Stretching the carpet onto the tacklessstrip is done with a knee kicker or power stretcherwhich have been adjusted to insure that the teeth


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do not become exposed through the backing of the 6.12.2.7 Width Stretch. The width stretch is per-carpet. To start the installation, the carpet should formed in the center of the wall opposite the twooverlap the walls approximately 1½ inches in the corners previously installed. The carpet is securedstarting corner. The carpet should be kicked onto to the strips in the same manner as the lengththe tackles strips and trimmed 6 inches in each stretch. Instead of using a kicker, the powerdirection from the corner. The carpet should be stretcher is used to secure the entire half of the wallkicked onto the tackles strips for up to 3 feet from beginning at the point of stretch halfway towardthe corner angling the kicker slightly away from the one corner and then the other. The base of thecorner. power stretcher should not move during the width

6.12.2.6 Length Stretch. With the beginning cornerset, the carpet should be stretched in length by 6.12.2.8 Completing the Stretch. The installationinstalling the second corner. This should be the should continue along the wall opposite the begin-corner farthest from the beginning along an ning wall using the power stretcher with no angleadjacent wall, not opposite. The length stretch to the tubes. This is followed by both end walls,should use a power stretcher with a head placed also using the power stretcher in a straight stretch.three inches from wall. The carpet is held on thetackles strip with a spreader which is releasedslowly to allow the carpet to hook onto the strip. Akicker is then used to install the corner in the sameway as the beginning corner and the entire startingwall between the two corners.

stretch installation.

6.12.2.9 Cutting. Excess carpeting along wallsshould be trimmed with a trimmer or sharp utilityknife with approximately ¼-inch excess. The excessis then pressed into the gully between the tacklesstrip and the wall.


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CHAPTER 7

DOORS, WINDOWS, AND BUILDERS’ HARDWARE

SECTION I—MAINTENANCE AND REPAIR OF DOORS

7.1.1 General This forces the door closer to the jamb at the lock

Exterior doors are more subject to abuse andweathering than interior doors, but, in general,defects and corrective measures are similar.

7.1.2 Periodic Inspection

Doors should be inspected quarterly for poor fit-ting, including loose or broken battens; deterioratedor damaged frames; paint deterioration; materialdamage; cracked or broken glass; split or crackedwood panels; warped or dented metal; warped orbroken screening; broken or inoperative hardware(locks, hinges, and sliders).

7.1.3 Wood Doors

7.1.4 Butt-Hinged Doors

Mechanical injury to mullions, headers, jambs, orhardware usually causes trouble with large wood-batten framed and braced doors. Decay, resultingfrom exposure to weather or shrinkage of doormembers, also causes distortion or failure. Fre-quently, the free edge of the door sags and causesthe door to bind at the bottom and open at the top.

7.1.4.1 Checklist for Repair

Effective remedies may be determined by firstchecking the following:

a. Examine the jamb opening to see that thehinge and lock sides are plumb and parallel.

b. Check the doorhead to see that it is level.

c. Check anchorage of the jamb.

d. Check anchorage of hinges.

e. Check lock faceplates for projection beyondthe face of the door.

f. Check all members for swelling, shrinking,or warping.

7.1.4.2 Repairs. The following procedures applywhen the door itself has shrunk or is warped, swol-len, or sagged.

a. When a door shrinks, remove the hingeleaves and install a filler (cardboard or metal shim)at the outer edge of the jamb and hinge mortice.

edge. If the hinge pins do not bind, the door willoperate satisfactorily. Each hinge should beshimmed equally to prevent the door frombecoming hinge bound. When the door has swelled,place shims in the inner edge of the hinge morticeas shown in figure 7-1.

b. Restore a warped door to its normal shapeby removing it and laying it flat. Weighting it downmay also be necessary. If it is still warped after areasonable length of time, battens screwed to thedoor help restore it to true plane. Screw eyes, rods,and turnbuckles help straighten a door by graduallypulling it into place.

c. Install a diagonal batten brace from the topof the lock side to the bottom of the hinge side torepair a sagging door permanently. The diagonalbrace must cover the joint between rail and stileand be securely fastened to both members, at topand bottom, and other intermediate rail members.Temporary repair is made by installation of a wirestay brace equipped with turnbuckles and placeddiagonally in the reverse direction from a battenbrace.

d. Doors or door members may require rebuild-ing because of neglect or abuse. Remove the doorto a flat surface and replace the damaged member.Carpenter's clamps assist in holding door memberssquare while nails or screws are driven.

e. Trim the door when the preceding methodsfail to correct the trouble. However, do not cutdoors immediately following rain or damp weather.When dry, the door may fit too loosely.

7.1.5 Wood Panel Doors

Failures in panel doors are similar to those in largewood doors. In addition, doors are subject tobinding at the hinge edge, friction between the deadbolt and strike plate, or between the latch-bolt andstrike plate.

7.1.5.1 Locking. Trouble with the locking appara-tus is generally caused by defective knobs or locks.Check the knob to determine whether the spindle isworn or only loose. Where a lock does not move


7-2

smoothly, replacement may be necessary, although the door securely. Vertical settlement andrepair of worn parts or lubricating with graphite horizontal deflection will cause the jamb openmg tofrequently overcomes the difficulty. become out of square. On most wood doors, the

7.1.5.2 Rattling. An excess of space between thedoor and stop head causes the door to rattle. Re-moval and refitting of the head stop while the dooris closed remedies this difficulty. The door may alsorattle because of too much play between thelatchbolt and strike plate. Correct this condition bymoving the plate back toward the stop.

7.1.5.3. Loose Hinges. Hinges become loosened if hinges from the door and screw a wood strip to thea door is too tight on the hinge edge and binds door, extending the entire length. Countersink allagainst the hinge jamb. If the door has plenty of nails or screws, and place putty over all holes.clearance on the lock side and the entire pin seemsto move slightly when the door is closed, loosenboth hinges at the frame and insert card-boardunder the jamb leaves along the outer edges. Tomake a uniform space between the jamb and thedoor, insert a strip of cardboard under the inneredge of the top hinges in the leaf which is fastenedto the jamb. This usually corrects the trouble bypulling the upper part of the door closer to the 7.1.5.7 Uneven Side Margins. It is seldom neces-jamb. However, considerable space above the door sary to plane a door if trouble is caused by loose orand along the outside (lock edge) may result. In improperly morticed hinges. However, if planing isthat case, loosen the screws in the leaf of the necessary because side margins are uneven and thebottom hinge, which is attached to the jamb, and door strikes at top or bottom because of settlementinsert cardboard under the other edge. If the hinge of the frame or similar causes, locate the points ofhas been pulled loose and the wood screws have friction. It is easier and less noticeable to plane thedamaged the wood fibers on either the door or hinge edge. Bevel the lock edge of the door aboutjamb, the holes may be plugged with wood plugs or c inch to facilitate closing. If the door still strikesfilled with plastic wood. along the lock edge, plane the hinge edge and cut

7.1.5.4. Warping. A warped door that has springinward or outward at the hinge edge is impossibleto close without considerable pressure against the 7.1.5.8 Sticking Damp weather often causes abulging part. This trouble is generally overcome by door to stick. Absorption of moisture results inplacing an additional hinge midway between the swelling of the framework and door. If the door hasother two to hold the door straight. If another an even margin along the top and bottom edges andhinge cannot be obtained, temporary repair is made if the hinges are firm, the hinge edge must beby shifting the hinges outward or inward on the planed. It is best to plane the hinge edge becausejamb, as shown in figure 7-1. Adjust stops ac- hinges are more easily removed and remorticedcording to the position of door when closed and than the lock. Take care not to plane off too muchlatched. wood. When it is necessary to trim a door for

7.1.5.5 Settling and Shrinkage. Settling of thefoundation or shrinkage and deflection of framingmembers often causes trouble at door openings.When the greatest settlement is on the hinge side ofa door, the door will tend to become floor-bound atthe lock side. When settlement is greatest on thelock side, the door will bind at the head jamb. As aresult, the bolt in the lock will not be in alignmentwith the strike plate, making it impossible to lock

simple correction is to plane as required at eitherthe top or bottom rail for proper clearance.Another method, more complicated but producingbetter results, is to lift off the strike plate and nailor screw a wood strip extending up and down theentire length of the door frame, as shown in figure7-2. It is necessary to cut a hole in this strip for thelatchbolt. An alternate method is to remove the

7.1.5.6. Latching. When the latch does not operatebecause of poor alignment with the strike plate(figure 7-3), enlarge the hole in the strike plate byfiling. If the bolt strikes squarely on the plate andrequires removal of as much as c inch of metal,remove the strike plate and raise or lower it asnecessary.

in the hinge leaves flush with the surface, ifnecessary.

better fitting, carefully mark the amount to beplaned, allowing clearance on all sides of ap-proximately the thickness of a dime. To determinethe correct amount of wood to be removed, set thedoor hard against the hinge side, wedge it plumb,and scribe the desired thickness of material to beplaned off. When planing or cutting is completed,repaint the edges before rehanging the door.


7-3


7-4

7.1.5.9 Bevel. Proper bevel for wood doors of 2 fits its opening with proper clearances.feet 8 inches to 3 feet in width is about / inch per Weatherproofing and caulking must be maintained1

161 inch of door thickness. On doors of smaller width in a workmanlike manner. Mechanically operatedthat are of equal thickness, the bevel should be doors must be removed and straightened, repaired,increased proportionately to the decreased width of or replaced. Repair material and finishing shoulddoor. On wider doors, the bevel can be decreased match the existing material. Shop repair of metalproportionately to the increase in width of the doors should meet acceptable standards fordoor. See figure 7-4. welding, riveting, and sightliness. Replacement of

7.1.6 Metal Doors

7.1.6.1 Types. Metal doors, commonly used inwarehouses, hangars, stockrooms, mess halls (gal-leys) and other areas where hard service or indus-trial operations require them, are of various types:metal, clad, hollow metal, and solid metal, withvariations including interchangeable glass andscreen panels.

7.1.6.2 General Maintenance. Because most metaldoors and fittings are shop designed and fabricated,it can be assumed that they will maintain theirshape and mechanical operating abilities providedhinges, locks, and other fittings remain secure intheir fastenings. This is accomplished by checkingscreens, nuts and bolts, and special fasteners andoperating devices regularly and keeping them tight 7.1.7.1 Types of Doors. The most common typesand in good order. Building settlement, mechancial of doors, as described in NFPA Standard 80, "Firefailure, and collision may require investigation and Doors and Windows," are composite doors ofcorrective measures for a basic cause of wood, steel or plasic bonded to a solid core; hollowmisalignment in the structure framing itself. Frames metal doors; metal-clad doors of metal over woodmust be plumb and corners square so that the door cores; sheet metal doors; rolling steel doors;

surface metal on fireproof, metal-clad wood doorsmust be weathertight and of material of the samegage as originally provided. Service doors in messhalls (galleys), stockrooms, and other areas wherepersonnel pass in and out frequently with armsloaded should be provided with kick plates andwith bumper protection to prevent slammingagainst walls.

7.1.7 Fire Doors

Fire doors are specifically designed and installed torestrict the spread of fire and smoke in facilities.They are usually of metal, metal clad, or woodconstruction with or without lights as describedbelow and are classified in accordance with NFPAStandard 252 or other approving authorities.


7-5

curtain-type doors; and wood core doors of wood fire protection spread ratings may include wiredor plastic bonded to wood core. Doors with lesser glass lights.

7.1.7.2 Inspections. Doors must be kept operable large doors should be maintained according to theat all times and should be kept closed. Mainte- manufacturer's recommendations.nance includes frequent inspection of hinges,catches, closers, latches and stay rolls. Lights, ifany, and door face coverings, chains or cables,should also be inspected. In addition, metal- andtin-clad doors should be inspected for dry rot.Areas surrounding doors should be inspected forblockage and doors inspected for tampering such aswedges to keep the door open or devices whichinhibit their opening.

7.1.7.3 Maintenance. NFPA Standard 80 and themanufacturer's recommended maintenance shouldbe followed. Lubricate guides and bearings andadjust chains and cables on counterbalanced doorsas needed to insure proper operation. Replace wornhardware immediately. Broken light panels shouldbe replaced with at least ¼-inch-thick wire glass.Faults in face coverings should be immediatelyrepaired as described in paragraph 7.1.5.2.

7.1.8 Hangar and Warehouse Doors

Doors used in hangars and warehouses are com-monly of the rolling type and motorized; theyimpose extreme loads on the narrow bearing sur-face of supporting rails. They require specializedmaintenance in accordance with the manufacturer'srecommendations. If major warping or dis-placement of sliding panels occurs, engineeringpersonnel should be consulted on repair. Settling orfailure of roof trussing can cause displacement ofoverhead rails and guides, imposing stresses on thepanels. Maintenance of large metal areas of doorsis similar to that for metal sidings, as recommendedin chapter 4. Complicated devices for operating

7.1.8.1 Minor and Routine Maintenance.a. Keep rails, guides, springs, and rollers secure

and free from dust, dirt, corrosion, and obstruction.b. Keep upper rails and rollers lubricated ac-

cording to the manufacturer's recommendations.c. Check and maintain alignment of rollers and

rails.d. Check guides for security and alignment.

Straighten bent guides.e. Repair damaged glazed sections promptly.f. Inspect and lubricate motors as

recommended by manufacturer.g. Keep hinges and springs free from dirt,

debris, and corrosion, and lubricate them regularly.Replace sprung or broken hinges and springs andother door fittings.

h. Keep locks and latches lubricated and ingood repair.

7.1.8.2 Adjustment to Hangar Door Guides. Themethods used in adjusting door guides depend onthe type of door mechanisms involved. The detailedprocedures explained herein are for a particulartype of construction. However, the principlesapplied in the adjustment of this door can be usedon many types of door and truss configurations.The causes of binding of sliding hangar doors intimber truss-type hangars are discussed inparagraph 3.4.9.3.

a. Considerable difficulty has been encounteredin hangars containing Pratt trusses with a span of


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120 feet. Usually the trusses over the doors carry 7.1.9 Cold-Storage Doorsconsiderable additional loads, for the door canopyand guides are cantilevered out beyond thosetrusses. The 120-foot trusses are usually erectedwith a 4- to 6-inch camber, and the door guides areadjusted for a fixed distance from the deck. Thedistance between truss chords and door guides will,therefore, vary, the greatest differences being at thecenter of the span.

be inspected for damage or deterioration, andb. A practical means for adjusting the doorguides is to raise the outriggers at their point ofcontact with the bottom chord of the door trusses.This is accomplished by driving oak wedges be-tween the outriggers and chords. Before raising theoutrigger, it will be necessary to notch the sillssupporting the bulkhead; otherwise, the entirebulkhead will be raised with the outrigger. It maybe necessary to raise the canopy to relieve thestrain when driving the wedges. One jacking tower,made up of 6 x 64nch timbers, and suitable crossbracing, should be constructed for this purpose. Bysetting the tower under each outrigger, in turn, andjacking it to its predetermined height, the wedgescan be installed and the jack removed. All boltsconnecting the outrigger to both trusses should beloosened while performing this operation.

c. In some hangars, the arrangement of outrig-gers and door guides is somewhat different. Theseguides are bolted to the underside of the outriggers,with a spacer timber between the flange of the "T"guide and the underside of the outrigger. Theguides can be adjusted in this case by removing thespace timber, and, in its place, installing a correctnumber of shims or blocks to bring the guides tothe proper grades. Where corrections are made inthis manner, it will be possible to readjust theguides at a later date, if necessary, by removingsome of the shims. The only equipment required forthis work, other than the usual mechanic's tools,will be a portable scaffold of sufficient height toreach the canopy.

d. When making adjustments to the doors, thewheel adjustment should be taken up as much aspossible and the wheels well greased. Check therails and chip away any concrete rubbing againstthe flange of the wheels. The door rails should bekept clean at all times. It is recommended that theoperation forces be instructed to sweep out thetracks daily. Exercise extreme caution when ad-justing door guides, for the guides have only a fewinches bearing on the door at the top; and, if theguides are raised too much, the doors will tumbleover, probably with disastrous results. Adjustmentsto door guides should not be made by cuttingmaterial from the stem of the "T" rails, as this onlyreduces the bearing surface of the guides.

