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The Secretary of the Interiors Standardsfor the Treatment of Historic Properties

with Guidelines forPreserving, Rehabilitating

Restoring&ReconstructingHistoric Buildings


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The Secretary of the Interior is responsible for establishing professional standards and providing advice on thepreservation and protection of all cultural resources listed in or eligible for listing in the National Register ofHistoric Places. The Secretary of the Interiors Standards for the Treatment of Historic Properties, apply toall proposed development grant-in-aid projects assisted through the National Historic Preservation Fund, andare intended to be applied to a wide variety of resource types, including buildings, sites, structures, objects, anddistricts. They address four treatments: Preservation, Rehabilitation, Restoration, and Reconstruction. Thetreatment Standards, developed in 1992, were codified as 36 CFR Part 68 in the July 12, 1995 Federal Register(Vol. 60, No. 133). They replace the 1978 and 1983 versions of 36 CFR 68 entitled, The Secretary of theInteriors Standards for Historic Preservation Projects. The Guidelines in this book also replace the Guidelinesthat were published in 1979 to accompany the earlier Standards.

Please note that The Secretary of the Interiors Standards for the Treatment of Historic Properties are only

regulatory for projects receiving federal grant-in-aid funds; otherwise, the Standards and Guidelines are intend-ed only as general guidance for work on any historic building.

Finally, another regulation, 36 CFR Part 67, focuses on certified historic structures as defined by the IRS Code of1986. The Standards for Rehabilitation cited in 36 CFR 67 should always be used when property owners are seek-ing certification for Federal tax benefits.

Library of Congress Cataloging-in-Publication Data

Weeks, Kay D.The Secretary of the Interiors standards for the treatment of historic properties: with

guidelines for preserving, rehabilitating, restoring & reconstructing historic buildings /Kay D. Weeks and Anne E. Grimmer.

p. cm.ISBN 0-16-048061-21. Architecture--United States--Conservation and restoration--Standards. 2. Historic

buildings--United States--Conservation and restoration--Standards. I. Grimmer, Anne E.II. United States, National Park Service. Preservation Assistance Division. III. Title.

NA106.W44 1995 95-23913720".28"8021873--dc20 CIP

Rev.


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The Secretary of the Interiors Standardsfor the Treatment of Historic Properties

with Guidelines forPreserving, Rehabilitating,Restoring&ReconstructingHistoric BuildingsKay D. Weeks and Anne E. Grimmer

U.S. Department of the InteriorNational Park ServiceCultural Resource Stewardship and PartnershipsHeritage Preservation Services

Washington, D.C.1995


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Photo CreditsFront and Back Covers

Bangor House, Bangor, Maine, circa 1880. Historic photo (front) and drawing (back): Courtesy, Maine StateHistoric Preservation Office.

Historical Overview (Materials and Features)

Building Exterior: Masonry.Jack E. Boucher, HABS.

Building Exterior: Wood.Jack E. Boucher, HABS.

Building Exterior: Architectural Metals. Cervin Robinson, HABS.

Building Exterior: Roofs.Jack E. Boucher, HABS.

Building Exterior: Windows.Jack E. Boucher, HABS.

Building Exterior: Entrances and Porches.Jack E. Boucher, HABS.

Building Exterior: Storefronts.Jack E. Boucher, HABS.

Building Interior: Structural Systems. Cervin Robinson, HABS.

Building Interior: Spaces, Features and Finishes. Brooks Photographers, HABS Collection.

Building Interior: Mechanical Systems. National Park Service Files.

Building Site.Jack E. Boucher, HABS.

Setting (District/Neighborhood). Charles Ashton.

Energy Conservation. Laura A. Muckenfuss.

New Additions to Historic Buildings. Rodney Gary.Accessibility Considerations. Department of Cultural Resources, Raleigh, North Carolina.

Health and Safety Considerations. National Park Service Files.

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Chapter Heads

PreservationHale House, Los Angeles, California. Photos: Before: National Park Service files; After: Bruce Boehner.

RehabilitationStorefront, Painted Post, New York, after rehabilitation. Photo: Kellogg Studio.

RestorationCamron-Stanford House, Oakland, California. Photos: Before: National Park Service files; After: Courtesy, JamesB. Spaulding.

ReconstructionGeorge Washington Memorial House at Washington Birthplace National Monument, Westmoreland County, Virginia.Photo: Richard Frear.

Text

It should be noted that those photographs used to illustrate the guidelines text that are not individually creditedin the captions are from National Park Service files.

Acknowledgements

The Standards for the Treatment of Historic Properties, published in 1992, were reviewed by a broad cross-sectionof government entities and private sector organizations. The Guidelines for Preserving, Rehabilitating, Restoringand Reconstructing Historic Buildingswere developed in cooperation with the National Conference of StateHistoric Preservation Officers and reviewed by individual State Historic Preservation Offices nationwide. We

wish to thank Stan Graves and Claire Adams, in particular, for their thoughtful evaluation of the new material.Dahlia Hernandez provided administrative support throughout the project.

Finally, this book is dedicated to H. Ward Jandl, whose long-term commitment to historic preservation helpeddefine the profession as we know it today.

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Historic Resource Types & Examples

Building: houses, barns, stables, sheds, garages, court-houses, city halls, social halls, commercial buildings,libraries, factories, mills, train depots, hotels, theaters, sta-tionary mobile homes, schools, stores, and churches.

Site: habitation sites, funerary sites, rock shelters, villagesites, hunting and fishing sites, ceremonial sites, petro-glyphs, rock carvings, ruins, gardens, grounds, battlefields,campsites, sites of treaty signings, trails, areas of land,shipwrecks, cemeteries, designed landscapes, and naturalfeatures, such as springs and rock formations, and landareas having cultural significance.

Structure: bridges, tunnels, gold dredges, firetowers,canals, turbines, dams, power plants, corn-cribs, silos,roadways, shot towers, windmills, grain elevators, kilns,mounds, cairns, palisade fortifications, earthworks, rail-

road grades, systems of roadways and paths, boats andships, railroad locomotives and cars, telescopes, carousels,bandstands, gazebos, and aircraft.

Object: sculpture, monuments, boundary markers, statu-ary, and fountains.

District: college campuses, central business districts, resi-dential areas, commercial areas, large forts, industrial com-

plexes, civic centers, rural villages, canal systems, collec-tions of habitation and limited activity sites, irrigation sys-tems, large farms, ranches, estates, or plantations, trans-portation networks, and large landscaped parks.

(Sidebar adapted from National Register Property and ResourceTypes, p. 15, National Register Bulletin 16A, How to Complete theNational Register Form, published by the National Register Branch,Interagency Resources Division, National Park Service, U.S.

Department of the Interior, 1991.)

The Secretary of the Interiors Standards for the Treatment of Historic Properties may be applied to one historicresource type or a variety of historic resource types; for example, a project may include a complex of buildings such as ahouse, garage, and barn; the site, with a designed landscape, natural features, and archeological components; structuressuch as a system of roadways and paths or a bridge; and objects such as fountains and statuary.

Zoar Historic District, Ohio. Aerial view. Photo: National Park Service.

Elmendorf, Lexington, Kentucky. Photo: Charles A. Birnbaum.


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Historical OverviewBuilding Exterior Materials

Masonry

Stoneis one of the more lasting of masonry buildingmaterials and has been used throughout the history ofAmerican building construction. The kinds of stonemost commonly encountered on historic buildings inthe U.S. include various types of sandstone, lime-stone, marble, granite, slate and fieldstone. Brickvar-ied considerably in size and quality. Before 1870,

brick clays were pressed into molds and were oftenunevenly fired. The quality of brick depended on thetype of clay available and the brick-making tech-niques; by the 1870swith the perfection of anextrusion processbricks became more uniform anddurable. Terra cotta is also a kiln-dried clay productpopular from the late 19th century until the 1930s.The development of the steel-frame office buildings

in the early 20th century contributed to the wide-spread use of architectural terra cotta. Adobe, whichconsists of sun-dried earthen bricks, was one of theearliest building materials used in the U.S., primarilyin the Southwest where it is still popular.