Doors in cold-storage rooms, including meat trackdoors, should be checked for tight closing. Latchesshould be adjusted if necessary. Hinges and latchmechanisms should be lubricated regularly. Gasketsshould be cleaned and checked for necessaryreplacement. Special attention should be given tolow-temperature installations, where nonfreezetype(electrical resistant) gaskets are used. Doors should

bumper guards checked. Ceilings and walls shouldalso be inspected for loose insulation, cracks, orother defects in wood, cement, or mastic finishes.Wall and corner guards should be checked forcondition. Meat tracks should be secure. To reducedeterioration, tracks should be cleaned andrepainted as necessary.

7.1.10 Detention Doors

Detention doors should be inspected regularly forsecurity of locking devices. Breakout alarms at-tached to door locks should be checked for oper-ational readiness. Electrical or pneumatic controlsfor simultaneous locking and unlocking of doors inlarge, cell-block installations should be checked byqualified personnel. Locking devices and hingesshould be lubricated regularly.

7.1.11 Storm Doors

Storm doors are commonly made of wood oraluminum, with appropriate glazing. Wood stormdoors should be maintained and repaired accordingto the manufacturer's recommendations.

7.1.12 Screen Doors

Screen doors, usually made with wood or alumi-num frames, should be fitted with wire guards andwood or metal push bars on the inside to avoidpressure on the screening in opening them. Doorsshould be sized or trimmed to allow proper clear-ance at the head, jambs, and bottom. Too muchclearance will defeat the purpose of excluding in-sects, but doors should not stick or bind, whichcauses damage to the frames under traffic. A sag-ging screen door can be straightened by the use ofa metal rod with a tumbuckle. One end of the rodis fastened to the face of the frame, at the center ofthe intersection of the bottom rail and the outervertical rail. The other end is fastened as high onthe face of the hinge rail as it will reach. Thetumbuckle is then turned to shorten the rod andthus lift the bottom rail. Doorframes are maintainedas recommended in paragraph 7.1.3. Screenmaintenance should conform to recommendationsin paragraph 7.2.8.


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SECTION II—MAINTENANCE AND REPAIR OF WINDOWS

7.2.1. Periodic Inspection counterbalanced by sash weights, spiral spring

Windows should be inspected for loose-fitting ordamaged frames, ilifitting or broken sashes,cracked or broken glass, deteriorated putty, brokenor worn sash cords, and missing or brokenhardware. If atmospheric conditions cause ordinaryputty to crumble quickly, plastic glazing compoundshould be substituted. Leaks may be caused bymaterial shrinkage. Frames and cover molds ofwood windows should be inspected, along withsills, jambs, and heads of metal windows. Openjoints should be caulked. A slight shrinkage ofputty away from the glass can often be corrected byneedle glazing with a soft plastic compound. Rustspots on metal sashes and frames should be wire-brushed or sandpapered, cleaned with a ragsaturated with mineral spirits, and then spot-painted.7.2.1.1 Types of Windows. The following discus-sion is extracted from Building Construction, Ma-terials and Types of Construction by WhitneyClark Huntington and Robert E. Mickadet, courte-sy of John Wiley and Sons, New York. The usualtypes of windows, regardless of materials in theirconstruction, are illustrated in figure 7-5. The glassareas in these examples are subdivided in variousways which may have no significance to the type ofwindow illustrated. Some windows may includeonly a single pane of glass. Subdivisions may bemade to permit the inclusion of ventilating units,for convenience in cleaning, to limit glass size forsafety, for architectural effect, or for other reasons.Various types of windows or sashes are oftencombined as a single window opening.7.2.1.2 A fixed window (figure 7-5(A)) makes noprovision for natural ventilation.7.2.1.3 For double-hung window (figure 7-5(B)),both sashes slide vertically, with the weight of each

balances, or tape spring balances similar to clocksprings. The sash is easily operated dnd edgefriction will hold it in any set position. For a single-hung window, only the lower sash operates. Sometypes are arranged so that the sash can be removedfrom the inside.

7.2.1.4 One or both sashes for a horizontal-slidingwindow (figure 7-5(C)) may be arranged to slide.Some types are also arranged so that the sash maybe removed from the inside. Heavy sashes are oftenprovided with nylon rollers for ease in operation.Sashes are sometimes suspended from rollersoperating on overhead tracks.

7.2.1.5 In general, any hinged window is a case-ment window. It may swing out or in and may behinged at either side, the top, or the bottom but theterm is usually applied only to side-hingedwindows. An outswinging casement window withtwo sashes is shown in figure 7-5(D). Each sashswings on extension hinges attached to the hangingstile of the sash and the jamb of the frame. Theextension provides an open space between thehanging stile and the jamb to facilitate cleaning theoutside. For an inswinging casement window(figure 7-5(E)), extension hinges are used to makethe sash swing clear of the inside surface of thewall. One or more casements of either type may beincluded in a single opening. For example, threesashes could be included by providing a mullionbetween a single sash and a pair of sashes. Out-swinging casements are more widely used than in-swinging. The folding window (figure 7-5(F)) is aform of outswinging casement window with thetwo sashes hinged together on their meeting stilesrather than each to its outside stile. Projection armsare arranged so that the sash operate symmetrically.


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7-9

7.2.1.6 A horizontal-pivoted sash (figure 7-5(G)) of parts in contact prevents much unnecessaryis pivoted at the center. Such sashes are often ar- labor. Binding of horizontal sliding sashes is alsoranged in a row to form a continuous or ribbon relieved by this procedure. When the insidE stopwindow located in a sawtooth roof or monitor and beads of a double-hung window press toc tightlyare operated in unison from the floor by a me- against the sash, reduce the thickness of beads bychanical operator. planing, sanding, or scraping along thE edge7.2.1.7 A vertical-pivoted sash (figure 7-5(G)) isoften arranged to swing in a full circle.7.2.1.8 Sashes may be top-hinged and outswing-ing, top-hinged and inswinging, or bottom-hingedand inswinging (figure 7-4 (I), (J), and (K)).7.2.1.9 Projected windows have ventilation sasheswhich operate like the outward-projecting windowshown in figure 7-5(L). The ends of the arms arepivoted to the stile of the sash and to the frame.Shoes are attached to the top rail of the sash andmove vertically along the stiles, guided by tracksattached to the vertical members at the sides of theopening. An inward-projecting window is shown infigure 7-5(M). If the latter is located at or near thebottom of a window, it is called a hopper ventilator(figure 7-5(N)). If several outward-projectingventilators are located vertically adjacent to eachother and are arranged to be operatedsimultaneously by a single operator, the window iscalled an awning window (figure 7-5(0)). Fixedmeeting rails sometimes are provided betweenadjacent sashes. The downward movement of thetop rail of the projected sash provides an openingthrough which the outside of the outward-projecting sash can be cleaned.7.2.1.10 A jalousie window (figure 7-5(P)) is simi-lar to an awning window except the ventilatingunits are heavy glass slats from 3 to 8 inches widewith metal end supports to which the operator isattached. Adjacent edges of the slats overlap ½inch or more to exclude rain and reduce air infil-tration. There is considerable air leakage whenclosed, and they are usually used only for enclosedporches or where air leakage is not objectionable.

7.2.2 Wood Windows

7.2.2.1 Causes of Failure. Window failures mayresult from various causes, the most common beingweathering. Weathering causes loss of putty andpaint with subsequent deterioration and rotting ofwood members; binding of parting or stop heads;windows forced out of shape by settling, shrinking,or twisting of the building frame; swollen orimproperly fitted sashes; broken or uneven sashcords; and sashes stuck from paint in the pulleystile.7.2.2.2 Binding. When it is determined that thesash in a double-hung window binds because ofpressure against the parting bead, thorough waxing

adjacent to the sash, or move the beads fartherfrom the sash. Carefully plane the top or bottomrail to relieve binding in horizontal-sliding sashes.After planing, coat the sash with linseed oil andwash it when the oil has dried.

7.2.2.3 Settlement. Careful nailing frequently re-stores the shape of frames that are forced out ofshape by settling, shrinking, or twisting of thebuilding. Cutting the sash is not recommended as aremedy.

7.2.2.4 Swelling. Do not cut any window that willresume its original size when properly dry. Cut orplane a sash or frame that is swollen by moistureonly when it is determined that the member is toolarge, even when dry. Remove and plane a sashwhen the vertical edge binds against the pulley stileor running face of the window frame. To locatehigh spots on the sash, rub the sash stile with chalkand then slide the sash from closed to open positiontwo or three times. High spots on the sash areindicated at points where the chalk has rubbed off.

7.2.2.5 Bowing. Occasionally a parting bead be-comes too long, causing a bow in the middle. Inthis case, remove the bead from the frame and cutc to ¼ inch from one end.

7.2.2.6 Broken Cords. Broken or missing cordscall for careful removal of the stop bead. Removethe lower sash from the frame. Knot the cords toprevent them from running through the pulley afterthe window is detached. Remove the parting beadto remove the upper sash. Install new cord, thenreplace the upper sash, parting bead, lower sash,and stop bead, in that order. An economical andefficient substitute for a broken cord or pulley isthe sash control spring. This spring can also beused in lieu of barrel bolts and other devices for thecontrol of a nonbalanced sash. Proper sashoperation requires that the combined clearance ofthe two edges be c to / inch. When installing a3

16control spring on a new sash or old sash removedfrom the frame, nail a spring to each edge of thesash so that the top of the spring is 6 inches belowthe top rail of the upper sash, or 6 inches below thecheck rail or lower sash. Use two 16-gage, ¼-inch-long brads for each spring. When installing thespring on an inplace sash, raise the lower sash atthe high point and hold the spring with prongstoward the frame. Push the spring up between sashand frame, using enough pressure to flatten the top


7-10

spring curve to permit it to slide upward. Install the nails, or other fasteners. Replacement of wornspring on the opposite side of the sash in the same tapes and cords is the major maintenance problemmanner. Lower the upper sash to the low point and with venetian blinds. A check for broken or bentfollow the same installation instructions as above, slats should be made when cords or tapes areexcept push the spring downward. No nails or replaced, since slats can only be replaced byscrews are required. removal of the cords.

7.2.6 Caulking and Sealing7.2.2.7 Balancing Adjustment. When a sash withspiral or pullman-type balances is out of balance,follow the manufacturer's directions for balanceadjustment. Attempts to repair such sashs withoutcompliance with prescribed directions may result infurther damage.7.2.3. Metal Windows

Maintenance and repair of metal windows is usuallyconsiderably less than that for wood. General repairis similar to that for metal doors. Rusting, warping,and sticking of operating devices are the mostcommon failures. It is important to lubricatemechanisms regularly and to keep fastening devicessecure. Problems of alignment caused by buildingsettlement must be adjusted in conjunction withoverall corrective measures, which may involvestabilizing the foundation and framing. Caulkingmust be maintained in good order to preventleakage of moisture and air.

7.2.4 Vinyl Windows

Vinyl windows have frames and lineal componentsof solid PVC or PVCclad wood or aluminum orother combinations of PVC and metals. These win-dows can have low coefficients of heat transmissionand air infiltration which give them an ad-vantageover some other types of windows; however, theycan be more expensive and their selection must bebased on lifecycle cost analysis similar to thatdescribed in appendix C for vinyl siding. Vinylwindows are low maintenance by comparison towood types. The vinyl used is resistant to cracks,peeling, blisters or other surface defects. Painting isunnecessary for vinyl; however, vinyl clad woodmay require painting to the interior surface.

7.2.5 Venetian Blinds

Venetian blinds, when permitted by criteria, shouldconform to Federal Specification AA-V-00200B.Head boxes, usually installed between the revealsof jambs, should be set level on brackets designedto allow convenient removal and replacementwithout damage to the blinds or adjacent surfaces.Brackets should be secured in place with screws,

7.2.6.1 General. Caulking and sealing compoundsare used to seal and waterproof exposed jointsaround wood and metal frames that are built intoexterior concrete and brick, stone, concrete block,glass block, and other masonry. This includes con-trol joints in masonry construction. Caulking com-pounds are used in wood construction for sealingjoints around door and window frames. See figure7-6. Factors which influence joint design andchoice of joint sealant are briefly discussed so thatthese principles may be applied with understandingto the maintenance program.

7.2.6.2 Joint Designs. In movable joints, the ele-ments to consider in the design are their spacing,sizes, and shapes. Since the ability to expand andcontract varies a great deal with different sealants,the percentage of expansion required generallydetermines the sealant to be used. It is thereforenecessary to calculate the anticipated expansionand contraction of the joint due to temperaturechanges. The coefficients of thermal expansion ofthe building material to be sealed, and the spreadbetween the winter low and summer hightemperatures will be used in the design and shapeof movement. The type of sealant can be selected,based on service conditions and movement. Themaximum strain that a particular sealant can endurecan be determined in the laboratory by testing tofailure at different temperatures. Reputablemanufacturers will supply dependable data. Themaximum working elongation in movable joints willbe 10 percent for caulking compounds and a single-component elastomer, and 25 percent for rubber-base sealants. For example, a joint is calculated tomove ¼ inch in width during the period betweenthe high and low inservice temperatures. Using themaximum working elongation of 25 percent forrubber-base sealants, the joints would be 1 inchwide. Then following the rule of thumb that thejoint sealant should be onehalf the width of the jointin depth, the joint would be 1 inch wide by ½ inchdeep.


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7.2.6.3 Sealing Aid and Techniques. A nonmoisture-absorbing backup material

a. Appearance. Well-designed joints have agood exterior appearance, provide economicalmaintenance, and assure weathertight joints.

b. Backup. Backup material is used to control used.depth of sealant in a deep joint cavity. This materialshould be flexible enough to allow the sealant toassume the shape in compression or tension asindicated in figure 7-7.

should be used. Of the resilient materials, the ex-truded closed-cell flexible foams and sponge rubberwill be used for expansion and control joints. Tubesor beads of polychloroprene or butyl may also be

c. Primer. A primer is required on the sealantcontact surfaces of porous construction materials.Depending on weather conditions, primers will dryin approximately 1 hour; coverage will average


7-12

about 200 square feet per gallon, depending on are cleaned, neutralize the muriatic acid with aporosity of the material to be primed. dilute solution of household ammonia, wash the

d. Cleaning Solvents. Solvents will not be al-lowed to air dry without wiping. Perchloroethyleneis used for removing waxes from surfaces to besealed. VMP-naphthlene is used for cleaning inacrylic glazing and for edges of shatterproof glass.Recommended solvents from glass manufacturersalso should be considered. Use a mixture of equalparts of xylene and acetone or toluene or methylethyl ketone for cleaning the glazing surfaces ofaluminum curtain-wall sashes. Ammonium bifluor-ide or muriatic acid may be used to clean masonrysurfaces receiving the sealant. After the surfaces

joint cavity with clean water, and allow to dry.

e. Joint Accessibility. Where practical, a jointshould be designed to be accessible for inspectionand repair. When a joint becomes inaccessible afterconstruction has been completed, the sealantshould be a more permanent type considered thanthat which would be used for the accessible joint.

f. Tip Size. Select the proper tip size for thegun so that the sealant will extrude and fill the jointcavity in one pass.

g. Tooling. Tooling the sealant forces the a similar solvent.sealant into the joint cavity, insures good surfacecontact, and finishes off the exterior surface of thejoint. Tooling white or light-colored sealantsshould be done with a dry or water-wet tool only.Solvents, detergents, or soapy solutions frequentlyused by applicators to allow the tool to slip freely,may discolor sealant surfaces.

h. Masking. Masking either or both surfaceedges of the joint cavity provides a straight line tothe joint, protects wall surfaces from smears, andallows sealant to overlap slightly on the wall,providing a better surface seal. Application issuggested prior to priming, especially on light-colored masonry or other porous surfaces. Mostprimers discolor somewhat with age or weatherexposure. Staining is easily noticeable in areas atground level, entrance ways, steps, etc. Freshsealing compound smears can be removed frommasonry by scraping smears off immediately andrubbing clean with methyl ethyl ketone, acetone, or

7.2.6.4. Surface Preparation.a. Steel Surfaces of Movable Joints. The

surfaces in the joint cavity to be in contact with thesealant will be cleaned of all permanent ortemporary protective coatings before the sealant isapplied.

b. Steel Surfaces to Tight or NonmovableJoints. The sealant may be applied over thepermanent coating. Temporary protective coatingswill be removed to bare metal before applying thesealant.

c. Aluminum Surface of Movable orNonmovable Joints. The aluminum surfaces incontact with selants will be cleaned of thetemporary protective coating. Solvents, when usedfor cleaning, will be as recommended by theapplicators of the coating, and the solvent will bethe nonstaining type. Lintless paper towels shouldbe used for wiping off the solvent cleaner andcoating. The use of rags tends to be too long,


7-13

which results in the surfaces not being well cleaned base and chemical curing are liquid polysulfideor wiped of. Masking tape is also used for polymers and polyurethane polymers. The ambienttemporary protective cover on the area to be in temperature at the time of application will be 40Econtact with the sealant. This tape should be to 80E F (4.5E to 26.7E C), and the inserviceremoved just prior to the application of the sealant. temperature will be-60E to 200E(-51.1E to 93.3E

d. Contact Surfaces of Joint Cavities. Jointcavity contact surfaces that have come in contactwith mold-release agents, curing compounds, sili-con water repellents, floor hardeners, and othersurface treatments will require prior cleaningpreparation before sealants are installed. Wirebrushing, sandblasting, masonry saw cutting, orother similar preparation may be required to cleanthe joint cavity in wood, concrete or masonry con-struction.7.2.6.5. Sealants. The following general require-ments and intended uses will be considered inselecting sealants. When colors are required, theyshould be those standard with the supplier. Forunusual conditions, the purchaser and the suppliershould agree on an acceptable color when cured.Painting over a cured sealant is permissible, but thesupplier should again be consulted. The paintmaterial should have some flexibility when coveringmovable joints.

a. Basic Types. The basic types of jointsealants are the so-called caulking compounds, theone- and two-component rubber-base sealants, theone-part elastomeric sealants (also tapes andbeads), and preformed gaskets. Each type ismanufactured in several different materials. No onematerial or joint design will satisfy all conditions fora good sealant installation. Each type of sealant hasits limitations. Combinations of sealants make someof the most effective seals. Poor joint design, use ofinappropriate sealants, and poor workmanship inpreparing surfaces and applying the sealants willcause failure of the joints and sealants.

b. Bulk-Type Compounds. Broadly classified,sealing and caulking materials are the bulk type,supplied in cartridges, cans, or drums and appliedeither by gun or knife, or the preformed types,supplied in extruded shapes, tapes and beads.

(1) The principal ingredients of oil- andresin-base caulking compound are vegetable,hydrocarbon or drying oil, and resins mixed withasbestos fibers and other inert ingredients. It isready-mixed for immediate use and can be appliedunder ordinary building conditions, 40E to 100E F(4.5E to 37.8E C). It is for use in wood or metalfixed joints and in very limited movable joints. Ithas a short life expectancy unless used where it willbe regularly painted, coated, or have otherprotective coverings.

(2) Two-component types that are rubber

C). They require accurately controlled premixingand careful application and cure to a rubberymaterial with high adhesion. Their intended usesincludes expansion and movable joints in concrete,masonry, and metal; perimeter sealing of metalframes in exterior walls; curtain-wall constructionas joint sealer, and beading and settling of glass andpanels. The self-leveling type is used for joints inhorizontal surfaces, and the nonsag type for jointsin vertical surfaces.

(3) Single-component types that are rubberbase and chemical-curing include sulfides, silicones,and polyurethanes. The ambient temperature at thetime of application will be between 50E and 100E(10E to 37.8E C), except that the silicone type willbe between 0E and 120E F (-17.8E to 8.9E C). Theinservice temperatures will be from -20E to 200EF(-28.9E to 93.3E C), except that the silicone typewill be from-80E to 350E F (-62.2E to 176.6E C).The sealants are premixed and ready for immediateapplication. They require careful handling andstorage and have a relatively long curing time. Theyare intended for use in locations similar to those forthe two-component compounds although thecuring times, application temperatures, and otherfactors will dictate which compound will best servethe joint.

(4) Nonskinning compounds, which arepolybutenes or blends of polybutenes andpolyisobutylenes (butyl) mixed with asbestos fibersor other inert ingredients, are ready-mixed forimmediate use. Ambient temperature at time ofapplication will be from 0E to 10E F. Inservicetemperature range will be from-60E to 200E F. Thematerial is nondrying and the exposed surfaces aretacky. It is to be used in fixed and unmovable jointsbetween metals or glass, as bedding compounds, ininterior joints in protected locations, and in glazingmetal curtain-wall construction. This type ofsealant may be used below grade.7.2.7. Glazing

7.2.7.1 General. Glazing repair consists of sash re-conditioning and replacement of broken glass.Maintenance often involves only replacement ofloose, deteriorated, or missing putty. Glazing itemsin buildings and structures generally should be re-placed using the same type of materials used in -theoriginal work. The quality of replacement materialsshould be improved only when justified by obviousinadequacy of the failed materials, and when


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planned future use of the buildings or structure installed in the sash of control towers and otherwarrants it. Consideration may be given to spaces where occupants are exposed to direct orproviding double-pane insulating window glass reflected rays of the sun. This glass is generally ¼where it can be economically justified. It should be inch thick, clear, ground, and polished. Its solar-noted that glass size is sometimes specified by the heat-reflecting and luminous-transmittance qualitiesso-called "united inches method," which is the sum are described in current Federal Specification DD-of the length and width of the size specified, i.e., G-1403. Where clear vision is not required, theone-half the perimeter. Example: Glass size of 12 rolled figured, blue-green, obscure glass should beinches wide by 15 inches long would be specified as used.27 united inches.7.2.7.2 Flat Glass. Flat glass used for glazing sash,doors, and other uses will conform to requirements usually not less than ¼ inch thick. The surfaceof current Federal Specification DD-G-1403. design may be a series of cylindrically shaped lenses

a. Clear Window Glass. Clear window glass,Type II, Class 1, Quality 96, is recommended forreplacements in hospitals, administration buildings,and other similar structures. The use of Quality 96in quarters and service buildings will afford asavings in material costs. The following schedulemay be used as a guide for thickness and size ofinstalled clear window glass: Single- strength glassshould be used in sheets 400 square inches to 7square feet in area; above that limit, glass / inch3

16thick should be used where plate glass is notrequired.

b. Polished Plate or Float Glass. Polished,clear-vision plate or float glass is used aroundprominent entrances, in large openings, for airdeflectors, shelving, bulletin board doors, andprojection booth observation ports. Polished plateglass should be Type 1, Class 1, Quality 96, andhave a nominal thickness of ¼ inch. stalled to advantage in observation windows in

c. Wire Glass. There are two kinds of wireglass, Type III, Class 1: A (flat) and B(corrugated). Flat wire glass, usually ¼ inch thick,is used in doors, windows, fixed sidewall sashes,and some sky-lights. Corrugated wire glass, /5

16inch or more thick, is used mostly in skylights.Clear, flat wire glass, polished on two sides, is usedin windows and doors of detention, storage, andother buildings where security and clear vision arenecessary.

d. Obscured Glass. Figured glass, Type III,Class 1, Kind A, Form 3, Quality 911, Finish Fl,not less than c inch thick, is used where clearvision is not necessary or is undesirable. Suchlocations would include windows and doors intoilets, baths, dressing rooms, operating rooms,surgical dressing rooms, shops, garages, andwarehouses. Figured or ribbed glass, smooth onone side, is desirable for use in doors and windowsof buildings such as shops, garages, andwarehouses where clear vision is not required.

e. Heat-Absorbing Glass. Heat-absorbingglass, Type 1, Class 2, Style A (or Style B), is

f. Light-Diffusing Glass. Figured glass, TypeI, Kind A, Form 5, Quality 911, Finish F2, is

on each side of the glass, with the lenses on oneside running at right angles to the other. Analternate design is a series of parallel rows ofcircular lenses one each side, with the centers of thelenses on one side halfway between centers of thelenses on the opposite side. Depending on themanufacturer's standards, circular lenses may bespaced ¼ or ½ inch on centers. This lens-type glassis especially desirable for use in borrowed-lightpartitions and in spaces where an even distributionof light in all parts of the room is necessary.

g. Colored Glass. Sheet glass, Type II, ClassI, Quality 95, is acceptable for use in the exteriorsashes of chapels. It is a hammered or figured-pattern sheet not less than c inch thick. Generally,it is amber in color. Several other colors are avail-able.

h. Shatterproof Glass. Shatterproof glass is in-

engine-test rooms, detention rooms, and otherplaces requiring a high resistance to breakage.Glass may be tempered or laminated, not less than¼ inch thick, and polished on both sides. Temperedglass is made by reheating the glass until it issomewhat soft, and then cooling it quickly in a bathof oil or against a metallic surface. It withstandsheavy impacts and great pressures, but acomparatively light blow with a pointed object onor near the edge may break it because of internalstresses resulting from sudden cooling. This type ofglass may fly apart violently when broken.Laminated glass gives protection against flyingpieces of broken glass. The glass is built up in themanner of a sandwich, with a sheet of transparentadhesive bond between two sheets of glass. If abreak occurs, the plastic stretches, serves as acushion, and holds the sharp fragments.

i. Insulating Glass. Double-pane and triple-pane insulating glass, each of the same nominalthickness, is separated by not less than / -inch3

16dehydrated airspace and hermetically sealed at thefactory, Dehydration should be guaranteed for aperiod of not less than 10 years. Glazing techniques


7-15

for insulating glass may be found in paragraph be used without cutting. Glass of special sizes is cut7.2.7.10. in the shop. For glass sizes, measure all four sides7.2.7.3 Putty. Putty for wood-sash glazing mustconform to current Federal Specification TT-P-00791. Types I and II may be used interchangeably,but Type II is recommended for filling holes andcracks where a harder material is desirable. Puttyand compound for metal-sash glazing mustconform to current Federal Specification TT-G-410. Types I and II are both suitable for interiorand exterior work. Type I is an elastic glazingcompound that dries on the surface but remainsslightly soft and plastic underneath. It is recom-mended for use, in addition to wood or metalbeads, on doors, transoms, and skylights, whererepeated shock or vibration may be encountered.Oil or other adulterants should not be added toputty or compound on the job. Putty or glazingcompound should be stocked in relatively smallquantities so that it will be fresh when used. A 30-day supply is suggested as sufficient for ordinaryinstallation needs. One gallon of putty orcompound will normally bed and face glazeapproximately 100 linear feet of ¾-inch rabbet, 150linear feet of ½-inch rabbet, or 200 linear feet ofd-inch rabbet.7.2.7.4 Glazier's Points and Clips. Glazier's pointsfor wood-sash glazing should be standard zinc tri- the surface clean with cloth saturated in mineralangles of approximately ½-inch equilateral. Wire spirits or turpentine, prime the putty runs, andslips for metal windows vary by type of window. A allow them to dry.reserve supply for maintenance work should beavailable at all times.7.2.7.5 Paint

a. General. Painting is mentioned here only toserve as a reminder that it must be accomplishedprior to glazing or reglazing. The selection andapplication of paints and other protective coatingsare covered in detail in a separate Tri-Services putty by scraping. Use steel wool or sandpaper tomanual, "Paints and Protective Coatings" (TM 5- remove rust. Clean the surfaces thoroughly with a618, NAVFAC MO-110, AFM 85-3). cloth saturated in mineral spirits or turpentine.

b. Wood-Sash Primer. Good maintenance andrepair practice requires that wood-sash glass d. New Metal Sash. Thoroughly clean the sashrabbets be primed or sealed before the glass is set. with a cloth saturated in mineral spirits or turpen-Shellac and quick-drying varnish should not be tine to remove dust, dirt, oil, or grease. Removeused as primers because they dry to hard glazed rust with steel wool or sandpaper. If the sash is notsurfaces that may prevent a tight putty bond. already factory-primed, prime it with rust-inhibitive

c. Wood-Sash Finish Paint. Surfaces of jambs,stop beads, and sashes in sliding contact may befinished with penetrating sealer in lieu of paint. exterior sash when the ambient temperature is 40E

d. Metal Sash. Metal should be cleaned andprimed before glazing or reglazing is done. Redlead-base, ready-mixed paint is suitable for touch-up or complete priming.7.2.7.6 Glasscutting. Insofar as possible, glassshould be purchased and stocked in sizes that can

of the sash and deduct / to c inch in the pane116

size for irregularities in the sash. Minimumequipment required for glasscutting consists of atable, a common wood or metal T-square, and aglasscutter. The table should be about 4 feet squarewith front and left edges square. Mark off thesurface of the table vertically and horizontally ininches. A thin coating of turpentine or kerosene onthe glass line to be cut is helpful in lubricating theaction of the cutter wheel. A sharp cutter must becarefully drawn only once along the line of thedesired cut. Additional strokes of the cutter mayresult in breakage. Allow about 5 percent forbreakage in cutting and setting. When extensivecutting is anticipated, a commercially manufacturedcutting board is available that incorporates theabove-mentioned minimal equipment plus a spring-loaded grip for the glasscutter that slides along thebar, assuring good, clean glasscutting. This boardis used in a vertical position and occupies very littlefloor space.7.2.7.7 Preparation Before Glazing.

a. Old Wood Sashes. Clean all putty runs ofbroken glass fragments and glazier's points.Remove loose paint and putty by scraping. Wipe

b. New Wood Sashes. Remove dust, prime theputty runs, and allow them to dry. All new woodsashes shall be pressure-treated for decay protec-tion (see Tri-Services manual, "Military Entomolo-gy Operations Handbook," Chapter 8, Section 5,NAVFAC MO-310, TM 5-632, AFM 91-16).

c. Old Metal Sash. Remove loose paint or

Prime bare metal and allow it to dry thoroughly.

paint and allow it to dry thoroughly.7.2.7.8 Setting Glass. Do not glaze or reglaze

F (4.5E C) or lower unless absolutely necessary.Sash and door members must be thoroughlycleaned of dust with a brush or cloth dampenedwith turpentine or mineral spirits. Lay a continuous/ inch thick bed of putty or compound in the116

putty run. See figure 7-8. The glazed face can be


7-16

recognized as the side on which the glass was cut. vertical. Press the glass firmly into place so that theIf the glass has a bowed surface, it must be set with bed putty will fill all irregularities.the concave side in. Wire glass is set with the twist

a. Glazier's Points. When glazing wood sash, wood or metal glazing beads bedded in putty.insert two glazier's points per side for small lights When setting wire glass for security purposes, setand about 8 inches apart on all sides for large wood or metal glazing beads, secured with screws,lights. When glazing metal sash, reuse the wire on the side facing the area to be protected. Woodclips or metal glazing beads. See figure 7-9. sash putty should be painted as soon as it has

b. Putty. After the glass has been bedded, laya continuous bead of putty against the perimeter ofthe glass-face putty run. Press the putty with aputty knife or glazing tool with sufficient pressureto insure its complete adhesion to the glass andsash. Finish with full, smooth, accurately formedbevels with clean-cut miters. Trim up the bed puttyon the reverse side of the glass. When glazing orreglazing interior sash and transoms, whether fixedor movable, and interior doors, use wood or metalglazing beads. Exterior doors and hinged transomsshould have glass secured in place with inside

surface-hardened. Do not wait longer than 2months after glazing. Metal sash, Type I, elasticcompound, should be painted immediately after afirm skin forms on the surface. Depending onweather conditions, the time for skinning over maybe 2 to 10 days. Type II, metal sash putty, canusually be painted within 2 weeks after placing.This putty should not be painted before it hashardened because early painting may retard the set.The paint should completely cover the putty andextend approximately c inch onto the glass surfaceto serve as a seal.