Mortaris used to bond together masonry units.Historic mortar was generally quite soft, consistingprimarily of lime and sand with other additives. By

the latter part of the 19th century, portland cementwas usually added resulting in a more rigid and non-absorbing mortar. Like historic mortar, earlystuccocoatings were also heavily lime-based, increasing inhardness with the addition of portland cement in thelate 19th century. Concretehas a long history, beingvariously made of tabby, volcanic ash and, later, ofnatural hydraulic cements, before the introduction of

portland cement in the 1870s. Since then, concretehas also been used in its precast form.

While masonry is among the most durable of historicbuilding materials, it is also very susceptible to dam-age by improper maintenance or repair techniquesand harsh or abrasive cleaning methods.

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Wood

Wood has played a central role in American buildingduring every period and in every style. Whether as

structural members, exterior cladding, roofing, interi-or finishes, or decorative features, wood is frequentlyan essential component of historic buildings.

Because it can be easily shaped by sawing, sanding,planing, carving, and gouging, wood is used forarchitectural features such as clapboard, cornices,brackets, entablatures, shutters, columns andbalustrades. These wooden features, both functionaland decorative, are often important in defining thehistoric character of the building.

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Architectural Metals

Architectural metal featuressuch as cast ironfacades, porches, and steps; sheet metal cornices, sid-

ing, roofs, roof cresting and storefronts; and cast orrolled metal doors, window sash, entablatures, andhardwareare often highly decorative and may beimportant in defining the overall character of historicAmerican buildings.

Metals commonly used in historic buildings includelead, tin, zinc, copper, bronze, brass, iron, steel, andto a lesser extent, nickel alloys, stainless steel and alu-minum. Historic metal building components wereoften created by highly skilled, local artisans, and bythe late 19th century, many of these componentswere prefabricated and readily available from catalogsin standardized sizes and designs.

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Building Exterior Features

Roofs

The roofwith its shape; features such as cresting,dormers, cupolas, and chimneys; and the size, color,and patterning of the roofing materialis an impor-tant design element of many historic buildings. Inaddition, a weathertight roof is essential to thelongterm preservation of the entire structure.Historic roofing reflects availability of materials, levelsof construction technology, weather, and cost.

Throughout the country in all periods of history,wood shingleshave been usedtheir size, shape, anddetailing differing according to regional craft prac-tices.

European settlers used clay tilefor roofing at least asearly as the mid-17th century. In some cities, such asNew York and Boston, clay tiles were popularly usedas a precaution against fire. The Spanish influence in

the use of clay tiles is found in the southern, south-western and western states. In the mid-19th century,tile roofs were often replaced bysheet-metal, which islighter and easier to maintain.

Evidence of the use ofslatefor roofing dates from themid-17th century. Slate has remained popular for itsdurability, fireproof qualities, and its decorative appli-

cations. The use of metals for roofing and roof fea-tures dates from the 18th century, and includes theuse ofsheet metal, corrugated metal, galvanized metal,tin-plate, copper, leadand zinc.

New roofing materials developed in the early 20thcentury include built-up roll roofing, and concrete,asbestos, and asphalt shingles.

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Windows

Technology and prevailing architectural styles haveshaped the history of windows in the United States

starting in the 17th century with wooden casementwindows with tiny glass panes seated in lead cames.From the transitional single-hung sash in the early1700s to the true double-hung sash later in the cen-tury, these early wooden windows were characterizedby small panes, wide muntins, and decorative trim.As the sash thickness increased, muntins took on athinner appearance as they narrowed in width butincreased in thickness.

Changes in technology led to larger panes of glass sothat by the mid-19th century, two-over-two lightswere common; the manufacture of plate glass in theUnited States allowed for use of large sheets of glass incommercial and office buildings by the late 19th cen-tury. With mass-produced windows, mail order dis-tribution, and changing architectural styles, it was

possible to obtain a wide range of window designsand light patterns in sash. Early 20th century designsfrequently utilized smaller lights in the upper sashand also casement windows. The desire for fireproofbuilding construction in dense urban areas con-tributed to the growth of a thriving steel windowindustry along with a market for hollow metal andmetal clad wooden windows.

As one of the few parts of a building serving as bothan interior and exterior feature, windows are nearlyalways an important part of a historic building.

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Entrances and Porches

Entrances and porches are quite often the focus ofhistoric buildings, particularly on primary elevations.

Together with their functional and decorative featuressuch as doors, steps, balustrades, pilasters, and entab-latures, they can be extremely important in definingthe overall character of a building. In many cases,porches were energy-saving devices, shading southernand western elevations. Usually entrances and porch-es were integral components of a historic buildingsdesign; for example, porches on Greek Revival hous-es, with Doric or Ionic columns and pediments,echoed the architectural elements and features of thelarger building. Central one-bay porches or arcadedporches are evident in Italianate style buildings of the1860s. Doors of Renaissance Revival style buildingsfrequently supported entablatures or pediments.Porches were particularly prominent features ofEastlake and Stick Style houses in which porch posts,railings, and balusters were characterized by a massive

and robust quality, with members turned on a lathe.Porches of bungalows of the early 20th century werecharacterized by tapered porch posts, exposed postand beams, and low pitched roofs with wide over-hangs. Art Deco commercial buildings were enteredthrough stylized glass and stainless steel doors.

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Storefronts

The earliest extant storefronts in the U.S., datingfrom the late 18th and early 19th centuries, had bay

or oriel windows and provided limited display space.The 19th century witnessed the progressive enlarge-ment of display windows as plate glass became avail-able in increasingly larger units. The use of cast ironcolumns and lintels at ground floor level permittedstructural members to be reduced in size. Recessedentrances provided shelter for sidewalk patrons andfurther enlarged display areas. In the 1920s and1930s, aluminum, colored structural glass, stainlesssteel, glass block, neon, and other new materials wereintroduced to create Art Deco storefronts.

The storefront is usually the most prominent featureof a historic commercial building, playing a crucialrole in a stores advertising and merchandising strate-gy. Although a storefront normally does not extendbeyond the first story, the rest of the building is often

related to it visually through a unity of form anddetail. Window patterns on the upper floors, corniceelements, and other decorative features should becarefully retained, in addition to the storefront itself.

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Building Interior

Structural Systems

The types of structural systems found in the UnitedStates include, but are not limited to the following:wooden frame construction (17th c.), balloon frameconstruction (19th c.), load-bearing masonry con-struction (18th c.), brick cavity wall construction(19th c.), heavy timber post and beam industrial con-struction (19th c.), fireproof iron construction (19thc.), heavy masonry and steel construction (19th c.),skeletal steel construction (19th c.), and concrete slaband post construction (20th c.).

If features of the structural system are exposed such asloadbearing brick walls, cast iron columns, roof truss-es, posts and beams, vigas, or stone foundation walls,they may be important in defining the buildingsoverall historic character. Unexposed structural fea-tures that are not character-defining or an entire

structural system may nonetheless be significant inthe history of building technology. The structuralsystem should always be examined and evaluatedearly in the project planning stage to determine itsphysical condition, its ability to support any proposedchanges in use, and its importance to the buildingshistoric character or historical significance.

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Spaces, Features, and Finishes

An interior floor plan, the arrangement and sequence ofspaces, and built-in features and applied finishes are individu-

ally and collectively important in defining the historic charac-ter of the building. Interiors are comprised of a series of pri-mary and secondary spaces. This is applicable to all build-ings, from courthouses to cathedrals, to cottages and officebuildings. Primary spaces, including entrance halls, parlors,or living rooms, assembly rooms and lobbies, are defined notonly by their function, but also by their features, finishes, sizeand proportion.

Secondary spaces are often more functional than decorative,and may include kitchens, bathrooms, mail rooms, utilityspaces, secondary hallways, firestairs and office cubicles in acommercial or office space. Extensive changes can often bemade in these less important areas without having a detri-mental effect on the overall historic character.


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Mechanical Systems

Mechanical, lighting and plumbing systems improvedsignificantly with the coming of the Industrial

Revolution. The 19th century interest in hygiene,personal comfort, and the reduction of the spread ofdisease were met with the development of centralheating, piped water, piped gas, and network ofunderground cast iron sewers. Vitreous tiles inkitchens, baths and hospitals could be cleaned easilyand regularly. The mass production of cast iron radi-ators made central heating affordable to many; someradiators were elaborate and included special warm-ing chambers for plates or linens. Ornamental grillesand registers provided decorative covers for functionalheaters in public spaces. By the turn of the 20th cen-tury, it was common to have all these modern ameni-ties as an integral part of the building.