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7.2.7.9 Cleaning. Clean the glass on both sides commodate the size unit to be installed. Sufficientafter painting. A cloth moistened with mineral allowance must include a glazing leg minimum of ¾spirits will remove putty stains. Ammonia, acid inch.solutions, or water containing caustic soaps mustnot be used. When scrapers are used, care shouldbe exercised to avoid breaking the paint seal at theputty edge.

7.2.7.10 Insulating Glass. Two major types of in-sulating glass are currently manufactured which aredesigned to improve the U-value of the glass unit. d. A weep system should be incorporated intoThese are double- and triple-pane units with any insulating glass installation to drain excesshermetically sealed airspaces separating the panes. moisture away from the unit. Weep holes should beThe panes are separated by a dessicated spacer, a minimum d-inch thickness and installed three perwhich absorbs moisture from the airspace, and are unit.permanently sealed.

a. Preparation of sashes and frames should 10. The tape method utilizes a high-quality rubberfollow the same procedures outlined in paragraph material suitable for specific installations with a7.2.7.7. The sash must be of sufficient width to ac- release paper on one side. The tape is fitted to the

b. Two setting blocks spaced at the quarterpoints should be of neoprene or lead constructionwith manufacturer's recommended hardness andlength.

c. Unit must be installed square.

e. Glazing methods are illustrated in figure 7-


7-18

opening with corners butted, not overlapped, joints 7.2.8 Window Screens.sealed, and the paper removed just prior to instal-lation. Constant pressure is maintained against thetape from proper stop design. The tape and wetseal method utilizes the same procedure as the tapemethod except that a c-inch clearance is allowedbetween the top of the tape and the top of the stopwhich is filled with an elastomeric sealant ofpolysulfides, silicones, urethanes or acrylics. Theedge of the sealant should be leveled to improveweatherproofing. The wet glazing method requiresthe use of space shims on the face of the stops atintervals of 18 inches on center maximum. Thesealant is forced into the existing space using acaulking gun or power equipment. Putty andglazing compounds should not be used with insu-lating glass. Several structural glazing gaskets arealso available for installing insulating glass asshown in figure 7-10.

f. Glazing systems which apply pressure to theedge of glass for waterproofing should be main-tained at a pressure of 4 to 10 pounds per linearinch of perimeter or as recommended by the man-ufacturer. Avoid pressure on the marginal edge (c-inch) of the unit.

7.2.7.11 Safety Requirements. Handling and cut-ting glass creates a serious cutting hazard.Appropriate gloves and other personal protectiveequipment must be provided. Adequate proceduresfor the disposal of cuttings and broken glass shouldbe established.

Included in this category are half-length slidingwindow screens, full-length window screens, andfixed porch screens.

7.2.8.1 Screen Cloth. Mesh screening in currentuse is made of comparatively short-lived steel oriron wire, either painted or galvanized. Continueduse of such painted or galvanized screen cloth isnot recommended for other than planned, short-usebuildings. Do not use steel or iron wire screening intropical zones. The use of corrosion-resistantmaterial, such as copper, bronze, aluminum orplastic, is recommended for most screening needs.Bronze wire is recommended for installation inbarracks, dining facilities, and similar buildingswhere rough usage may be expected. Commercialbronze, better known as brass, is not recommendedfor use in areas subject to excessive condensationand salt air. Shipments of screening delivered onrequisitions for bronze should be tested to see thatbrass has not been substituted.

7.2.8.2 Wire and Mesh Sizes. The diameter ofmetal or plastic strands and the size of the openingsare important. Screen cloth having mesh openingsno larger than 0.0475 inch is recommended for allinstallations. Screen cloth suitable for mostlocations is the 18 x 18 mesh per inch made with0.011-inch-diameter strands. Screen cloth rec-ommended for tropical areas is type with the 0.015-inch-diameter strands, with opening sizes nogreater than 0.0475 inch.


7-19

7.2.8.3 Replacing Broken Screen Cloth. A too refastening of screening, or repainting. Whenlarge, free screen area is one of the causes of early screen is broken and replacement is necessary, cutscreen failure. A screen area between supports will a piece of screen cloth large enough to permitbe no more than 2 x 3 feet, if possible. Window tacking to frame. Tack new screening along onescreens eventually require repair of screen cloth, end completely, holding it tight as tacking


7-20

proceeds. Then tack opposite end, pulling wire traffic is heavy. Fasten wood or metal push-barsfrom end to end, as well as along the side which is approximately 45 inches above the floor. Hardwarebeing tacked. Finally, tack along other two sides cloth guards extend from lock rail to bottom railwhich should require practically no pulling. Do not and may be either ½-inch-square mesh, 19-gagepull mesh out of shape, and keep strands parallel to steel wire of 1-inch, diamond mesh woven from 16-sides of frame. Then replace molding which, when gage steel wire. Guards should be given blackfastened down firmly, takes up any remaining slack finish. They should be set close against the screenin the wire. Prompt repair of tear will often and firmly secured at all edges.preclude replacing entire screen. To repair a screen,cut a piece of screen cloth slightly larger than thetorn opening. Bring the edges of the tear back totheir original position as nearly as possible, andcover with the patch piece. Sew edges of patch toexisting screen with fine wire or monofilamentfishline.

7.2.8.4 Screen Protection. Push-bars and hardware cloth. If signs of rust or corrosion are detected,cloth guards are screen savers, especially where brush clean and apply a protective coating.

7.2.8.5 Screen Storage. Removable windowscreens should be taken down in the fall and storedin a dry place during the winter months. Do notstore screens on a concrete floor or on the ground.Inspect screen frames and screen cloth before plac-ing them in storage. Make necessary repairs andpaint frames. Patch or replace damaged screen

SECTION III—BUILDERS' HARDWARE

7.3.1 Metals and Finishes brass and bronze. However, castings are costly to

7.3.1. General. The composition of materials inbuilders' hardware is of fundamental interest. Itoften affects the ability of the product to maintainappearance and durability and can have an impor-tant bearing on the worth of a product under aparticular circumstance. Except for the few in-stances where plastics, woods, and ceramics areused, builders' hardware is made of metal. Selectionof the base metal and finish depends on suchfactors as use, exposure to elements, and appear-ance desired. Also, hardware in a room should har-monize in design and finish. In this discussion "basemetal," which is the material out of which the basicportions of the hardware item are manufactured, isdifferentiated from "finish," which denotes thesurface characteristics of the product. The finishmay be simply the result of treatment of the basicmetal, or it may be achieved by the addition of asecond metal or other product.

7.3.1.2 Base Materials. Basic metals used in build-ers' hardware are brass, bronze, iron, steel, stainlesssteel, aluminum, and zinc. Competition betweenproducers of the various metals, which may be cast,extruded, forged, or wrought, is frequently keen,especially with changes in production capacity andtechnology. Although not metal, plastics are beingused in a manner similar to a base metal inmanufactured hardware products.

a. Cast Metal. Cast metal is produced bypouring molten alloy into premolded forms. Thismethod results in a versatile shape which can bemachined, etched, or carved to yield a great varietyof designs. It is very durable, withstandsconsiderable abuse, and will take a fine finish in

produce and thicknesses are not as uniform asforging and extensions.

b. Extrudes. Extruded shapes are produced byforcing or drawing semimolten metal through dies,like a chef uses a pastry bag. Designs having linearcharacteristics are possible. Extrusions are verydurable but limited in application due to restrictionsof cross sections that can be designed or formed.Generally, extrusions are limited to brass andaluminum.

c. Forged Metal. Forged metal is hammered,pressed, or rolled into shape. A smooth, denseproduct results from this process, the value ofwhich relates to the thickness of the metal. Forgedmetal has considerable tensile strength due to theuniform denseness of the metal. It has excellentfinishing and machining capabilities. Many itemsthat were formerly cast are now forged. Materialwith thickness greater than 0.080 inch is acceptablein lieu of cast material.

d. Wrought Metal. Wrought metal is rolledinto flat sheets or stripes. The products are formedby punching or diecutting into the desired forms. Itmay be thick, as in a hinge, or thin, as in a push-plate.

e. Brass and Bronze. Brass and bronze aremetal alloys, the greatest portion of which arecopper and those containing smaller amounts ofother metals, notably lead and zinc. Bronze differsfrom brass in that it contains some tin. Differencesin color result from the proportions of the variousmetals included. Cast brass has a yellowish color,while cast bronze has a reddish hue.


7-21

f. Steel. Steel is widely used in builders' hard- American, hand-forged items. Iron forgings areware. It is stronger than iron. Ordinary carbon steel produced by hammering a red-hot bar of iron intocontains not only iron but portions of other the desired shape. Forged iron is almost pure iron,elements such as carbon, manganese, phosphorus, with only about 1 percent of other elements.and sulfur. Exposed to the weather, carbon steel islikely to rust. Its wide use results largely from itsstrength and lower cost. Most of the builders'hardware items made of wrought steel are formedin flat sheets by dies in heavy presses.

g. Stainless Steel. Stainless steel is an ironproduct of which there are about 40 standard types.Each contains substantial amounts of chromiumand small quantities of a number of other elements.A majority of types also contain appreciablepercentages of nickel. Because it is highly rust-resistant, has a higher luster finish, and is easilymaintained, stainless steel is prized as a builders'hardware material. The popularity of this metal hasincreased; most manufacturers now provide a largerange of stainless-steel products, such as locks, 7.3.1.3 Finishes. Natural finishes take the color oftrim, door-closure arms, butt hinges, kick plates, the base metal in the product and may be eitherpush- and pull-plates. It is very desirable when high or low luster. Applied finishes result from theextreme, rugged use is expected. addition by plating of a second metal, a synthetic

h. Aluminum. Aluminum is now in many waysin builders' hardware. It is usually alloyed with a. Finishes. Finishes for builders' hardwareabout 4 percent of other elements. Cast, forged, have undergone tremendous changes in recentand wrought products are obtained by much the years. New techniques and finishes have been intro-same processes as are other metals. Pressure-cast duced, changes in popularity have taken place, andaluminum is frequently used as a substitute for cast some finishes have been dropped. The preparationiron in miscellaneous items, such as door-stops, given base materials prior to finishing consistshandrail brackets, and hooks. generally of machining, buffing, and polishing.

i. Powdered Metal. Powdered metal ispressed into shape and then sintered in a furnace.For additional strength, it may be sintered again.The process is employed to form a range ofproducts from various metals..

j. Cast Iron. Cast iron's characteristics are its where natural oxidation of the entire exposedlong-wearing qualities, natural lubrication, brittle- surface yields the desired result. Oil rubbing ofness, low tensile strength, and tendency to rust. uncoated bronze produces a dark oxidized finishCast iron contains 92 percent iron and small quan- suitable for some decors. The chromiums, polishedtities of such other elements as carbon, manganese, and satin, are brass, bronze and nickel plating ofsilicon, phosphorus, and sulfur. The metal is poured builders' hardware has been done for scores ofinto sand molds to achieve the desired shape. years, usually by means of an electrolytic process.

k. Malleable Iron. Malleable iron is cast irontreated by baking or annealing to make it tough andshock-resistant. When properly cast and annealed, b. Coatings. Coatings are used to prevent tar-malleable iron can be bent and even knotted nishing or oxidation of plated brass and bronze fin-without breaking. Many manufacturers use ishes. The original color and sheen of naturalmalleable iron in items like pulls and closure arms metals can be maintained for a long time with theto reduce the possibility of breakage and provide use of modern, synthetic coating treatments.resistance to stress.

l. Forged Iron. Forged iron's greatest use in and uniform oxide on aluminum, giving it a hard,builders' hardware is in the manufacture of spe- tough skin. A variety of color anodized finishes,cialized or decorative trim often imitative of early- such as black and oxidized bronze, are available.

m. Zinc. Zinc has long been used in builders'hardware as a coating over iron and steel, since itresists rust. Many products are made using die-castzinc as a base metal. It is easily cast, machined, andplated.

n. Plastics. The rapid advance of plastictechnology has led to the development of durableand serviceable materials such as Bakelite, nylon,delrin, lexan, lucite, and formica. Although plasticsare becoming more widely used, they have manyshortcomings and are not as acceptable as metal.However, plastics have been successfully used forkick plates, mop plates, door-edging lockmechanisms, knobs, pulls, and hand levers.

enamel, or other material.

Polished brass and bronze finishes are produced bybuffing or polishing the metal to a high gloss beforeapplying a synthetic coating. Satin brass and bronzenatural finishes are obtained by dry-buffing orscouring, and the resultant finish is then coated.Uncoated finishes of brass or bronze are used

Oxidizing is also used, especially where the designsare ornamental.

c. Anodizing. Anodizing forms a protective


7-22

d. Finish Standards. Although the National 7.3.2.1 Universal. Used in any position (e.g., aInstitute of Science and Technology, U.S. Depart- surface bolt).ment of Commerce, some years ago prepared prod-uct standards for the finishes used with builders'hardware, the Door and Hardware Institute (DHI)has updated the standards, consistent with currentpractices in the industry. DHI Standard 1301,Finish Standards, lists 96 standard finishes and their 7.3.3 Hingesnearest U.S. equivalents. Samples of selectedstandard finishes may now be obtained from DHI.

7.3.2 Hands of Doors

The dictionary lists no less than 91 connotations ofthe word "hand." This well demonstrates the spe-cialized language of builders' hardware and theneed to understand the language. In the builders'hardware industry the position of the hinges on adoor, in terms of right or left, as viewed from theoutside of a building, room, or space to which thedoorway leads, determines the hand. The hand of adoor is a term used to indicate the direction of theswing of the door. See figure 7-11. The outside isthe side from which security is necessary. In aseries of connecting rooms (as in a hotel suite) theoutside will be the side of each successive doorapproached from the entrance. For two rooms ofequal importance with a passage between, the out-side is the passage side. Strictly speaking, the dooritself is only right or left hand; the locks and thelatches may be reverse bevel. However, it is neces- 7.3.3.2 Elements of Hinges. Swaging is a slightsary to include the term reverse and to specify in offset of the hinge at the barrel, which permits theaccordance with the conventions shown here. This leaves to come closer together and improves thewill prevent any confusion as to which side is the operation and appearance of the door. A leaf is oneoutside. This is especially important when different of the two attaching plates, which, when fastenedfinishes are desired on the opposite sides of the together by the hinge pin, form a complete hinge.door. Although the hardware items specified may Bearings (ball, oil-impregnated, or antifriction)be reversible, or even universal, it is good practice offer the highest qualities in ease of operation andto identify the hand completely, in accordance with durability. Nonrising pins are a feature of qualitythe convention here stated. For a person standing hinges. Close tolerances, especially in the pin,outside, the rule is that an inswinging door is prevent excessive wear, and are an importantregular bevel and an outswinging door is reverse characteristic of high-quality, heavy-duty hinges.bevel. Hardware in general may be: Hinges are available in brass, bronze, stainless steel,

7.3.2.2 Reversible. Hand can be changed by re-volving from left to right, or by turning upsidedown or by reversing some part of the mechanism(e.g., many types of locks and latches).

7.3.3.1 General. There are four basic applicationsof hinges: full mortise, half mortise, full surface,and half surface. See figure 7-12. Within each typethere are various styles, each designed for a par-ticular situation. In addition to these there are otherdesign types, such as olive knuckle, modernpaumelle and pivots. Hinges are further classifiedby such characteristics as mounting or movementcontrol. A butt hinge is a type designed for mortis-ing into the butt edge of the door and into therabbet of a door frame. A spring hinge contains oneor more springs to move the door into a closedposition. See figure 7-13. It may be either single ordouble acting. A checking floor hinge is a devicewhich combines top and bottom points for hangingthe door with a controlled-speed closing mecha-nism. Top, intermediate, and floor pivots makepossible installations to solve special design prob-lems and to enable transfer of weight from the jambto the floor.

and carbon steel.


7-23


7-24


7-25

7.3.3.3 How to Specify Hinges. Hinges are speci- their screw holes with doors and jambs, eitherfied by number (in pairs); either ball, oil-impreg- metal or wood, made by other manufacturers.nated, or antifriction bearings; type of tips; type ofscrews; type of hinge; metal; height-width (requiredonly for full mortise hinges); weight (standard orheavy); and finish. The number of hinges per doorvaries with the height of the door. Generally, aminimum of three per door is recommended, buttwo may suffice for doors to 5 feet high. Three arerequired for doors up to 7 feet 6 inches high. Oneadditional hinge is required for every additional 30 7.3.3.5 Size and Gage. It is important that the sizeinches. Template hinges are made to standard of the hinge and the gage of metal are adequate fortemplates (in accordance with Government the job and are consistent with the size, weight, andstandards) to insure exact matching of hinges and frequency of use of the door. In sizing hinges, the

7.3.3.4 Screws and Fastenings. It is the custom tosupply as regular packing all machine screws andwood screws or combination screws which can beused with both wood or metal. Through-bolts andgrommet nuts, where so indicated, are furnishedregularly for application of half-surface or full-sur-face door leaf, along with machine screws for jamb.


7-26

first dimension is that taken at the leaf. This is the door to hold the lock body and the other in thevertical height of the hinge, which is the first edge of the door to receive the latch mechanism.numeral on full-mortise hinges, not including the When these two are joined together in the door,tip. Table 7-1 provides a helpful tabulation for they comprise a complete latching or lockingdetermining size and gage. mechanism. Bored-type locks have the keyway

TABLE 7-1. — HINGE GUIDE

DoorMinimum Hinge

Height (in)Thickness (in) Width (in)

f or 1 . . . . . . . Any . . . . . . . . . . 2½.1c . . . . . . . . . . To 36 . . . . . . . . 3.1d . . . . . . . . . . To 36 . . . . . . . . 3½. 1d . . . . . . . . . . >36 . . . . . . . . . . 4.1¾ . . . . . . . . . . To 41 . . . . . . . . 4½ 1¾ . . . . . . . . . . > 41 . . . . . . . . . 4½ Heavy.1¾ to 2¼ . . . . . Any . . . . . . . . . . 5 Heavy.

Use proper width of hinge if trim clearance isrequired. Hinges should be heavy weight for heavydoors or doors of high frequency and unusualstress. Heavy-weight hinges should have a mini-mum width of 4½ inches when used for doors 1¾inches thick. On all exterior doors opening out andreverse bevel interior doors with locks, a pin whichcannot be removed when the door is closed or aninterlocking leaf feature should be specified. Ball,oil-impregnated, or antifriction bearing hingesshould always be specified for doors equipped withdoor closures.

7.3.4. Locks

7.3.4.1. General. One of the most importantcategories of builders' hardware is locks. Thenames used for locks were originally selected toidentify either the type of construction orinstallation. Considering the great variety offunctions, types, sizes, weights, security andconvenience features of locks, considerableexperience is fully required to select the properlock for a particular use. The locks most commonlyused in all types of construction are describedbelow. See figure 7-14.

7.3.4.2. Bored Type. These types of locks are in-stalled in a door having two round holes at rightangles to one another, one through the face of the

(cylinder) and locking device, such as push or turnbuttons, in the knobs. They are made in threeweights-heavy, standard, and light duty. The as-sembly must be tight on the door, without exces-sive play. Knobs should be held securely in placewithout screws and a locked knob should be re-movable. Roses should be threaded or securedfirmly to the body mechanism. The trim has im-portant effects in this type of lock, because work-ing parts fit directly into the trim. Regular back-setfor a bored lock is usually 2¾, but it may vary.

7.3.4.3. Preassembled Type. The preassembled-type lock is installed in a rectangular notch cut intothe door edge. This lock is one that has all the partsassembled as a unit at the factory, and wheninstalled little or no disassembly is required.Preassembled-type locks have the keyway (cylin-der) in the knobs. Locking devices may be in theknob or on the rose or excutcheon. Regular back-set is 2¾ inches. The lock in available only isheavy-duty weight.

7.3.4.4. Mortise type. A mortise lock is installed ina prepared recess (mortise) in a door. The workingmechanism is contained in a rectangular-shapedcase with appropriate holes into which the requiredcomponents, cylinder, knob and turn-piece spindlesare inserted to complete the working assembly.Regular backset is 2¾ inches. These locks areavailable in heavy-duty and standard-duty weight.Armored fronts are available. In order to provide acomplete working unit, mortise locks, except forthose with deadlock function only, must beinstalled with knobs, levers, and items of trim.

7.3.4.5. Integral Type. An integral lock is a mor-tise lock with a cylinder in the knob. It is installedin a prepared recess (mortise) in a door. A com-plete working unit consists of the lock mechanismand selected trim (knob, rose, escutcheon). Rosesor escutcheons are bolted together through the lockcase. Regular backset is 2¾ inches. This type isavailable only in heavy-duty weight.


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7.3.4.6 Details. b. Latchbolts. The function of a latchbolt is to

a. Bolts. The lock achieves its function bymeans of various types of bolts. The bolt is a bar ofmetal, which projects out of the lock into a strikeprepared to receive it.

hold the door in a closed position. A latchbolt isspring actuated and is used in all swinging-doorlocks except those providing dead-bolt functiononly. It has a beveled face and may be operated bya knob, handle or turn. It is recommended for the


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heavy-duty bored, mortise, preassembled, and inte- so that the latchbolt will not hit the doorjambgral types that some kind of antifriction provision before the strike. A wrought box should be in-be incorporated. The throw of the latchbolt must stalled back of the strike in the jam. This box willnot be less than ½ inch. "Throw means the protect the boltholes from the intrusion of plasterprojection of the latchbolt beyond the lock face. construction debris or other foreign material, whichFriction occurs when a latchbolt hits the lip of the would prevent the bolt from projecting properlystrike. An antifriction feature is recommended to into the strike. Standards covering installationinsure easy closing of the door. This is particularly dimensions for locks have been issued by thedesirable when door-closing devices are used. This American National Standards Institute. Thesedevice may be a split latchbolt, a plastic insert in include dimensions for strikes, the use of whichthe bolt or in the strike, a pivoted bolt, or a self- provides uniformity in frame preparation.lubricating bolt.

c. Auxiliary Deadlatch. An auxiliary deadlatch device which replaces an ordinary strike and makesis a security feature and should be required on all possible remote electric locking and unlocking of alocks used for security purposes, unless a dead-bolt door. A control mechanism actuates the electricfunction is specified. This feature deadlocks the strike and allows the door to be opened andlatchbolt automatically and makes it virtually im- relocked without a key. Optional features availablepossible to depress the latchbolt when the door is include accommodation for dead bolt, automaticclosed. unlocking if power fails, and built-in provision to

d. Dead bolt. A dead bolt is a bolt having nospring action and is activated by a key or by a turn.It must be manually operated. Dead bolts providesecurity. When hardened steel inserts are used, the g. Cylinders. The cylinder of a lock is thesecurity is greater. The minimum throw should be cylindrical-shaped assembly containing a tumbler½ inch. A dead bolt may be specified with certain mechanism and the keyway, which can be actuatedfunctions or mortise, preassembled, and integral only by the correct keys. For servicing, such aslocks. keying, all cylinders may be removed. In some

e. Lock Strikes. A lock strike is a metal platemortised into the doorjamb to receive and to holdthe projected latchbolt. It is sometimes called a"keeper." The proper length lip should be specified

f. Electric Strike. This is an electromechanical

indicate the door is not locked. There are variousdesigns of electric strikes for use with numeroustypes of locks and exit devices.

types it is also possible to remove the keyway as-sembly but only by means of a control key. To pro-vide greater security, special cylinder collars areavailable.

SECTION IV—MAINTENANCE AND REPAIR OF HARDWARE

7.4.1 Bolts and Screws coat of oil applied. The same procedure applies to

All bolt and screw heads should be carefully in-spected, and any that show rust discoloration orrust scale should be thoroughly wire-brushed. Ifany bolts or screws have corroded to the extentthat they lack good fastening strength, they shouldbe removed and replaced. When the holes wherebolts or screws are removed are too large for newfasteners, new holes should be drilled and new fas-teners of the drive-screw or self-tapping type pro-vided in an adjoining solid portion of the metal.

7.4.2 Door and Window Hardware operation as well as shortening the life of the

Interior and exterior hinged, sliding, and rollingdoors of every type, including storm and screendoors, should be checked for faulty installation andlack of maintenance. The operation and conditionof hinges, lock assemblies, closers, tracks, hangers,and other hardware items should be checked. Ifparts are rusted, they should be cleaned and a light

the mechanical operator for monitor sash andskylights. Available keys should be fitted for properlock operation. Brass and bronze surface plates andknobs should be cleaned as described in paragraph7.4.11.

7.4.3 Door-Closing Devices

The first thing to check on any closing device isproper installation according to the manufacturer'sinstruction sheet. Often closers are applied too nearor too far from the hinge jamb, which affects

closer. It is imperative that the closer and its arm bein their correct places and firmly fastened. Fa-miliarization with the adjustment features of thedevices to be maintained is necessary for a properunderstanding of their functions. The manufactur-er's instruction sheet should be valuable for this.Closing devices that have hydraulic controllingaction, such as liquid door closers and checking


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floor hinges, must be refilled with the correct type the interlock. Replacement thresholds shouldof fluid at regular intervals. Keeping closers full of always be placed in new caulking bases.liquid is one way to prolong their lives as well asinsure smooth operation. Finally, all closing devicesshould be overhauled periodically, which involvescomplete disassembly and cleaning in the shop.Floor-type closers for exterior doors in locationssubject to ice and snow are usually difficult tomaintain and should always be installed on theinside of outswinging doors. To simplifymaintenance, concealed-type door closers shouldbe limited to locations where they are necessary foroperational reasons.

7.4.4 Locksets

The basic function of a lockset is to lock or latch adoor in its closed position; therefore, the first orderof maintenance should be to determine whether thelock is in alignment with its strike. The latch-boltshould set easily into the strike without any bindingor scraping. The dead bolt, when projected byaction of key or turn, should also seat withoutcutting away wood or other material behind thestrike. In the operation of knobs, set screws mustbe tight. Before tightening, however, the knobaction should be tested to see if it is free. If not, thesetscrews should be loosened in the shank andknob turned counterclockwise, just enough topermit easy action without binding. Then the set-screws should be retightened. Make sure they bearagainst a flat side of the spindle rather than on acorner. If the knobs have "screwless" or "clutch"fastenings, a spanner wrench will be needed tomake adjustments. The wrench should be used toloosen the inside knob shank, and this knob or itsshank component threaded up or down the spindle,depending on the adjustment necessary. Thelubricating agent for locks and cylinders is drygraphite. Do not use grease or oil. To free gummedor corroded parts, kerosene or penetrating oil maybe used, but this should be allowed to evaporatebefore reassembly. Bored or unit types of locksetsrepresent a somewhat different problem in that theyhave knobs and roses assembled in an integral partof the lock mechanism. Adjustment features differgreatly among the various makes; therefore, it isrecommended that the manufacturer's instructionsbe consulted before any attempt is made to correctpoor installations.

7.4.5 Thresholds

Loose fastenings are often a source of trouble withthresholds. At each inspection, screws should betightened, and loose anchors and expansion shieldsreplaced. Check for dirt and gravel, particularly ininterlocking types. The door strip should be set in

7.4.6 Sliding-Door Equipment

The various types of hangers have both vertical andlateral adjustment. Find how these work andconsult the manufacturer's specifications to attainthe utmost efficiency in keeping the doors slidingeasily. Bottom tracks and guide channels should bekept free of debris.

7.4.7 Panic-Exit Devices

Particular care must be taken to insure proper op-eration of exit devices. Under no circumstancesshould bars, chains, padlocks, or auxiliary locks beused on exit doors. Familiarization with these de-vices will enable personnel to keep them function-ing to lock against ingress while still permittingunimpeded egress. This involves keeping strikesaligned and free of debris so that latches will hold.Crossbars that are loose or flabby in action indicatethat service is needed. Check for worn springs,pivots, or spindles. When astragals are present,they should be adjusted to keep center clearance ata minimum. See discussion of fire doors, paragraph7.1.6.

7.4.8 Security Fences and Gates

To maintain stability and to correct alignment,connections for gates, posts, braces, guys, andanchor on security fences should be tightened.Hinges, latches, locking devices, and other hard-ware should be cleaned and lubricated for easy op-eration.