The greatest impacts of the 20th century on mechan-ical systems were the use of electricity for interior

lighting, forced air ventilation, elevators for tall build-ings, exterior lighting and electric heat. The new ageof technology brought an increasingly high level ofdesign and decorative art to many of the functionalelements of mechanical, electrical and plumbing sys-tems.

The visible decorative features of historic mechanicalsystems such as grilles, lighting fixtures, and orna-mental switchplates may contribute to the overall his-toric character of the building. Their identificationneeds to take place, together with an evaluation oftheir physical condition, early in project planning.On the other hand, mechanical systems need to workefficiently so many older systems, such as compressorsand their ductwork, and wiring and pipes often needto be upgraded or entirely replaced in order to meet

modern requirements.

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Building Site

The building site consists of a historic building orbuildings, structures, and associated landscape fea-

tures within a designed or legally defined parcel ofland. A site may be significant in its own right, orbecause of its association with the historic building orbuildings. The relationship between buildings andlandscape features on a site should be an integral partof planning for every work project.

Setting (District/Neighborhood)

The setting is the larger area or environment inwhich a historic property is located. It may be anurban, suburban, or rural neighborhood or a naturallandscape in which buildings have been constructed.The relationship of buildings to each other, setbacks,fence patterns, views, driveways and walkways, andstreet trees together create the character of a districtor neighborhood.

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Special Requirements

Work that must be done to meet accessibility require-ments, health and safety requirements or retrofitting to

improve energy efficiency is usually not part of the over-all process of protecting historic buildings; rather, thiswork is assessed for its potential impact on the historicbuilding.

Energy Efficiency

Some features of a historic building or site such as

cupolas, shutters, transoms, skylights, sun rooms,porches, and plantings can play an energy-conservingrole. Therefore, prior to retrofitting historic build-ings to make them more energy efficient, the firststep should always be to identify and evaluate existinghistoric features to assess their inherent energy-con-serving potential. If it is determined that retrofittingmeasures are appropriate, then such work needs to becarried out with particular care to ensure that thebuildings historic character is retained.

Accessibility Considerations

It is often necessary to make modifications to a his-toric building so that it will be in compliance withcurrent accessibility code requirements. Accessibilityto certain historic structures is required by three spe-

cific federal laws: the Architectural Barriers Act of1968, Section 504 of the Rehabilitation Act of 1973,and the Americans with Disabilities Act of 1990.Federal rules, regulations, and standards have beendeveloped which provide guidance on how to accom-plish access to historic areas for people with disabili-ties. Work must be carefully planned and undertak-en so that it does not result in the loss of character-

defining spaces, features, and finishes. The goal is toprovide the highest level of access with the lowestlevel of impact.

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Health and Safety Considerations

In undertaking work on historic buildings, it is neces-sary to consider the impact that meeting current

health and safety codes (public health, occupationalhealth, life safety, fire safety, electrical, seismic, struc-tural, and building codes) will have on character-defining spaces, features, and finishes. Special coor-dination with the responsible code officials at thestate, county, or municipal level may be required.Securing required building permits and occupancylicenses is best accomplished early in work project

planning. It is often necessary to look beyond theletter of code requirements to their underlying pur-pose; most modern codes allow for alterativeapproaches and reasonable variance to achieve com-pliance.

Some historic building materials (insulation, leadpaint, etc.) contain toxic substances that are poten-tially hazardous to building occupants. Following

careful investigation and analysis, some form ofabatement may be required. All workers involved inthe encapsulation, repair, or removal of known toxicmaterials should be adequately trained and shouldwear proper personal protective gear. Finally, preven-tive and routine maintenance for historic structuresknown to contain such materials should also bedeveloped to include proper warnings and precau-

tions.

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Standards forPreservation

&Guidelines for

PreservingHistoric Buildings

Preservation is defined as the act or process of applying mea-

sures necessary to sustain the existing form, integrity, andmaterials of an historic property. Work, including prelimi-nary measures to protect and stabilize the property, generally

focuses upon the ongoing maintenance and repair of historicmaterials and features rather than extensive replacement andnew construction. New exterior additions are not within thescope of this treatment; however, the limited and sensitiveupgrading of mechanical, electrical, and plumbing systemsand other code-required work to make properties functional is

appropriate within a preservation project.


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Standards for Preservation

1. A property will be used as it was historically, or be given a new use that maximizes the retention of dis-tinctive materials, features, spaces, and spatial relationships. Where a treatment and use have not been

identified, a property will be protected and, if necessary, stabilized until additional work may be under-taken.

2. The historic character of a property will be retained and preserved. The replacement of intact orrepairable historic materials or alteration of features, spaces, and spatial relationships that characterize aproperty will be avoided.

3. Each property will be recognized as a physical record of its time, place, and use. Work needed to stabi-lize, consolidate, and conserve existing historic materials and features will be physically and visually com-

patible, identifiable upon close inspection, and properly documented for future research.

4. Changes to a property that have acquired historic significance in their own right will be retained andpreserved.

5. Distinctive materials, features, finishes, and construction techniques or examples of craftsmanship thatcharacterize a property will be preserved.

6. The existing condition of historic features will be evaluated to determine the appropriate level of inter-

vention needed. Where the severity of deterioration requires repair or limited replacement of a distinctivefeature, the new material will match the old in composition, design, color, and texture.

7. Chemical or physical treatments, if appropriate, will be undertaken using the gentlest means possible.Treatments that cause damage to historic materials will not be used.

8. Archeological resources will be protected and preserved in place. If such resources must be disturbed,mitigation measures will be undertaken.


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conservingis recommended. Preservation strives toretain existing materials and features while employingas little new material as possible. Consequently, guid-ance for repairing a historic material, such as masonry,

again begins with the least degree of intervention pos-sible such as strengthening fragile materials throughconsolidation, when appropriate, and repointing withmortar of an appropriate strength. Repairing masonryas well as wood and architectural metal features mayalso include patching, splicing, or otherwise reinforc-ing them using recognized preservation methods.Similarly, within the treatment Preservation, portions

of a historic structural system could be reinforcedusing contemporary materials such as steel rods. Allwork should be physically and visually compatible,identifiable upon close inspection and documented forfuture research.

Limited Replacement In Kind of ExtensivelyDeteriorated Portions of Historic Features

If repair by stabilization, consolidation, and conserva-tion proves inadequate, the next level of interventioninvolves the limited replacement in kindof extensivelydeteriorated or missingpartsof features when there aresurviving prototypes (for example, brackets, dentils,steps, plaster, or portions of slate or tile roofing). Thereplacement material needs to match the old bothphysically and visually, i.e., wood with wood, etc.Thus, with the exception of hidden structural rein-forcement and new mechanical system components,substitute materials are not appropriate in the treat-ment Preservation. Again, it is important that all newmaterial be identified and properly documented forfuture research.

If prominent features are missing, such as an interiorstaircase, exterior cornice, or a roof dormer, then a

Rehabilitation or Restoration treatment may be moreappropriate.

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This three-part drawing shows the evolution of a farm house overtime. Such change is part of the history of the place and isrespected within the treatment, Preservation. Drawing: Centerfor Historic Architecture and Engineering, University ofDelaware (adapted from Preservation Brief 35: UnderstandingOld Buildings).

circa 1760

circa 1800

circa 1850


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Energy Efficiency/AccessibilityConsiderations/Health and Safety CodeConsiderations

These sections of the Preservation guidance addresswork done to meet accessibility requirements andhealth and safety code requirements; or limited retro-fitting measures to improve energy efficiency.Although this work is quite often an important aspectof preservation projects, it is usually not part of theoverall process of protecting, stabilizing, conserving,or repairing character-defining features; rather, suchwork is assessed for its potential negative impact on

the buildings character. For this reason, particularcare must be taken not to obscure, damage, or destroycharacter-defining materials or features in the processof undertaking work to meet code and energyrequirements.

Preservation as a Treatment. When the propertys dis-tinctive materials, features, and spaces are essentiallyintact and thus convey the historic significance withoutextensive repair or replacement; when depiction at a

particular period of time is not appropriate; and whena continuing or new use does not require additions orextensive alterations, Preservation may be considered asa treatment. Prior to undertaking work, a documen-tation plan for Preservation should be developed.

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Preservation


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22 Building ExteriorMasonry

RecommendedIdentifying, retaining, and preservingmasonry features thatare important in defining the overall historic character of thebuilding such as walls, brackets, railings, cornices, windowarchitraves, door pediments, steps, and columns; and detailssuch as tooling and bonding patterns, coatings, and color.

Stabilizingdeteriorated or damaged masonry as a preliminarymeasure, when necessary, prior to undertaking appropriatepreservation work.

Protecting and maintainingmasonry by providing properdrainage so that water does not stand on flat, horizontal sur-faces or accumulate in curved decorative features.

Cleaning masonry only when necessary to halt deteriorationor remove heavy soiling.

Carrying out masonry surface cleaning tests after it has beendetermined that such cleaning is appropriate. Tests should beobserved over a sufficient period of time so that both theimmediate and the long range effects are known to enableselection of the gentlest method possible.

Not Recommended

Altering masonry features which are important in definingthe overall historic character of the building so that, as aresult, the character is diminished.

Replacing historic masonry features instead of repairing orreplacing only the deteriorated masonry.

Applying paint or other coatings such as stucco to masonrythat has been historically unpainted or uncoated.

Removing paint from historically painted masonry.

Changing the type of paint or coating or its color.

Failing to stabilize deteriorated or damaged masonry untiladditional work is undertaken, thus allowing further damageto occur to the historic building.

Failing to evaluate and treat the various causes of mortar jointdeterioration such as leaking roofs or gutters, differential set-tlement of the building, capillary action, or extreme weatherexposure.

Cleaning masonry surfaces when they are not heavily soiled,thus needlessly introducing chemicals or moisture into his-toric materials.

Cleaning masonry surfaces without testing or without suffi-cient time for the testing results to be of value.

Building Exterior

Masonry: Brick, stone, terra cotta, concrete, adobe, stucco, and mortar

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Building ExteriorMasonry 23

Recommended

Cleaning masonry surfaces with the gentlest method possible,such as low pressure water and detergents, using natural bris-tle brushes.

Inspecting painted masonry surfaces to determine whetherrepainting is necessary.

Removing damaged or deteriorated paint only to the nextsound layer using the gentlest method possible (e.g., hand-scraping) prior to repainting.

Applying compatible paint coating systems following propersurface preparation.

Repainting with colors that are historically appropriate to thebuilding and district.

Evaluating the existing condition of the masonry to deter-mine whether more than protection and maintenance are

required, that is, if repairs to masonry features will be neces-sary.

Repairing, stabilizing, and conservingfragile masonry byusing well-tested consolidants, when appropriate. Repairsshould be physically and visually compatible and identifiableupon close inspection for future research.

Not Recommended

Sandblasting brick or stone surfaces using dry or wet grit orother abrasives. These methods of cleaning permanentlyerode the surface of the material and accelerate deterioration.

Using a cleaning method that involves water or liquid chemi-cal solutions when there is any possibility of freezing temper-atures.

Cleaning with chemical products that will damage masonry,such as using acid on limestone or marble, or leaving chemi-cals on masonry surfaces.

Applying high pressure water cleaning methods that willdamage historic masonry and the mortar joints.

Removing paint that is firmly adhering to, and thus protect-ing, masonry surfaces.

Using methods of removing paint which are destructive tomasonry, such as sandblasting, application of caustic solu-tions, or high pressure waterblasting.

Failing to follow manufacturers product and applicationinstructions when repainting masonry.

Using new paint colors that are inappropriate to the historicbuilding and district.

Failing to undertake adequate measures to assure the protec-tion of masonry features.

Removing masonry that could be stabilized, repaired andconserved; or using untested consolidants and untrained per-sonnel, thus causing further damage to fragile materials.

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24 Building ExteriorMasonry

Recommended

Repairing masonry walls and other masonry features byrepointing the mortar joints where there is evidence of deteri-oration such as disintegrating mortar, cracks in mortar joints,loose bricks, damp walls, or damaged plasterwork.

Removing deteriorated mortar by carefully hand-raking thejoints to avoid damaging the masonry.

Duplicating old mortar in strength, composition, color, andtexture.

Duplicating old mortar joints in width and in joint profile.

Adequate protection and maintenance of a historic building is anongoing commitment. Here, two workers are priming and repaintingexterior stone and wood trim. If surface treatments are neglected, moreextensive repair and replacement will be required. Each loss furtherundermines a buildings historic integrity.

Not Recommended

Removing nondeteriorated mortar from sound joints, thenrepointing the entire building to achieve a uniform appearance.

Using electric saws and hammers rather than hand tools toremove deteriorated mortar from joints prior to repointing.

Repointing with mortar of high portland cement content(unless it is the content of the historic mortar). This can oftencreate a bond that is stronger than the historic material and cancause damage as a result of the differing coefficient of expan-sion and the differing porosity of the material and the mortar.

Repointing with a synthetic caulking compound.

Using a scrub coating technique to repoint instead of tradi-tional repointing methods.

Changing the width or joint profile when repointing.


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Preservation


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Building Exterior Wood 27

Recommended

Using with care electric hot-air guns on decorative wood fea-tures and electric heat plates on flat wood surfaces when paintis so deteriorated that total removal is necessary prior torepainting.

Using chemical strippers primarily to supplement othermethods such as handscraping, handsanding and the above-recommended thermal devices. Detachable wooden elementssuch as shutters, doors, and columns maywith the propersafeguardsbe chemically dip-stripped.

Applying compatible paint coating systems following propersurface preparation.

Not Recommended

Using thermal devices improperly so that the historic wood-work is scorched.

Failing to neutralize the wood thoroughly after using chemi-cals so that new paint does not adhere.

Allowing detachable wood features to soak too long in a caus-tic solution so that the wood grain is raised and the surfaceroughened.

Failing to follow manufacturers product and applicationinstructions when repainting exterior woodwork.

Maximizing retention of historic materials and features is the primary goal of Preservation as demonstrated here in these before and after pho-tographs. Aside from some minor repairs and limited replacement of deteriorated material, work on this house consisted primarily of repainting the

wood exterior. Photos: Historic Charleston Foundation.

Preservation


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Recommended

Limited Replacement in Kind

Replacing in kind extensively deteriorated or missing parts ofwood features when there are surviving prototypes such asbrackets, molding, or sections of siding. New work shouldmatch the old in material, design, color, and texture; and be

unobtrusively dated to guide future research and treatment.

Not Recommended

Replacing an entire wood feature such as a column or stair-way when limited replacement of deteriorated and missingparts is appropriate.

Using replacement material that does not match the historicwood feature; or failing to properly document the new work.

28 Building Exterior Wood

The following work is highlighted to indicate that it represents the greatest degree of intervention that is generally recommended withinthe treatmentPreservation, and should only be considered after protection, stabilization, and repair concerns have been addressed.

Not Recommended

Using new colors that are inappropriate to the historic build-ing or district.

Failing to undertake adequate measures to assure the protec-tion of wood features.

Removing wood that could be stabilized and conserved; orusing untested consolidants and untrained personnel, thuscausing further damage to fragile historic materials.

Removing wood that could be repaired, using improperrepair techniques, or failing to document the new work.

Recommended

Repainting with colors that are appropriate to the historicbuilding and district.

Evaluating the existing condition of the wood to determinewhether more than protection and maintenance are required,that is, if repairs to wood features will be necessary.

Repairing, stabilizing, and conservingfragile wood usingwell-tested consolidants, when appropriate. Repairs shouldbe physically and visually compatible and identifiable uponclose inspection for future research.

Repairing wood features by patching, piecing-in, or otherwisereinforcing the wood using recognized preservation methods.The new work should be unobtrusively dated to guide futureresearch and treatment.