7.4.9 Skylights

Skylights made of multiple supporting membersand panes are often a source of leaks. As a rule,maintenance consists only of replacing sealingstrips, cushion strips, and skylight compound atjoints between glass sheets. When glass, metalflashings, and joint cappings must be replaced, ma-terials and methods should be similar to those usedin the original installation. Wood or steel structuralframe members that have deteriorated should bereplaced.

7.4.10 Vents

Metal vents should be inspected for deteriorationcaused by lack of protective paint or inadequatepaint coverage. Vents should not be exposed tostanding water. They should be equipped with aflashing flange to prevent early flashing failurebecause of expansion and contraction of the vents.For metal flashing, roof-drainage devices, gravel


7-30

stops and edge strips, see Tri-Services manual, surface should be cleaned with a solvent-type"Maintenance and Repair of Roofs," (TM 5-617, cleaner. For good lacquer adhesion, it is preferredNAVFAC MO-113. AFP 91-31, MCO P11014.9). that a good "tooth" on the surface be attained by

7.4.11 Cleaning and Maintenance of Aluminum

7.4.11.1 For routine cleaning of aluminum, themildest method will usually work easily and well.However, conditions vary, and if the surfaces havebeen neglected for a long time, it may be necessaryto experiment with small areas before selecting amethod. Three methods of routine cleaning are:

a. Wash with clean water and dry thoroughly.Wash with a synthetic detergent cleaner, rinse, anddry. Use a nonetching chemical cleaner accordingto the cleaner manufacturer's directions.

b. If the aluminum has accumulated a thickcoating of dirt, it is usually easier to remove the Natural brass and bronze finishes age quite well andheavy dirt with a solvent cleaner. Then try one of contribute to the beauty of a building. No attentionthe following operations: a wax-base polish cleaner to this hardware is required other than wiping itwith a clean, soft rag or pad, following the manu- with a damp cloth until the original lacquer beginsfacturer's directions; a nonwax-base polish cleaner to wear off. When abrasion of the lacquer becomeswith a clean, soft rag or pad, following manufac- apparent, the best appearance will be achieved byturer's directions; or a mild abrasive cleaner use of a lacquer thinner or some nonacid agent to(scouring powder) on a damp, clean cloth. Rinse remove all remaining lacquer coating. Then thewell and dry after any of these operations. piece may be polished with brass polish. In time,

c. If the results of methods (a) and (1)) areunsatisfactory, use a stainless-steel wool pad of finetexture with a liquid wax or one of the cleaners 7.4.13 Miscellaneousmentioned under method (b). Mild steel wool canalso be used; however, any remaining particles willrust-stain the aluminum and should be removed.

7.4.11.2 In the process of waxing aluminum, thealuminum should be cleaned thoroughly with asolvent cleaner. The wax should be applied with asoft, clean cloth; polishing should be done with an-other soft cloth. Before lacquering an aluminumsurface, old lacquer that is worn off in spots shouldbe stripped completely with a lacquer remover. The

using an etching type of cleaner. After 3 to 5minutes, the surface should be rinsed with cleanwater, and then a thorough wet coat of lacquerapplied by paint spray equipment, if available.Otherwise, a clean paintbrush should be used, andthe lacquer thinned as the manufacturerrecommends. The first coat should be allowed todry, and then a second coat applies in the samemanner. To protect aluminum from stains and otherdamage, the use of strong cleaners should beavoided and the aluminum padded against scrapingor denting by heavy loads.

7.4.12 Brass and Bronze Finishes

the latter will impart an attractive, soft luster,characteristic of old brasses and bronzes.

There are many types of builders' hardware itemsnot specifically mentioned in this manual. All ofthem must be examined periodically if they are tofunction properly. Tight fastenings and proper lu-brication will keep most of them working. The ap-plicable hardware manufacturer's instructions forassembly and parts should be available for theproper maintenance of hardware items.


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APPENDIX A

REFERENCES

Government Publications29 CFR 1910.1001 Public Law—Code of Federal

Regulations, Title 29, Part 1910 1001.Department of Defense Manuals

DOD Construction Criteria Manual 4270.1 MTri-Services Manuals

TM 5-609, NAVFAC MO-125, AFP 91-2 . . . . Military Custodial ServicesTM 5-617, NAVFAC MO-113 and MCO

P11014.9 AFP 91-31. . . . . . . . . . . . . . . . . . Maintenance and Repair of RoofsTM 5-622, NAVFAC MO-104, AFP 91-34 . . . Maintenance of Waterfront StructuresTM 5-618, NAVFAC MO-110 AFP 85-3 . . . . . Paints and Protective CoatingsTM 5-632, NAVFAC MO-310 AFP 91-16 . . . . Military Entomology Operational HandbookTM 5-624, NAVFAC MO-102 AFP 85-8 . . . . . Maintenance and Repair of Surfaced AreasTM 5-695, NAVFAC MO-117 AFP 91-37 . . . . Maintenance of Fire Protection System

Department of Navy Technical PublicationsNAVFAC Design Manual 14.2 . . . . . . . . . . . . . Carpet Selection Guide

Department of Air Force Technical PublicationsAir Force Design Manual . . . . . . . . . . . . . . . . . Interior Finish Materials

Federal SpecificationsAA-L-30 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . Gypsum BoardAA-V-00200B . . . . . . . . . . . . . . . . . . . . . . . . . Venetian BlindsCS-35-61 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . PlywoodDD-G-1403 . . . . . . . . . . . . . . . . . . . . . . . . . . . Glass Plate (Float), Sheet Figured and Spandrel Heat-

Strengthened and Fully Tempered)HH-R-590 . . . . . . . . . . . . . . . . . . . . . . . . . . . . Roofing Felt (Asbestos, Asphalt-Saturated)HH-R-595 . . . . . . . . . . . . . . . . . . . . . . . . . . . . Roofing Felt, Coal-Tar and Asphalt-Saturated

Organic Felts, RollsLF-475 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . Floor Covering, VinylL-F-1641 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . Floor Covering, Sheet VinylLLL-B-810 . . . . . . . . . . . . . . . . . . . . . . . . . . . . Building Board, (Hardboard) Hard Pressed, Vegeta-

ble FiberLLL-F-1238A . . . . . . . . . . . . . . . . . . . . . . . . . . Floor Covering LinoleumMMM-A-110 . . . . . . . . . . . . . . . . . . . . . . . . . . Adhesive Asphalt, Cut-Back Type (for Asphalt and

Vinyl Asbestos Tile)MMM-A-115 . . . . . . . . . . . . . . . . . . . . . . . . . . Adhesive, Asphalt, Water-Emulsion Type (for Asphalt

and Vinyl Asbestas Tile)MMM-A-001993 . . . . . . . . . . . . . . . . . . . . . . . Adhesive, Epoxy, Flexible Filled for Binding Scaling

and GroutingO-C-114 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . Calcium Hypochlorite, TechnicalO-S-602 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . Sodium Hypochiorite SolutionO-S-642 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . Sodium Phosphate, Tribasic, Technical, Anhydrous,

Dodecahydrate adn MonohydrateP-P-101 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . Paper Abrasive, Silicon Carbide, WaterproofP-P-l05 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . Paper Abrasive, FlintP-P-121 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . Paper Abrasive, GarnetP-S-865 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . Oil and Water Absorbing CompoundsPS-1-66 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . PlywoodP-W-155 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . Wax, Floor, Water Emulsion: w/gpl SupplementsQQ-L-101 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . Lath, Metal, (and Other Metal Plaster Bases)


A-2

QQ-S-698 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . Steel, Sheet and Strip, Low CarbonQQ-S-700D . . . . . . . . . . . . . . . . . . . . . . . . . . . Steel Sheet and Strip, Medium and High CarbonR-P-381 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . Ptich, Coal-Tar: (for) Aggreate-Surfaced Built-up

Roofing, Waterproofing, and DampproofingSS-A-666 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . Asphalt, Petroleum (Built-up Roofing, Waterproof-

ing, and Dampproofing)SS-A-694 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . Asphalt, Petroleum (Coating, Brushing and Spraying

Consistency)SS-A-701 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . Asphalt, Petroleum (Primer, Roofing and

Waterproofing)SS-B-755 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . Building Board, Asbestos-Cement: Flat and Corru-

gatedSS-C-153 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . Cement Bituminous Plaster Type-i, with Asphalt

Saturated Felts and Type II with Coal-Tar SaturatedFelts

SS-C-161A . . . . . . . . . . . . . . . . . . . . . . . . . . . . Cement: Keen'sSS-L-30D . . . . . . . . . . . . . . . . . . . . . . . . . . . . . Lath, and Board Products, GypsumSS-L-351 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . Lime: Hydrated (For) Structure PurposesSS-R-501 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . Roofing Felt, Asphalt-Prepared, Smooth SurfacedSS-S-118A . . . . . . . . . . . . . . . . . . . . . . . . . . . . Sound Controlling Blocks and Boards (Prefabricated

Acoustical Tiles and PanelsSS-S-200D . . . . . . . . . . . . . . . . . . . . . . . . . . . . Sealing Compounds, two component, Electronic,

Polymer Type, Jet Fuel Resistant, Cold AppliedSS-S-1401 . . . . . . . . . . . . . . . . . . . . . . . . . . . . Sealing Compound, Hot Applied, For Concrete and

Asphalt PavementsSS-S-1614 . . . . . . . . . . . . . . . . . . . . . . . . . . . . Sealing Compound, Jet Fuel Resistant, Hot

Applied,One Component, For Portland Cement andTar Concrete Pavements

SS-T-312 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . Title, Floor: Asphalt, Rubber, Vinyl, Vinyl AsbestosTT-C-598 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . Calking Compound, Oil and Resin Base Type (For

Masonry and Other Structures)TT-F-336 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . Filler, Wood PasteTT-G-410 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . Glazing Compound, Sash (Metal) for Back Bedding

and Face Glazing (not for Channel Stop Glazing)TT-P-00791 . . . . . . . . . . . . . . . . . . . . . . . . . . . Putty: Pure Linseed Oil (for Wood Sash Galzing)TT-R-251 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . Bemover, Paint (Organic Sovent Type)TT-S-176 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . Sealer, Surface-Varnish Type, Floor, Wood and CorkZZ-M-71d . . . . . . . . . . . . . . . . . . . . . . . . . . . . Sheeting, RubberZZ-M-71E . . . . . . . . . . . . . . . . . . . . . . . . . . . . Matting, Rubber and Vinyl

Department of Defense SpecificationsDOD-C-2687B . . . . . . . . . . . . . . . . . . . . . . . . . Notice 1, Compound, Battery Sealing (Metric)

Military SpecificationsMIL-L-14519C . . . . . . . . . . . . . . . . . . . . . . . . . Limestone, PulverizedMilitary StandardsMIL-STD-865A . . . . . . . . . . . . . . . . . . . . . . . . Notice 2, Selective (Brush Plating) Electrodisposition

US. Department of Commerce, Product SpecificationsPS 1-74 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . Construction and Industrial PlywoodPS51-71 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . Hardwood and Decorative Plywood


A-3

U.S. Department of Interior PublicationsConcrete Manual, Bureau of Reclamation

General Services Administration PublicationsA-A-373A . . . . . . . . . . . . . . . . . . . . . . . . . . . . Glazing Compound, Sash (Metal) for Back Bedding

and Face Glazing (Not for Channel or Stop Glazing)Non-Government Publications

American Society for Testing and Materials(ASTM), 1916 Race Street, Philadelphia, PA19103ASTM C-28-80 . . . . . . . . . . . . . . . . . . . . . . . . . . Specification for Gypsum PlasticASTM C-33-80 . . . . . . . . . . . . . . . . . . . . . . . . . . Specification for Concrete AggregatesASTM C-36-80 . . . . . . . . . . . . . . . . . . . . . . . . . . Specification for Gypsum WallboardASTM C-67-81 . . . . . . . . . . . . . . . . . . . . . . . . . . Brick and Structural Clay Title, Sampling and Test

ingASTM C-94-80 . . . . . . . . . . . . . . . . . . . . . . . . . . Specification for Ready-Mixed ConcreteASTM C-144-76 . . . . . . . . . . . . . . . . . . . . . . . . . Specification for Aggregate for Masonry MortarASTM C-208-72 . . . . . . . . . . . . . . . . . . . . . . . . . Structural Insulating Board Made from Vegetable

FibersASTM C-220-77 . . . . . . . . . . . . . . . . . . . . . . . . . Specification for Flat Asbestos-Cement SheetsASTM C-270-80a . . . . . . . . . . . . . . . . . . . . . . . . Specification for Mortar for Unit MasonryASTM C-631-70 . . . . . . . . . . . . . . . . . . . . . . . . . Specification for Bonding Compounds for Interior

PlasteringASTM C-669-75 . . . . . . . . . . . . . . . . . . . . . . . . . Specification for Glazing Compounds for Back Bed

ding and Face Glazing Metal SashASTM C-840-79 . . . . . . . . . . . . . . . . . . . . . . . . . Specification for Application and Finishing of

Gypsum BoardASTM C-881-78 . . . . . . . . . . . . . . . . . . . . . . . . . Epoxy-Resin Base Bonding System for ConcreteASTM D-41-78 . . . . . . . . . . . . . . . . . . . . . . . . . . Primer for use with Asphalt in Dampproofing and

WaterproofingASTM D-43-73 . . . . . . . . . . . . . . . . . . . . . . . . . . Specification for Cresosote for Priming Coat with

Coas-Tar Ptich in Dampproofing and Waterproofing

ASTM D-173-80 . . . . . . . . . . . . . . . . . . . . . . . . . Specification for Woven Cotten Fabric Saturatedwith Bituminous Substance for Use inWaterproof ing

ASTM D-226-77 . . . . . . . . . . . . . . . . . . . . . . . . . Asphalt-Saturated Roofing Felt for Use in Water-proofing and in Constructing Built-up Roofs

ASTM D-312-78 . . . . . . . . . . . . . . . . . . . . . . . . . Asphalt for use in Constructing Built-up RoofCover- age. Type Depending on Slope of Roof

ASTM D-449-73 . . . . . . . . . . . . . . . . . . . . . . . . . Specification for Asphalt Used in Dampproofingand Water Proofing

ASTM D-450-78 . . . . . . . . . . . . . . . . . . . . . . . . . Specification for Coal-Tar Pitch for Roofing,Damp- proofing and Waterproofing

ASTM D-1187-66 . . . . . . . . . . . . . . . . . . . . . . . . Specification for Asphalt Base Emulsions for Useand Protective Coating for Metal

ASTM D-1327-78 . . . . . . . . . . . . . . . . . . . . . . . . Specification for Bitumin-Satruated Woven BurlapFabrics Used in Roofing and Waterproofing

ASTM D-1668-80 . . . . . . . . . . . . . . . . . . . . . . . . Specification for Woven Glass Fabric Treated withBituminous Substance for Use in Waterproofing

ASTM D-1751-73 . . . . . . . . . . . . . . . . . . . . . . . . Specification for Preformed Expansion Joint Fillersfor Concrete Paving and Structural Construction(Nonextruding and Resilient Bituminous Types)


A-4

ASTM D-1752-67 . . . . . . . . . . . . . . . . . . . . . . . . Specification for Preformed Sponge Rubber andCork Expansion Joint Filler for Concrete Paving and Structural Construction

ASTM D-1850-74 . . . . . . . . . . . . . . . . . . . . . . . . Specification for Concrete Joint Sealer, Cold-Application Type

National Fire Code StandardsNational Fire Protection Association,Batterymarch Park,Quincy, MA 02269

1 . . . . . . . . . . . . . . . . . Fire Prevention Code80 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . Fire Doors and Windows

220 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . Standard Types of Building Construction252 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . Fire Doors

NFPA PublicationsNational Forest Products Association, 1619 Massa

chusetts Ave., NW., Washington, DC 20036 National Design Specification for Wood Con struction Design Values for Wood Construction

PCA PublicationsPortland Cement Association Publications, Old Or

chard Road, Skokie, IL 60076ACI-318 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . Building Code Requirements for Reinforced Concrete

DHI PublicationsDoor and Hardware Institute, 7711 Old Springh

ouse Road, McLean, VA 22102DHI-1301 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . Finish Standards

Shell Chemical Co. PublicationShell Chemical Co., P.O. Box 2463, Houston, TX

77002SC 106-84 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . Recommendations for Handling Resins and Auxilia-

ry ChemicalsJohn Wiley and Sons PublicationsJohn Wiley and Sons., Inc., 605 3rd Avenue, New

York, NY 10158"Building Construction, Materials and Types of

Construction" by Whitney Clark Huntingtonand Robert E. Mickadeit.