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Preservation

R d d N R d d


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30 Building ExteriorMetals

Recommended

Cleaning soft metals such as lead, tin, copper, terneplate, andzinc with appropriate chemical methods because their finishescan be easily abraded by blasting methods.

Using the gentlest cleaning methods for cast iron, wroughtiron, and steelhard metalsin order to remove paintbuildup and corrosion. If handscraping and wire brushinghave proven ineffective, low pressure grit blasting may beused as long as it does not abrade or damage the surface.

Applying appropriate paint or other coating systems aftercleaning in order to decrease the corrosion rate of metals oralloys.

Repainting with colors that are appropriate to the historicbuilding or district.

Applying an appropriate protective coating such as lacquer toan architectural metal feature such as a bronze door which issubject to heavy pedestrian use.

Evaluating the existing condition of the architectural metalsto determine whether more than protection and maintenanceare required, that is, if repairs to features will be necessary.

Not Recommended

Cleaning soft metals such as lead, tin, copper, terneplate, andzinc with grit blasting which will abrade the surface of themetal.

Failing to employ gentler methods prior to abrasively clean-ing cast iron, wrought iron or steel; or using high pressure gritblasting.

Failing to re-apply protective coating systems to metals oralloys that require them after cleaning so that accelerated cor-rosion occurs.

Using new colors that are inappropriate to the historic build-ing or district.

Failing to assess pedestrian use or new access patterns so thatarchitectural metal features are subject to damage by use orinappropriate maintenance such as salting adjacent sidewalks.

Failing to undertake adequate measures to assure the protec-tion of architectural metal features.

Preservation

R d d N R d d


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Building ExteriorMetals 31

Recommended

Repairing, stabilizing, and conservingfragile architecturalmetals using well-tested consolidants, when appropriate.Repairs should be physically and visually compatible and

identifiable upon close inspection for future research.

Repairing architectural metal features by patching, piecing-in,or otherwise reinforcing the metal using recognized preserva-tion methods. The new work should be unobtrusively datedto guide future research and treatment.

Not Recommended

Removing architectural metals that could be stabilized andconserved; or using untested consolidants and untrainedpersonnel, thus causing further damage to fragile historic

materials.

Removing architectural metals that could be repaired, usingimproper repair techniques, or failing to document the newwork.

Two examples of limited replacement in kind point out an appropriate scope of work within the treatment, Preservation. (a) One metal modillionthat has sustained damage from a faulty gutter will need to be replaced; and (b) targeted repairs to deteriorated wood cornice elements (fascia boardand modillions) meant that most of the historic materials were retained in the work.

Preservation

The following work is highlighted to indicate that it represents the greatest degree of intervention generally recommended within the


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32 Building ExteriorMetals

Recommended


Replacing in kind extensively deteriorated or missing parts ofarchitectural metal features when there are surviving proto-types such as porch balusters, column capitals or bases, orporch cresting. The new work should match the old in mate-rial, design, and texture; and be unobtrusively dated to guidefuture research and treatment.

The following work is highlighted to indicate that it represents the greatest degree of intervention generally recommended within thetreatmentPreservation, and should only be considered after protection, stabilization, and repair concerns have been addressed.

Not Recommended

Replacing an entire architectural metal feature such as a col-umn or balustrade when limited replacement of deterioratedand missing parts is appropriate.

Using replacement material that does not match the historicmetal feature; or failing to properly document the new work.

Preservation

Building Exterior


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Building Exterior Roofs 33

Recommended

Identifying, retaining, and preserving roofsand their func-tional and decorative featuresthat are important in definingthe overall historic character of the building. This includesthe roof s shape, such as hipped, gambrel, and mansard; dec-orative features such as cupolas, cresting, chimneys, andweathervanes; and roofing material such as slate, wood, claytile, and metal, as well as its size, color, and patterning.

Stabilizingdeteriorated or damaged roofs as a preliminarymeasure, when necessary, prior to undertaking appropriatepreservation work.

It is particularly important to preserve materials that contribute to abuildings historic character, such as this highly visible slate roof. In theevent that repair and limited replacement are necessary, all new slate

would need to match the old exactly. Photo: Jeffrey S. Levine.

Building Exterior

Roofs

Not Recommended

Altering the roof and roofing materials which are importantin defining the overall historic character of the building sothat, as a result, the character is diminished.

Replacing historic roofing material instead of repairing orreplacing only the deteriorated material.

Changing the type or color of roofing materials.

Failing to stabilize a deteriorated or damaged roof until addi-tional work is undertaken, thus allowing further damage tooccur to the historic building.


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Preservation

Building Exterior


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Building Exterior Windows 35

Recommended

Identifying, retaining, and preservingwindowsand theirfunctional and decorative featuresthat are important indefining the overall historic character of the building. Suchfeatures can include frames, sash, muntins, glazing, sills,heads, hoodmolds, panelled or decorated jambs and mold-ings, and interior and exterior shutters and blinds.

Not Recommended

Altering windows or window features which are importantin defining the historic character of the building so that, asa result, the character is diminished.

Changing the historic appearance of windows by replacingmaterials, finishes, or colors which noticeably change the sash,depth of reveal, and muntin configuration; the reflectivity andcolor of the glazing; or the appearance of the frame.

Obscuring historic window trim with metal or other material.

Building Exterior

Windows

Preserving a buildings historic windows generally involves scraping,sanding, and re-painting. While some repair work will most likely beundertaken within the scope of work on this institutional building,replacement of the window units is usually not an appropriate

Preservation treatment. Photo: Chuck Fisher.

Preservation

Recommended Not Recommended


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36 Building Exterior Windows

Conducting an indepth survey of the condition of existingwindows early in preservation planning so that repair andupgrading methods and possible replacement options can be

fully explored.

Stabilizingdeteriorated or damaged windows as a prelimi-nary measure, when necessary, prior to undertaking appropri-ate preservation work.

Protecting and maintainingthe wood and architectural met-als which comprise the window frame, sash, muntins, andsurrounds through appropriate surface treatments such as

cleaning, rust removal, limited paint removal, and re-applica-tion of protective coating systems.

Making windows weathertight by re-caulking and replacingor installing weatherstripping. These actions also improvethermal efficiency.

Evaluating the existing condition of materials to determinewhether more than protection and maintenance are required,i.e. if repairs to windows and window features will berequired.

Repairingwindow frames and sash by patching, piecing-in,consolidating or otherwise reinforcing them using recognizedpreservation methods. The new work should be unobtru-sively dated to guide future research and treatment.

Replacing windows solely because of peeling paint, brokenglass, stuck sash, and high air infiltration. These conditions,in themselves, are no indication that windows are beyond

repair.

Failing to stabilize a deteriorated or damaged window untiladditional work is undertaken, thus allowing further damageto occur to the historic building.

Failing to provide adequate protection of materials on a cyclicalbasis so that deterioration of the window results.

Retrofitting or replacing windows rather than maintaining thesash, frame, and glazing.

Failing to undertake adequate measures to assure the protectionof historic windows.

Failing to protect the historic glazing when repairing windows.

Removing material that could be repaired, using improperrepair techniques, or failing to document the new work.

Failing to reuse serviceable window hardware such as brass sash

lifts and sash locks.

Preservation

The following work is highlighted to indicate that it represents the greatest degree of intervention generally recommended within the


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Building Exterior Windows 37

Recommended


Replacing in kind extensively deteriorated or missing parts ofwindows when there are surviving prototypes such as frames,sash, sills, glazing, and hoodmolds. The new work shouldmatch the old in material, design, color, and texture; and beunobtrusively dated to guide future research and treatment.

Not Recommended

Replacing an entire window when limited replacement ofdeteriorated and missing parts is appropriate.

Using replacement material that does not match the historicwindow; or failing to properly document the new work.

f g g g p g g f g ytreatmentPreservation, and should only be considered after protection, stabilization, and repair concerns have been addressed.

Preservation

Building Exterior


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38 Building Exterior Entrances and Porches

g


RecommendedIdentifying, retaining, and preservingentrances and porchesand their functional and decorative featuresthat are impor-tant in defining the overall historic character of the buildingsuch as doors, fanlights, sidelights, pilasters, entablatures,columns, balustrades, and stairs.

Stabilizingdeteriorated or damaged entrances and porches as

a preliminary measure, when necessary, prior to undertakingappropriate preservation work.

Protecting and maintainingthe masonry, wood, and architec-tural metals that comprise entrances and porches throughappropriate surface treatments such as cleaning, rust removal,limited paint removal, and re-application of protective coatingsystems.

Evaluating the existing condition of materials to determinewhether more than protection and maintenance are required,that is, repairs to entrance and porch features will be necessary.

Repairingentrances and porches by reinforcing the historicmaterials using recognized preservation methods. The newwork should be unobtrusively dated to guide future researchand treatment.

Not RecommendedAltering entrances and porches which are important indefining the overall historic character of the building sothat, as a result, the character is diminished.

Replacing historic entrance and porch features instead ofrepairing or replacing only the deteriorated material.

Failing to stabilize a deteriorated or damaged entrance orporch until additional work is undertaken, thus allowingfurther damage to occur to the historic building.

Failing to provide adequate protection to materials on acyclical basis so that deterioration of entrances and porchesresults.

Failing to undertake adequate measures to assure the protec-tion of historic entrances and porches.


Preservation

The following work is highlighted to indicate that it represents the greatest degree of intervention generally recommended within thed h ld l b d d f b l d h b dd d


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Recommended

Replacing in kind extensively deteriorated or missing parts ofrepeated entrance and porch features when there are surviv-ing prototypes such as balustrades, cornices, entablatures,columns, sidelights, and stairs. The new work should matchthe old in material, design, color, and texture; and be unob-trusively dated to guide future research and treatment.

Not Recommended

Replacing an entire entrance or porch feature when limitedreplacement of deteriorated and missing parts is appropriate.

Using replacement material that does not match the historicentrance or porch feature; or failing to properly documentthe new work.

Building Exterior Entrances and Porches 39

treatmentPreservation, and should only be considered after protection, stabilization, and repair concerns have been addressed.

Preservation

Building Exterior


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40 Building Exterior Storefronts

Storefronts

RecommendedIdentifying, retaining, and preservingstorefrontsand theirfunctional and decorative featuresthat are important indefining the overall historic character of the building such asdisplay windows, signs, doors, transoms, kick plates, cornerposts, and entablatures.

Stabilizingdeteriorated or damaged storefronts as a prelimi-nary measure, when necessary, prior to undertaking appropri-ate preservation work.

Not RecommendedAltering storefrontsand their featureswhich are impor-tant in defining the overall historic character of the buildingso that, as a result, the character is diminished.

Replacing historic storefront features instead of repairing orreplacing only the deteriorated material.

Failing to stabilize a deteriorated or damaged storefront untiladditional work is undertaken, thus allowing further damageto occur to the historic building.

The original form and features of this 1920s storefront have beenretained through Preservation. Photo: David W. Look, AIA.

Preservation



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Recommended


Replacing in kind extensively deteriorated or missing parts ofstorefronts where there are surviving prototypes such as tran-soms, kick plates, pilasters, or signs. The new work shouldmatch the old in materials, design, color, and texture; and beunobtrusively dated to guide future research and treatment.

Not Recommended

Replacing an entire storefront when limited replacement ofdeteriorated and missing parts is appropriate.

Using replacement material that does not match the historicstorefront feature; or failing to properly document the newwork.

Building Exterior Storefronts 41


Protecting and maintainingmasonry, wood, and architectur-al metals which comprise storefronts through appropriatetreatments such as cleaning, rust removal, limited paint

removal, and reapplication of protective coating systems.

Protecting storefronts against arson and vandalism beforework begins by boarding up windows and doors andinstalling alarm systems that are keyed into local protectionagencies.

Evaluating the existing condition of storefront materials todetermine whether more than protection and maintenanceare required, that is, if repairs to features will be necessary.

Repairingstorefronts by reinforcing the historic materialsusing recognized preservation methods. The new workshould be unobtrusively dated to guide future research andtreatment.

Failing to provide adequate protection of materials on a cycli-cal basis so that deterioration of storefront features results.

Permitting entry into the building through unsecured or bro-ken windows and doors so that interior features and finishesare damaged by exposure to weather or vandalism.

Stripping storefronts of historic material such as wood, castiron, terra cotta, carrara glass, and brick.

Failing to undertake adequate measures to assure the preser-vation of the historic storefront.


Preservation

Building Interior


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42 Building Interior Structural Systems

Structural Systems

Recommended

Identifying, retaining, and preservingstructural systemsand individual features of systemsthat are important indefining the overall historic character of the building, such aspost and beam systems, trusses, summer beams, vigas, castiron columns, above-grade stone foundation walls, or load-bearing brick or stone walls.

Stabilizingdeteriorated or damaged structural systems as apreliminary measure, when necessary, prior to undertakingappropriate preservation work.

Protecting and maintainingthe structural system by cleaningthe roof gutters and downspouts; replacing roof flashing;keeping masonry, wood, and architectural metals in a sound

condition; and ensuring that structural members are freefrom insect infestation.

Examining and evaluating the existing condition of the struc-tural system and its individual features using non-destructivetechniques such as X-ray photography.

Not Recommended

Altering visible features of historic structural systems whichare important in defining the overall historic character of thebuilding so that, as a result, the character is diminished.

Overloading the existing structural system; or installingequipment or mechanical systems which could damage thestructure.

Replacing a loadbearing masonry wall that could be aug-mented and retained.

Leaving known structural problems untreated such as deflec-tion of beams, cracking and bowing of walls, or racking ofstructural members.

Utilizing treatments or products that accelerate the deteriora-tion of structural material such as introducing urea-formalde-

hyde foam insulation into frame walls.

Failing to stabilize a deteriorated or damaged structural sys-tem until additional work is undertaken, thus allowing fur-ther damage to occur to the historic building.

Failing to provide proper building maintenance so that dete-rioration of the structural system results. Causes of deteriora-tion include subsurface ground movement, vegetation grow-

ing too close to foundation walls, improper grading, fungalrot, and poor interior ventilation that results in condensation.

Utilizing destructive probing techniques that will damage ordestroy structural material.

Preservation

Not RecommendedRecommended


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Building Interior Structural Systems 43

Upgrading the building structurally in a manner that dimin-ishes the historic character of the exterior, such as installingstrapping channels or removing a decorative cornice; or dam-

ages interior features or spaces.

Replacing a structural member or other feature of the struc-tural system when it could be augmented and retained.

Not Recommended

Replacing an entire visible feature of the structural systemwhen limited replacement of deteriorated and missing por-tions is appropriate.

Using material for a portion of an exposed structural feature

that does not match the historic feature; or failing to properlydocument the new work.

Using substitute material that does not equal the loadbearingcapabilities of the historic material or design or is otherwisephysically or chemically incompatible.

Repairingthe structural system by augmenting or upgradingindividual parts or features using recognized preservationmethods. For example, weakened structural members such as

floor framing can be paired with a new member, braced, orotherwise supplemented and reinforced.

Recommended


Replacing in kind those visible portions or features of thestructural system that are either extensively deteriorated ormissing when there are surviving prototypes such as cast ironcolumns and sections of loadbearing walls. The new workshould match the old in materials, design, color, and texture;and be unobtrusively dated to guide future research and treat-ment.

Considering the use of substitute material for unexposedstructural replacements, such as roof rafters or trusses.Substitute material should, at a minimum, have equal load-bearing capabilities, and be unobtrusively dated to guidefuture research and treatment.

The following work is highlighted to indicate that it represents the greatest degree of intervention generally recommended within thetreatmentPreservation and should be only be considered after protection, stabilization, and repair concerns have been addressed.

Preservation

Building Interior


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44 Building Interior Spaces, Features, and Finishes

Spaces, Features, and Finishes

Recommended

Interior Spaces

Identifying, retaining, and preservinga floor plan or interiorspaces that are important in defining the overall historic char-acter of the building. This includes the size, configuration,proportion, and relationship of rooms and corridors; the rela-tionship of features to spaces; and the spaces themselves suchas lobbies, reception halls, entrance halls, double parlors, the-aters, auditoriums, and important industrial or commercialspaces.