F. G.MA. PublicationsFlat Glass Marketing Association, 3310 Harri

son Street, Topeka, KS 66611.


B-1


B-2


B-3


C-1

APPENDIX CExample of Typical Cost Analysis

This appendix provides a method for evaluating alternative throughout the useful life of that alter-the economic advantages of using one material native. Life cycle costs can be compared byand/or method in lieu of others. The approach equating all costs to their present value cost.presented here may be used, with little When comparing life cycle costs, care must bemodification, to evaluate the relative economic taken that the life cycle considered is for the sameadvantages of any selection of building or length of time for each alternative and does notstructure maintenance alternatives. exceed the expected retention time for that

facility.This example analysis is a life cycle cost study ofpainting existing wood siding versus overlayingexisting siding with new prefabricated siding andinsulation. It is divided into four parts. ParagraphC.1 discusses general factors impacting on thestudy. Paragraph C.2 compares continuing thepresent system, but with insulation added to theoutside and protected by new siding-any kind ofsiding. Paragraph C.3 compares four types offactory prefinished siding with sufficientinsulation added to provide each type with thesame degree of thermal energy conservation.Paragraph C.4 provides the cost data source forall the figures used in C.2 and C.3 and a genericdescription of the four fictional materials used assiding overlayment.

C.l General

C.1.1 PurposeTo provide an evaluation of the economic advan-tages of installing new exterior prefabricatedsiding and insulation over wood siding in lieu ofrepainting the existing wood siding.

C.l.2 Consideration of Useful LifeOnly those maintenance alternatives which havea useful life shorter than, or equal to, theremaining useful life of the structure should beevaluated. Generally, major repairs should beaccomplished on only those facilities identified onthe approved installation master plan as beingapproved for long-term retention and utilization.

C.1.3 Estimating Useful LifeThe estimate of remaining useful life should bebased on sound engineering judgment consideringthe total facility, including all necessary structur-al, mechanical, and functional elements necessaryto realize the remaining useful life.

C.1.4 Life Cycle CostingLife cycle costing is the evaluation of the total ofall costs and savings identified with a particular

C.1.5 Present Value CostPresent value cost is the sum of money that willgrow at a prescribed interest rate to either aspecified sum in one particular year or will growto annual equal expenditures over a specifiednumber of years. It is the amount of money, ifput into an interest-bearing account, will be justsufficient to cover each cost as the cost arises.The account's rate of interest would be thecurrent discount rate adjusted by the projectedrate of inflation. The discount rate is prescribedby the appropriate regulation for each service,and is used at 10 percent in the examples thatfollow below.

C.l.6 Selection of AlternativeThe alternative with the lowest present value cost,including any initial cost, is the most economical.A final selection based upon features notexpressible in monetary terms and not shown tobe most economical must be justified.

C.1.7 Estimating CostsCost estimates for life cycle costing should bemade using known comparable costs wheneverpossible. These may be obtained from localfacility records, records at other facilities, highercommands, and current commercially publishedand nationally recognized estimating manuals.The source of all cost estimates should bedocumented and cost estimate computationsshould be included with the cost analysis.

C.1.8 Recurring CostsAll costs recurring annually or at intervals mustbe escalated to the time expenditure is made.Energy Conservation Investment Program proce-dures and other regulations provide guidance forescalation rates of usual construction, mainte-nance and repair costs, and energy types. Energyescalation costs vary depending on the energysource (see table C-1).


C-2

TABLE C-1. — Escalation Rates The accumulative total cost shown in the second

Type (pct)Rate

Coal . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 5.0Fuel Oil . . . . . . . . . . . . . . . . . . . . . . . . . . . 8.0Natural or Liquid Petroleum Gas . . . . . . . . . . . 8.0Electricity . . . . . . . . . . . . . . . . . . . . . . . . . 7.0

The escalation rate and discount rate are com-bined into cost factors in table C-2. Costsrecurring at intervals must use the "one-timecost factors" in the first column of each table.

column may be used when the basic cost itemoccurs each year. In the absence of betterinformation, escalation rates for replacement,repair, and maintenance costs may be taken at 5percent. If any future costs are forecast bymore accurate means, such as an appropriateregulation, the present value is obtained byusing the estimated future cost and the 0 percentrate as shown in table C-2 Rate A. In all fourtables in table C-2, the discount rate is 10percent.

Table C-2 — Differential Escalation Discount Factors

The one-time cost factors are likely to be applied to one-time costs occurring in isolated years after the program year.Recurring benefits/cost factors are to be applied to identical annually recurrent cash flow. * These factors are to be applied tocost elements which are anticipated to escalate at the same rate as the general price level.

Economic life Differential inflation rate—0%* Discount rate—10% Differential inflation rate—5%* Discount rate—10%years

Rate A Rate B

One-timecost factors One-time cost factorsRecurring benefits/cost Recurring benefits/costfactors factors

1 . . . . . . . . . . . . . . . 0.954 0.954 0.977 0.9772 . . . . . . . . . . . . . . . 0.867 1.821 0.933 1.9103 . . . . . . . . . . . . . . . 0.788 2.609 0.890 2.8004 . . . . . . . . . . . . . . . 0.717 3.326 0.850 3.6505 . . . . . . . . . . . . . . . 0.652 3.977 0.811 4.4616 . . . . . . . . . . . . . . . 0.592 4.570 0.774 4.4617 . . . . . . . . . . . . . . . 0.538 5.108 0.739 5.9748 . . . . . . . . . . . . . . . 0.489 5.597 0.706 6.6809 . . . . . . . . . . . . . . . 0.445 6.042 0.673 7.353

10 . . . . . . . . . . . . . . . 0.405 6.447 0.643 7.99611 . . . . . . . . . . . . . . . 0.368 6.815 0.614 8.61012 . . . . . . . . . . . . . . . 0.334 7.149 0.586 9.19613 . . . . . . . . . . . . . . . 0.304 7.453 0.559 9.75514 . . . . . . . . . . . . . . . 0.276 7.729 0.534 10.28815 . . . . . . . . . . . . . . . 0.251 7.980 0.509 10.79816 . . . . . . . . . . . . . . . 0.226 8.209 0.485 11.28417 . . . . . . . . . . . . . . . 0.208 8.416 0.464 11.74818 . . . . . . . . . . . . . . . 0.189 8.605 0.443 12.19119 . . . . . . . . . . . . . . . 0.172 8.777 0.423 12.61420 . . . . . . . . . . . . . . . 0.156 8.993 0.404 13.01821 . . . . . . . . . . . . . . . 0.142 9.074 0.385 13.40322 . . . . . . . . . . . . . . . 0.129 9.203 0.368 13.77123 . . . . . . . . . . . . . . . 0.117 9.320 0.351 14.12224 . . . . . . . . . . . . . . . 0.107 9.427 0.335 14.45825 . . . . . . . . . . . . . . . 0.097 9.524 0.320 14.777


C-3

Economic life Differential inflation rate—7%* Discount rate—10% Differential inflation rate—8%* Discount rate—10%years

Rate C Rate D

One-timecost factors One-time cost factorsRecurring benefits/cost Recurring benefits/costfactors factors

1 . . . . . . . . . . . . . . . 0.986 0.986 0.991 0.9912 . . . . . . . . . . . . . . . 0.959 1.946 0.973 1.9643 . . . . . . . . . . . . . . . 0.933 2.879 0.955 2.9194 . . . . . . . . . . . . . . . 0.908 3.787 0.938 3.8575 . . . . . . . . . . . . . . . 0.883 4.670 0.921 4.7776 . . . . . . . . . . . . . . . 0.859 5.529 0.904 5.6817 . . . . . . . . . . . . . . . 0.836 6.364 0.888 6.5698 . . . . . . . . . . . . . . . 0.813 7.177 0.871 7.4409 . . . . . . . . . . . . . . . 0.791 7.968 0.856 8.296

10 . . . . . . . . . . . . . . . 0.769 8.737 0.840 9.13611 . . . . . . . . . . . . . . . 0.748 9.485 0.825 9.96112 . . . . . . . . . . . . . . . 0.728 10.212 0.810 10.77013 . . . . . . . . . . . . . . . 0.708 10.920 0.795 11.56514 . . . . . . . . . . . . . . . 0.688 11.608 0.781 12.34615 . . . . . . . . . . . . . . . 0.670 12.278 0.766 13.11216 . . . . . . . . . . . . . . . 0.651 12.930 0.752 13.864 17 . . . . . . . . . . . . . . . 0.634 13.563 0.739 14.60318 . . . . . . . . . . . . . . . 0.616 14.180 0.725 15.32919 . . . . . . . . . . . . . . . 0.600 14.779 0.719 16.04120 . . . . . . . . . . . . . . . 0.583 15.363 0.699 16.74021 . . . . . . . . . . . . . . . 0.567 15.930 0.687 17.42722 . . . . . . . . . . . . . . . 0.552 16.482 0.674 18.10123 . . . . . . . . . . . . . . . 0.537 17.019 0.662 18.76224 . . . . . . . . . . . . . . . 0.522 17.541 0.650 19.41225 . . . . . . . . . . . . . . . 0.508 18.049 0.638 20.050

C.l.9 Applicability C.2.1.2 Annual Maintenance Costs. In spite ofThe policy and method outlined herein are appli-cable to all buildings with siding problems,including family housing.

C.1.10 Designation of Siding as RepairIf the existing siding has deteriorated or will not insulation will produce increases in fuel savingssuccessfully hold paint for the minimum period with diminishing savings until an optimum ispresented in the appropriate regulations, re-siding reached. Some sidings provide R values as an in-may be classified as repair when life cycle costing herent characteristic while others such as un-proves re-siding to be the most economical backed aluminum, steel, and vinyl providealternative. negligible values. The U factor of the complete

system must be considered in the analysis.C.2 Insulation Comparison

C.2.l Options ConsideredTwo options were considered: Option I — Sand-blasting and repainting; or Option II — Over-layment residing. Various types of siding coupledwith various types and thicknesses of insulationshould be considered to arrive at an optimumcombination. Factors to be considered are:C.2.1.1 Initial Construction Costs. Re-sidingcosts should include the finish and trim materialaround doors, windows, vents, utility service,and mechanical equipment. These trim costs willvary with the various thicknesses of insulationselected and the greater thicknesses may requireextensive reworking of jambs, sills, and heads.

manufacturers' claims, siding is not maintenancefree. An estimate must be made of the amountthat has to be replaced each year due to abuse andaccidental damage.C.2.1.3 Energy Savings. Increases in thickness of

C.2.1.4 Appearance Life Expectancy of Siding.After a number of years all brands of sidingexhibit some color shift. Eventually there will bea dam-aged panel replaced with new materialwhich will differ significantly in color from theexisting. When the color differences becomeunsightly, it will be necessary to paint the entirewall even though the original finish is sound.C.2.1.5 Life Expectancy of Substrate. Allsubstrates will eventually wear out. Excessivemoisture, corrosive atmosphere and sunshine willcause siding to rust, corrode or shatter requiringcomplete replacement.

C.2.2 Life Cycle Energy Cost ComparisonIncreased insulation reduces annual energy costs


C-4

and increases initial installation and annual main- example it is assumed the optimum U-factor istenance costs. Greater amounts of insulation may 0.10 Btu/hr-ft -F.produce unusual installation problems and in-crease the initial costs disproportionately to theenergy saving. The optimum amount of insulationcan only be determined by complete analysis of Having determined that adding insulation will becosts and savings. According to table 9-2, DoD cost effective for the building retention time,Construction Criteria Manual 4270.1M, buildings comparisons with continuing existing siding mayto be heated to 65E F (18.4E C) must have a U- be eliminated. The justification for one type offactor in walls of 0.1 Btu/hr-ft -F either in new siding over others will depend on current2

construction or in repair renovation work. While installed costs of siding; effective life expectancya U-factor of 0.1 may not represent the optimum of the siding substrate before completevalue it is the maximum requirement and will replacement is required; effective life expectancyserve as a basis for comparing energy costs with of the siding finish material before cyclicalthe existing wall. repainting in required; and retention time of

C.2.2.1 Example assumptions: of siding are selected, all obtaining the same U

Exterior Building wall Area . . . . . . . . . . . . . . = 4000 ft 2Fuel Oil Cost Escalation Factor . . . . . . . . . . . = 8 etElectricity Cost Escalation Factor . . . . . . . . . . = 7 etConstruction Cost Escalation Factor . . . . . . . . = 5 petDifferential Inflation Discount Rate . . . . . . . . . = 10 petRetention Time of Building . . . . . . . . . . . . . . = 5 yrsDesign Heating Temperature Difference . . . . . . = 48EF (8.9EC)Equivalent Cooling Temperature Difference . . . = 35EF (1.7EC)

C.2.2.2 Comparison Analysis:

Unit Cost PVItem cost source * factor Cost

OPTION I —ContinueExisting SystemRepaint . . . . . . . . . . 1365 C.14.4.1 1.0 $1,365Repaint . . . . . . . . . . 455 C.14.4.1 4.461 2,030Heat . . . . . . . . . . . . 1606 C.14.4.1 4.777 7,672Cool . . . . . . . . . . . . 288 C.14.4.1 4.670 1,345

Total Cost . . . . . . . . . . . . . . . . . . . . . . . . . . . . $12,412

OPTION II —Insulated to U=0.1 with sidingoverlayment

Reside . . . . . . . . . . . 5925 C.14.4.3 1.0 $5,925Repair . . . . . . . . . . . 38 C.14.4.3 4.461 167Heat . . . . . . . . . . . . 703 C.14.4.2 4.777 3,358Cool . . . . . . . . . . . . 126 C.14.4.2 4.670 588

Total Cost . . . . . . . . . . . . . . . . . . . . . . . . . . . . $10,038

*Paragraph number of cost data source.

C.2.2.3 Conclusions. Adding insulation to arelatively uninsulated building is cost effectiveand be-comes even more cost effective as fuelprices rise. The optimum thickness of insulationmay be determined by using realistic costs andretention time of building. It appears that addinginsulation with new siding overlayment would notbe cost effective for retention times of less than5 years. For the balance of this illustrative

2

C.3 Siding ComparisonC.3.1 Life Cycle Siding Costs

building. In the example that follows four types

factor by adding appropriate amounts ofinsulation. Building retention time is not deter-mined in order to illustrate the impact retentiontime has on final decision.