Not Recommended

Altering a floor plan or interior spacesincluding individualroomswhich are important in defining the overall historiccharacter of the building so that, as a result, the character isdiminished.

Careful documentation of a buildings physical condition is the criticalfirst step in determining an appropriate level of intervention. (a) Thismay include relating the historical research to existing materials and

features; or (b) documenting a particular problem such as this cracked

ceiling. Photo (a): Jean E. Travers; Photo (b): Lee H. Nelson, FAIA.

Preservation

Recommended

I i F d Fi i h

Not Recommended


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Interior Features and Finishes

Identifying, retaining, and preservinginterior features and

finishes that are important in defining the overall historiccharacter of the building, including columns, cornices, base-boards, fireplaces and mantels, panelling, light fixtures, hard-ware, and flooring; and wallpaper, plaster, paint, and finishessuch as stencilling, marbling, and graining; and other decora-tive materials that accent interior features and provide color,texture, and patterning to walls, floors, and ceilings.

Stabilizingdeteriorated or damaged interior features andfinishes as a preliminary measure, when necessary, priorto undertaking appropriate preservation work.

Protecting and maintainingmasonry, wood, and architec-tural metals that comprise interior features through appro-

priate surface treatments such as cleaning, rust removal,limited paint removal, and reapplication of protective coatingsystems.

Building Interior Spaces, Features, and Finishes 45

Altering features and finishes which are important in defining

the overall historic character of the building so that, as aresult, the character is diminished.

Replacing historic interior features and finishes instead ofrepairing or replacing only the deteriorated masonry.

Installing new decorative material that obscures or damagescharacter-defining interior features or finishes.

Removing historic finishes, such as paint and plaster, or his-toric wall coverings, such as wallpaper.

Applying paint, plaster, or other finishes to surfaces that havebeen historically unfinished.

Stripping paint to bare wood rather than repairing or reapply-ing grained or marbled finishes to features such as doors andpaneling.

Changing the type of finish or its color, such as painting apreviously varnished wood feature.

Failing to stabilize a deteriorated or damaged interior featureor finish until additional work is undertaken, thus allowingfurther damage to occur to the historic building.

Failing to provide adequate protection to materials on a cycli-cal basis so that deterioration of interior features results.


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Preservation

Not Recommended

Removing materials that could be repaired using improper

Recommended

Repairing historic interior features and finishes by reinforcing


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Building Interior Spaces, Features, and Finishes 47

Removing materials that could be repaired, using impropertechniques, or failing to document the new work.

Repairinghistoric interior features and finishes by reinforcingthe materials using recognized preservation methods. Thenew work should match the old in material, design, color,

and texture; and be unobtrusively dated to guide futureresearch and treatment.

In Preservation, an appropriate level of intervention is established prior to work in order to maximize retention of historic materials.

(a) A conservator is applying adhesive to 19th century composition ornament that has delaminated from its wood substrate.(b) The compo fragment is carefully held in place until the quick-setting adhesive takes hold. Photos: Jonathan Thornton.

Preservation



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48 Building Interior Spaces, Features, and Finishes

Recommended


Replacing in kind extensively deteriorated or missing parts ofrepeated interior features when there are surviving prototypessuch as stairs, balustrades, wood panelling, columns; or deco-rative wall coverings or ornamental tin or plaster ceilings.New work should match the old in material, design, color,and texture; and be unobtrusively dated to guide future

research and treatment.

Not Recommended

Replacing an entire interior feature when limited replacementof deteriorated and missing parts is appropriate.

Using replacement material that does not match the interiorfeature; or failing to properly document the new work.

Preservation

Building Interior

Mechanical Systems: Heating Air Conditioning Electrical and Plumbing


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Building InteriorMechanical Systems 49

Recommended

Identifying, retaining, and preservingvisible features of earlymechanical systems that are important in defining the overallhistoric character of the building, such as radiators, vents,fans, grilles, plumbing fixtures, switchplates, and lights.

Stabilizingdeteriorated or damaged mechanical systems as apreliminary measure, when necessary, prior to undertakingappropriate preservation work.

Protecting and maintainingmechanical, plumbing, and elec-trical systems and their features through cyclical cleaning andother appropriate measures.

Preventing accelerated deterioration of mechanical systems byproviding adequate ventilation of attics, crawlspaces, and cel-lars so that moisture problems are avoided.

Improving the energy efficiency of existing mechanical sys-tems to help reduce the need for elaborate new equipment.

Repairingmechanical systems by augmenting or upgradingsystem parts, such as installing new pipes and ducts; rewiring;

or adding new compressors or boilers.Replacingin kind those visible features of mechanical systemsthat are either extensively deteriorated or are prototypes suchas ceiling fans, switchplates, radiators, grilles, or plumbingfixtures.

Mechanical Systems: Heating, Air Conditioning, Electrical, and Plumbing

Not Recommended

Removing or altering visible features of mechanical systemsthat are important in defining the overall historic character ofthe building so that, as a result, the character is diminished.

Failing to stabilize a deteriorated or damaged mechanical sys-tem until additional work is undertaken, thus allowing fur-ther damage to occur to the historic building.

Failing to provide adequate protection of materials on a cycli-cal basis so that deterioration of mechanical systems and theirvisible features results.

Enclosing mechanical systems in areas that are not adequatelyventilated so that deterioration of the systems results.

Installing unnecessary climate control systems which can addexcessive moisture to the building. This additional moisturecan either condense inside, damaging interior surfaces, orpass through interior walls to the exterior, potentially damag-ing adjacent materials as it migrates.

Replacing a mechanical system or its functional parts when itcould be upgraded and retained.

Installing a visible replacement feature that does not conveythe same visual appearance.

Preservation

The following should be considered in a Preservationproject when the installation of new mechanical equipment or system is requiredto make the building functional.


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50 Building InteriorMechanical Systems

Recommended

Installing a new mechanical system if required, so that it caus-es the least alteration possible to the building.

Providing adequate structural support for new mechanicalequipment.

Installing the vertical runs of ducts, pipes, and cables in clos-ets, service rooms, and wall cavities.

Installing air conditioning in such a manner that historic fea-tures are not damaged or obscured and excessive moisture is

not generated that will accelerate deterioration of historicmaterials.

Not Recommended

Installing a new mechanical system so that character-definingstructural or interior features are radically changed, damaged,or destroyed.

Failing to consider the weight and design of new mechanicalequipment so that, as a result, historic structural members orfinished surfaces are weakened or cracked.

Installing vertical runs of ducts, pipes, and cables in placeswhere they will obscure character-defining features.

Concealing mechanical equipment in walls or ceilings in amanner that requires excessive removal of historic buildingmaterial.

Cutting through features such as masonry walls in order toinstall air conditioning units.

Preservation

Building Site



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Building Site 51

Recommended

Identifying, retaining, and preservingbuildings and their fea-

tures as well as features of the site that are important in defin-ing its overall historic character. Site features may include cir-culation systems such as walks, paths, roads, or parking; vege-tation such as trees, shrubs, fields, or herbaceous plant mater-ial; landforms such as terracing, berms or grading; furnishingssuch as lights, fences, or benches; decorative elements such assculpture, statuary or monuments; water features includingfountains, streams, pools, or lakes; and subsurface archeologi-

cal features which are important in defining the history of thesite.

Retaining the historic relationship between buildings and thelandscape.

Stabilizingdeteriorated or damaged building and site featuresas a preliminary measure, when necessary, prior to undertak-

ing appropriate preservation work.

Not Recommended

Altering buildings and their features or site features which are

important in defining the overall historic character of theproperty so that, as a result, the character is diminished.

Removing or relocating buildings or landscape features, thusdestroying the historic relationship between buildings and thelandscape.

Failing to stabilize a deteriorated or damaged building or sitefeature until additional work is undertaken, thus allowing

further damage to occur to the building site.

Drayton Hall, near Charleston, South Carolina, is an excellent exam-ple of an evolved 18th century plantation. Of particular note in thisphotograph are the landscape features added in the late 19th centurya reflecting pond and rose mound. With an overall Preservation treat-ment plan, these later features have been retained and protected. If aRestoration treatment had been selected, later features of the landscapeas well as changes to the house would have been removed. Photo:

Courtesy, National Trust for Historic Preservation.