C.3.2 Example assumptionsBuilding will be the same as in C.2 exceptbuilding retention time is unspecified and sidingcharacteristics are as follows:C.3.2.1 Siding Material "A"—A heavy dutysiding with a factory-bonded high-qualify filmfinish material. The siding requires ¾ inch ofrigid polystyrene insulation board to obtain therequired U-factor. The finish material isestimated to require 4-year cyclical paintingstarting in the 21st year, with completereplacement of the substrate in the 31st year.C.3.2.2 Siding Material "B"—A light-duty sidingwith a factory-applied paint finish. The siding re-quires ¾ inch of rigid polystyrene insulationboard to obtain the required U4actor. The finishmaterial is estimated to require 4-year cyclicalpainting staring in the 13th year, with completereplacement of the substrate in the 25th year.C.3.2.3 Siding Material "C"—A heavy-dutysiding with a factory applied enamel paint finish.The siding requires ¾ inch of rigid polystyreneinsulation board to obtain the required U-Factor.The finish material is estimated to require 4-yearcyclical painting, starting in the 13th year withcompete replacement of the substrate in the 31styear.C.3.2.4 Siding Material "D"— wood fiberboardhaving a factory-appied paint finish. The sidinghas inherent insulative value requiring ¼ inch ofadditional rigid polystyrene board insulation toachieve the required U/factor. The finish materialis estimated to require 3-year cyclical painting,starting in the 9th year, with complete replace-ment of substrate in the 15th year.

Uav 'S

100(Us) % 1 &

S100

(Ui) EQ. 9

Uav '20100

(0.13) % 1 &20100

(0.233)


C-5

C.3.3 Comparison Analysis the analysis. Present value costs, in the year oc-Since U-factors are equal for all cases, the fuelcosts will be equal and may be eliminated from

curring, are tabulated in table C-3.

TABLE C-3. -Present Value Costs of Sidings

Year Yr

Siding material“A” “B” “C” “D”

P.V. of Accum. P.V. of Accum. P.V. of Accum. P.V. of Accum.M&R total M&R total M&R total M&R totalcosts* costs costs* costs costs* costs costs* costs

0 . . . . . . . . . . . . . . 6725 6725 5925 5925 6125 6125 4825 4825 05 . . . . . . . . . . . . . . 126 6851 122 6047 324 6449 20 5028 59 . . . . . . . . . . . . . . 104 6955 101 6148 269 6718 594 5622 912 . . . . . . . . . . . . . — 6955 — 6148 — 6718 752 6374 1213 . . . . . . . . . . . . . 87 7042 442 6590 581 7299 — 6374 1315 . . . . . . . . . . . . . — 7042 — 6590 — 7299 2456 8830 1517 . . . . . . . . . . . . . 72 7114 552 7142 668 7967 — 8830 1720 . . . . . . . . . . . . . — 7114 — 7142 — 7967 101 8931 2021 . . . . . . . . . . . . . 306 7420 458 7600 554 8521 — 8931 2124 . . . . . . . . . . . . . — 7420 — 7600 — 8521 296 9297 2425 . . . . . . . . . . . . . 382 7802 1896 9496 461 8982 — 9227 25

*Present Value of Maintenance and Repair costs is obtained by multiplying current cost data presented in paragraph C.14.4 by the RecurringBenefits/Costs factors for the year the cost will be incurred as shown in table C-2.

C.3.4. ConclusionThe foregoing tabulation of costs indicates thatfor retention periods of less than 11 years, sidingoverlayment material "D" should be used. For 12to 16 years-siding overlayment material"B"should be used, and for periods of 17 years orgreater, siding overlayment material "A" shouldbe selected.

C.4 Cost Data

C.4.l Wall U-values Option I-Existing:

Wall componentR-value

Through ThroughWall Framing

Outside Air Film (15-mph wind) . . . . . . 0.17 0.173/4-inch shiplap siding . . . . . . . . . . . . 1.05 1.053/4-inch solid wood sheathing . . . . . . . 0.94 0.943-1/2-inch airspace . . . . . . . . . . . . . . . 1.01 — Nominal 2" x 4" wood stud . . . . . . . . . — 4.381/2-inch gypssum wall board . . . . . . . . 0.45 0.45Inside air film . . . . . . . . . . . . . . . . . . 0.68 0.68 R= . . . . . . . . . . . . . . . . 4.30 7.67 TOTAL U = 1/R . . . . . . . . . . . . . . 0.233 0.13

Using:

(1977 ASHRAE Fundamentals Handbook, pg. 22.5)

Where:

U = Average U-value for building sectionav

U = U-value for area between framing membersi

U = U-value for area backed by framing memberss

S = Percentage of area backed by framing mem-bers

Assume 20 percent framing.

=0.21 Btu/hr-ft -F2

Uav 'S

100(Us) % 1 &

S100

(Ui) '

Uav '20100

(0.073) % 1 &20100

(0.097) '

'0.092 Btu/hr&ft 2&F

E 'HL × D × 24

t × VCD CF


C-6

Option II—Overlayment re-siding with insulation:

Wall component

R-value

Through ThroughWall Framing

Existing . . . . . . . . . . . . . . . . . . . . . . 4.30 7.67

New siding with d inch insulating board/foil-backed . . . . . . . . . . . . . . . 1.82 1.823/4-inch rigid polysterene . . . . . . . . . . 4.16 4.16 R= . . . . . . . . . . . . . . . . 10.28 13.65 TOTAL U = 1/R . . . . . . . . . . . . . . 0.097 0.073

The differences in R-value between the mostcommon types of siding — steel, aluminum, andsolid vinyl are negligible. However, some sidingsare themselves significantly insulative or are man-ufactured with an integral insulation backer layerand the U-values of these types should becalculated independently. Various thicknesses ofinsulation impact on fuel savings. A separatepreliminary analysis should be made of differingthicknesses of insulation to determine thethickness and corresponding U-value for optimumsavings over the life of the building. Includedshould be the variable costs of finishing arounddoors, windows, etc., and special means ofsupport and attachment for the greater thicknessesof insulation. In this example the optimumthickness of insulation is assumed to be 3/4 inchof rigid polystyrene which produces a U-valuelower than the maximum of 0.10 required byDOD regulations in new or rehabilitative work.

C.4.2 Heating and Cooling LoadsC.4.2. 1 Use the equation Q = U A(t - t ) toav i odetermine the heat gain and loss in Btu per hour.U is the coefficent determined in C.4.1. above,avA is the wall area, and(t - t ) is the differencei o

between the design interior and design exteriortemperature in E Fahrenheit.

Heating:

Existing Q=(0.21)(4,000)(65-17)=40,820 Btu/hrWith Overlayment Q =(0.092)(4,000)(65-17)=17,664 Btu/hr

C.4.2.2 Use the equation Q=U A(CLTD).avAssume frame wall, each exposure having equalarea, i.e., 1,000 ft on north, east, south, and west2

walls. The average Cooling Load TemperatureDifference (CLTD)=35EF @ 1,400 hr, ASHRAEFundamentals Handbook, Table 7,1977, p.25.9.(Calculations are made on transmitted sensible heatgain only. Other heat gains are not affected bysiding modifications.)

Cooling:Existing Q=(0.21)(4,000)(35) = 29,400

Btu/hrWith OverlaymentQ=(0.092)(4,000)(35)=12,880 Btu/hr

C.4.3 Energy Consumption EstimatesHeating: Using eq. 1 on p. 43.8 of the 1976

ASHRAE Systems Handbook for calculating energyconsumption by the Modified Degree Day Method:

E = Fuel consumption for the estimate periodHL= Design heat loss, Btu/hrD=Degree days; assume 3865 F —Dayt = Temperature difference = (65 — 17) = Rated efficiency; assume 70 pctV=Heating value of fuel; 138,700 Btu/gal for

distillate fuel oilC = Correction factor for heating effect vsD

degree daysC = Part load correction factorFTable 3*, assume 40 percent oversizing, CF=

1.79Table 2*, 17EF design temperature C approx.D

=0.86*1976 ASHRAE Systems Handbook, p.43.8

C.4.3.1 Existing Siding, H =40,320 Btu/hrL

E' 40,320 Btu/hr × 3865 F & Day × 24 hr/day48 F × 0.70 × 138,700 Btu/gal

E' 17,664 × 3865 × 2448 F × 0.70 × 138,700

(0.86)(1.79)

E' 29,400 Btu/hr × 1.63 kW/ton × 1,200 hr12,000 Btu/hr/ton

E' 12,880 Btu/hr × 1.63 kW/ton × 1,200 hr12,000 Btu/hr/tonl


C-7

(0.86)(1.79)

E=1,235 galCost=1,235 gal x $1.30/galCost $1,606/year

C.4.3.2 Siding Overlayment, H =17,664 Btu/hrL

E=541 galCost=541 gal x $1.30/galCost $703

C.4.3.3 Cooling: Use Equivalent Full LoadHour Method. Assume 1200 full load hours ofoperation of equipment. Using Table 4 on p.43.9in the 1976 ASHRAE Systems Handbook, andassuming central air conditioning unit; powerinput is approximately 1.63 kW/ton.

a. Existing Siding:

=4,792 kWh

Cost=4,792 kWh x $0.06/kWh=$288/yr

b. Siding Overlayment:

=2,099 kWh

Cost=2,099 kWh x $0.06/kWh=$126/yr

C.4.4 Construction Costs:

a. Existing Siding

Paint wood siding (primer + 1 coat)0.26/

SF × 4,000 SF . . . . . . . . . . . . . . . . . . . . . = $1,040

Paint wood trim (primer + 1 coat)0.44/

SF × 200 SF . . . . . . . . . . . . . . . . . . . . . . = 88

Windows and doors (primer + 1 coat)0.25/

SF × 500 SF . . . . . . . . . . . . . . . . . . . . . . = 125

Repair of Siding 2.80/SF x 40 SF . . . . . . . . . . . = 112

Total — Initial and M&R costs

each 3 years . . . . . . . . . . . . . . . . . . . . $1,365

Average annual cost ÷$1,365-

3 . . . . . . . . . . . . . . . . . . . . . = 455

b. Sliding Overlayment—Material "A "—Lifeexpectancy of substrate is 30 years and finish is 20years. Repainting will start in 21st year with com-plete replacement of siding in 31st year.

Install new siding overlayment 1.15/

SF × 4,000 SF . . . . . . . . . . . . . . . . . . . = $4,600

Bead-board backer 0.10/SF × 4,000 SF . . . . . . . = 400

3/4" polystyrene foam insulation 0.40/

SF × 4,000 SF . . . . . . . . . . . . . . . . . . . = 1,600

Paint windows and doors (as above) 0.25

SF × 500 SF . . . . . . . . . . . . . . . . . . . . = 125

Total — Initial Cost and Replace-

ment Cost in 31st Year . . . . . . . . . . . . . $6,725

Replace damaged siding 3.00/SF × 10 SF . . . . . = $30

Paint windows and doors (as above) 0.25/

SF × 500SF . . . . . . . . . . . . . . . . . . . . . = 125

Total — M&R Costs (5th yr and

each 4 yrs thereafter) . . . . . . . . . = $155

Paint without priming (1 coat) 0.16/

SF × 4,0005F . . . . . . . . . . . . . . . . . . . = 640

Total — M&R Cost in 21st year . . . . . . . . $795

Repaint Siding: Add prime coat 0.10/

SF × 4,000SF . . . . . . . . . . . . . . . . . . . = 400

Total — M&R Cost after 21st

year . . . . . . . . . . . . . . . . . . = $1,195


C-8

c. Siding Overlayment—Material "B"—Life Paint windows and doors (as above) . . . . . . . . . = 125

expectancy of substrate is 24 years and finish is Total—Initial Cost and Replace

12 years. Repainting will start in 13th year with ment Cost in 3lth year . . . . . . . . = $6,125

complete replacement of siding in 25th year. Replace damaged siding 2.75/SFx 100 SF . . . . . = $275

Install new siding overlayment 0.95/ each 4 yrs thereafter) . . . . . . . . = $400

SF × 4,000 SF . . . . . . . . . . . . . . . . . . . = $3,800

Bead-board backer (as above) . . . . . . . . . . . . . . = 400

3/4-inch polystyrene foam insulation (as Repaint Siding: Add prime coat (as above) . . . . . = 400

above . . . . . . . . . . . . . . . . . . . . . . . . . . = 1,600

Paint windows and doors (as above) . . . . . . . . . = 125

Total — Initial Cost and Replace-

ment Cost in 25st Year . . . . . . . . . . . . . $5,925

Replace damaged siding 2.50/SF × 10 SF . . . . . = $25


Total — M&R Costs (5th yr and years. Repainting will start in 9th year with com-each 4 yrs thereafter) . . . . . . . . . = $150

Average annual M&R cost 150: 4 . . . . . . . . . . . = 38×

Paint without priming (as abive . . . . . . . . . . . . . = 640

Total — M&R Cost in 13th year . . . . . . . . $790

Repaint Siding: Add prime coat (as above) . . . . . = 400

Total — M&R Cost after 13th d inch rigid polystyrene insulation 0.25/

year . . . . . . . . . . . . . . . . . . = $1,190

d. Siding Overlayment-Material "C"—Life ex- Total--Initial Cost and Replace-

pectancy of substrate is 30 years and finish is 12 ment Cost in 15th year . . . . . . . = $4,825

years. Repainting will start in 13th year with Replace damaged siding 2.50/SF×50 SF . . . . . . = $125

complete replacement in 31st year. Although the Paint windows and doors (as above) . . . . . . . . . = 125

life expectancy of this siding substrate is quite Total—M&R Costs (5th yr and

long it is highly susceptible to damage therefore 20th yr) . . . . . . . . . . . . . . . . . = $250

annual maintenance costs are high. Paint without priming (as above) . . . . . . . . . . . . = 640

Install new siding overlayment $1.00/ 24th yr . . . . . . . . . . . . . . . . . . = $890

Sfx4,000 SF . . . . . . . . . . . . . . . . . . . . . = $4,000

Bead-board backer (as above) . . . . . . . . . . . . . . = 400

3/4-inch polystyrene foam insulation (as

above) . . . . . . . . . . . . . . . . . . . . . . . . . = 1,600


Total—M&R Costs (5th yr and

Paint without priming (as above) . . . . . . . . . . . . = 640

Total—M&R Cost in 13th year . . . . = $1,040

Total—M&R Cost after 13th

year . . . . . . . . . . . . . . . . . . . . = $1,440

e. Siding Overlayment-Material "D"—Life ex-pectancy of substrate is 14 years and finish is 8

plete replacement of siding in 15th year.

Install new siding overlayment 0.95/

SF×4,000 SF . . . . . . . . . . . . . . . . . . . . = $3,800

SF×4,000 SF . . . . . . . . . . . . . . . . . . . . = 1,000


Total—M&R Cost in 9th and

Repaint Siding: Add prime coat (as above) . . . . . = 400

Total—M&R Cost in 12th year . . . . = $1,290

PIN: 005243-000

Documents

Tm5_620_Facilities Engineering Maintenance and Repair of Architectural and Structural Elements of Buildings and Structures