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Preservation

Recommended

Evaluating the existing condition of materials and features tod i h h h i d i

Not Recommended

Failing to undertake adequate measures to assure the protec-i f b ildi d i f


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Building Site 53

determine whether more than protection and maintenanceare required, that is, if repairs to building and site features will

be necessary.Repairingfeatures of the building and site by reinforcing his-toric materials using recognized preservation methods. Thenew work should be unobtrusively dated to guide futureresearch and treatment.

Recommended


Replacing in kind extensively deteriorated or missing parts of

the building or site where there are surviving prototypes suchas part of a fountain, or portions of a walkway. New workshould match the old in materials, design, color, and texture;and be unobtrusively dated to guide future research and treat-ment.

tion of building and site features.

Removing materials that could be repaired, using improperrepair techniques, or failing to document the new work.

Not Recommended

Replacing an entire feature of the building or site when limit-

ed replacement of deteriorated and missing parts is appropri-ate.

Using replacement material that does not match the buildingsite feature; or failing to properly document the new work.



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Preservation

Recommended

Repairingfeatures of the building and landscape using recog-nized preservation methods The new work should be unob

Not Recommended

Removing material that could be repaired, using improperrepair techniques or failing to document the new work


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Setting 55

nized preservation methods. The new work should be unob-trusively dated to guide future research and treatment.

Recommended


Replacing in kind extensively deteriorated or missing parts ofbuilding and landscape features where there are survivingprototypes such as porch balustrades or paving materials.

repair techniques, or failing to document the new work.

Not Recommended

Replacing an entire feature of the building or landscape whenlimited replacement of deteriorated and missing parts isappropriate.

Using replacement material that does not match the buildingor landscape feature; or failing to properly document the newwork.

The following work is highlighted because it represents the greatest degree of intervention generally recommended within the treatmentPreservation, and should only be considered after protection, stabilization, and repair concerns have been addressed.

The goal of Preservation is to retain the historic form, materials,and features of the building and its site as they have changedorevolvedover time. This bank barn was built in the 1820s, thenenlarged in 1898 and again in 1914. Today, it continues its roleas a working farm structure as a result of sensitive preservation work.This included foundation re-grading; a new gutter system; structuralstrengthening; and replacement of a severely deteriorated metal roof.

Photo: Jack E. Boucher, HABS.

Preservation

Although the work in the following sections is quite often an important aspect of preservation projects, it is usually not part of theoverall process of preserving character-defining features (maintenance, repair, and limited replacement); rather, such work is assessed

for its potential negative impact on the buildings historic character. For this reason, particular care must be taken not to obscure,


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56 Energy Efficiency

Energy Efficiency

Recommended

Masonry/Wood/Architectural Metals

Installing thermal insulation in attics and in unheated cellarsand crawlspaces to increase the efficiency of the existingmechanical systems.

Installing insulating material on the inside of masonry wallsto increase energy efficiency where there is no character-defining interior molding around the windows or other inte-rior architectural detailing.

Windows

Utilizing the inherent energy conserving features of a build-

ing by maintaining windows and louvered blinds in goodoperable condition for natural ventilation.

Improving thermal efficiency with weatherstripping, stormwindows, caulking, interior shades, and if historically appro-priate, blinds and awnings.

Installing interior storm windows with air-tight gaskets, ven-tilating holes, and/or removable clips to insure proper main-

tenance and to avoid condensation damage to historic win-dows.

Installing exterior storm windows which do not damage orobscure the windows and frames.

f p g p g palter, or damage character-defining features in the process of preservation work.

Not Recommended

Applying thermal insulation with a high moisture content inwall cavities which may damage historic fabric.

Installing wall insulation without considering its effect on inte-rior molding or other architectural detailing.

Removing historic shading devices rather than keeping them in

an operable condition.

Replacing historic multi-paned sash with new thermal sash uti-lizing false muntins.

Installing interior storm windows that allow moisture to accu-mulate and damage the window.

Installing new exterior storm windows which are inappropriatein size or color.

Replacing windows or transoms with fixed thermal glazing orpermitting windows and transoms to remain inoperable rather

than utilizing them for their energy conserving potential.

Preservation

Recommended


Not Recommended


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Energy Efficiency 57

Maintaining porches and double vestibule entrances so thatthey can retain heat or block the sun and provide natural ven-tilation.

Interior Features

Retaining historic interior shutters and transoms for theirinherent energy conserving features.

Mechanical Systems

Improving energy efficiency of existing mechanical systemsby installing insulation in attics and basements.

Building Site

Retaining plant materials, trees, and landscape features whichperform passive solar energy functions such as sun shadingand wind breaks.

Setting(District/Neighborhood)

Maintaining those existing landscape features which moder-ate the effects of the climate on the setting such as deciduoustrees, evergreen wind-blocks, and lakes or ponds.

Changing the historic appearance of the building by enclos-ing porches.

Removing historic interior features which play an energy con-serving role.

Replacing existing mechanical systems that could be repairedfor continued use.

Removing plant materials, trees, and landscape features thatperform passive solar energy functions.

Stripping the setting of landscape features and landforms sothat the effects of wind, rain, and sun result in accelerateddeterioration of the historic building.

Preservation

Accessibility Considerations



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58 Accessibility Considerations

Identifying the historic buildings character-defining spaces,

features, and finishes so that accessibility code-required workwill not result in their damage or loss.

Complying with barrier-free access requirements, in such amanner that character-defining spaces, features, and finishesare preserved.

Working with local disability groups, access specialists, andhistoric preservation specialists to determine the most appro-

priate solution to access problems.Providing barrier-free access that promotes independence forthe disabled person to the highest degree practicable, whilepreserving significant historic features.

Finding solutions to meet accessibility requirements thatminimize the impact on the historic building and its site,such as compatible ramps, paths, and lifts.

Undertaking code-required alterations before identifying

those spaces, features, or finishes which are character-definingand must therefore be preserved.

Altering, damaging, or destroying character-defining featuresin attempting to comply with accessibility requirements.

Making changes to buildings without first seeking expertadvice from access specialists and historic preservationists to

determine solutions.Making access modifications that do not provide a reasonablebalance between independent, safe access and preservation ofhistoric features.

Making modifications for accessibility without consideringthe impact on the historic building and its site.


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Standards forRehabilitation

&Guidelines forRehabilitatingHistoric Buildings

Rehabilitation is defined as the act or process of making pos-sible a compatible use for a property through repair, alter-ations, and additions while preserving those portions or fea-tures which convey its historical, cultural, or architecturalvalues.

Standards for Rehabilitation

1. A property will be used as it was historically or be given a new use that requires minimal change to its

distinctive materials features spaces and spatial relationships


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distinctive materials, features, spaces, and spatial relationships.2. The historic character of a property will be retained and preserved. The removal of distinctive materi-als or alteration of features, spaces, and spatial relationships that characterize a property will be avoided.

3. Each property will be recognized as a physical record of its time, place, and use. Changes that create afalse sense of historical development, such as adding conjectural features or elements from other historicproperties, will not be undertaken.

4. Changes to a property that have acquired historic significance in their own right will be retained andpreserved.

5. Distinctive materials, features, finishes, and construction techniques or examples of craftsmanship thatcharacterize a property will be preserved.

6. Deteriorated historic features will be repaired rather than replaced. Where the severity of deteriorationrequires replacement of a distinctive feature, the new feature will match the old in design, color, texture,and, where possible, materials. Replacement of missing features will be substantiated by documentaryand physical evidence.

7. Chemical or physical treatments, if appropriate, will be undertaken using the gentlest means possible.

Treatments that cause damage to historic materials will not be used.

8. Archeological resources will be protected and preserved in place. If such resources must be disturbed,mitigation measures will be undertaken.

9. New additions, exterior alterations, or related new construction will not destroy historic materials, fea-tures, and spatial relationships that characterize the property. The new work shall be differentiated fromthe old and will be compatible with the historic materials, features, size, scale and proportion, and mass-ing to protect the integrity of the property and its environment.

10. New additions and adjacent or related new construction will be undertaken in a such a manner that,if removed in the future, the essential form and integrity of the historic property and its envir

Documents

Standards Complete