Guidelines for Access Scaffolding

9/6/2014 Guidelines for Access Scaffolding

http://ewi.s5.com/scaffoldsafetyguidelines.htm 1/19

Free Web Hosting Provider - Web Hosting - E-commerce - High Speed Internet - Free Web Page

(Back to the EWI Main Safety Page)

Find more publications on Workplace Safety from Manitoba Canada

This excellent safety guideline comes from the government of Manitoba, Canada

GUIDELINES FOR ACCESSSCAFFOLDING

OSH Engineering Unit July 1997

An access scaffold is a temporary structure usually made of metal frames and tubing, which provides temporary supportand access for workers and materials used in construction, demolition, repair and maintenance work. Scaffolding, whennot constructed and used properly, can result in serious injury, and sometimes death. In Manitoba, over 7,000 workdays are lost annually as a result of scaffold-related accidents.

This guideline is intended to provide information for employers and workers on the safe erection, use and maintenanceof access scaffolding in the workplace. It is intended to provide practical information related to the requirements of theregulations pertaining to scaffolding. For specific regulatory requirements regarding scaffolds, please consult theregulations adopted under the Workplace Safety and Health Act.

Some of the information and illustrations in this guideline are based on information provided courtesy of the Construction Safety Association ofOntario (CSAO)

T A B L E O F C O N T E N T SA. RESPONSIBILITIES/DESIGN APPROVALS

B. SCAFFOLD TYPES AND SELECTION

C. SCAFFOLD FOUNDATION AND SUPPORT

D. SCAFFOLD ERECTION AND BRACING

E. SCAFFOLD ACCESS

F. SCAFFOLD WORK PLATFORMS

Search the Web

http://www.freeservers.com/?refcd=WSUOWS020722NB01

http://www.globalservers.com/?refcd=WSUOWS020722NB01

http://www.bizhosting.com/?refcd=WSUOWS020722NB01

http://www.netzero.com/?refcd=MWS0404NWP11

http://www.freeservers.com/Free-Web-Page.html?refcd=WSUOWS020722NB01

http://s5.com/?refcd=MWS_20040713_Banner_bar

http://ewi.s5.com/cgi-bin/login

http://phoenix.untd.com/TRCK/CLCK//webservices/general/40596559/Top/default/empty.gif/4a644b6c6a31514c506863414478686a?x

http://phoenix.untd.com/TRCK/CLCK//webservices/general/1413204059/Top1/default/empty.gif/4a644b6c6a31514c506863414478686a?x



G. GUARDRAILS

H. SCAFFOLD STABILITY

I. USE AND MAINTENANCE

J. INSPECTION

GLOSSARY OF TERMS

TABLE 1 - APPROX. WEIGHTS OF BUILDING MATERIALS

A. Responsibilties/Design Approvals

Employers

It is the employer’s responsibility to ensure that proper scaffolding material and equipment is provided at the projectsite. In addition, all workers must be trained in proper scaffold use, erection, and maintenance. The workers shall beinstructed on the safe working load that the scaffold is intended to carry. The employer is required to provide allnecessary personal protective equipment,(i.e. safety headwear, footwear, fall protection systems, etc.) to workerserecting and using the scaffold.

If scaffolds are designed by a professional engineer, the employer must ensure that they are constructed in accordancewith the design.

The employer must appoint a skilled and experienced worker to supervise the erection, use and dismantling of thescaffold system. This is to ensure that the correct procedures are followed, especially if specialized design andengineered drawings are required.

Principal Contractors have the overall responsibility on a project to ensure that scaffolding is erected and maintained inaccordance with regulatory requirements and good practice.

Workers

Workers must ensure that they follow safe work procedures and use all necessary equipment and any necessarypersonal protective devices when erecting and using scaffold systems. Workers must also take care to protect otherworkers when working on scaffolding.

All workers must be equipped with and use safety footwear and headwear when erecting and working on a scaffoldsystem. When practicable, proper fall protection systems should be incorporated into the erection and dismantling ofscaffold systems.

Supervision

Scaffolds must always be erected under the supervision of a worker experienced in their construction and use. Althoughscaffold systems vary between manufacturers, certain fundamental requirements are common to all scaffold systems.The supervisor is able to be on-site and confirm that the scaffold is erected in accordance with the manufacturer’srecommendations and/or engineer’s design.

Design Approvals

All open access scaffolding in excess of 15 metres (50 ft) in height must be designed by a professional engineer, anderected, used and maintained in accordance with the engineered design. If the scaffolding is to be enclosed or hoarded,then an engineer must be consulted for the design and erection of all hoarded scaffolding greater than 7.5m (25 ft.) inheight.

Engineer designed scaffold drawings and specifications shall include complete information on such details as tie-backspecifications, design load and wind loading criteria, foundation details, and design criteria for wind load on enclosedor hoarded scaffolds. The design must include all design details related to the application of the scaffolding system. Forexample, if the scaffold is to be tied-back to the structure, it must be clear whether the design includes provision for thehoarding of the scaffold.

The employer shall ensure that the engineered scaffold system is inspected, by a professional engineer, after its erectionand prior to worker use. This is to ensure that the scaffold has been erected in accordance with the design specifications.A copy of the design drawings must be kept at the project site and a written record of the engineer’s inspection providedto the employer.

Inspections

The employer shall ensure that all scaffolding systems are inspected prior to workers utilizing the system and whenwork from the scaffolding is suspended for periods of two (2) days or more, or during periods of severe weatherconditions, the scaffold system shall be inspected on a regular schedule and a record of the inspections maintained atthe job site.



CSA Standard

The applicable reference standard for access scaffolding is CSA S269.2-M87 "Access Scaffolding for ConstructionPurposes". This standard provides detailed criteria for the design of access scaffolding, including loads and forces,structural analysis and design, erection, dismantling, safety requirements, maintenance and test procedures.

Manitoba regulations pertaining to access scaffolding take precedence over any provision in the CSA standard that maydiffer from regulatory requirements.

STANDARD FRAME SCAFFOLD

B. SCAFFOLD TYPE AND SELECTION

Selecting a Scaffolding System

The safe and efficient use of scaffolding depends, first of all, on choosing the right system for the job. If the scaffold’sbasic characteristics are unsuited to the task, or if all the necessary components are not available, proper erection anduse is compromised.

Selection of scaffolding and related components requires an understanding of site conditions and the work to beundertaken. The employer must consider the following:

Basic Considerations:

-the weight of workers, tools, materials and equipment to be carried by the scaffold system (safe work load)

-site conditions (interior, exterior, backfill, concrete floors, type and condition of walls, access for the equipment,variations in elevation, anchorage points, etc)

-height to which the scaffold may be erected (overhead power lines, tie-backs)

-type of work that will be done from the scaffold (masonry work, sandblasting, painting, metal siding, mechanicalinstallation, suspended ceiling installation)

-duration of work

-weather conditions, including wind and ice build-up

-requirements for pedestrian traffic through and under the scaffold area

-means of access to the scaffold

-configuration of the building or structure being worked on

-special erection or dismantling circumstances.

-hoarding

BASIC TYPES OF SCAFFOLDS

Standard Tubular Frame Scaffold

This is the most frequently used scaffolding system in construction in Manitoba. It is made of steel tubing or aluminumand is manufactured in various configurations and spans.



The advantage of this type of scaffold is its portability and relative ease of assembly. Its main disadvantage is the factthat, because it is made up of component parts, all the parts may not be at the site or someone decides that they are notall required.

It is essential with steel frame scaffolds that all components and parts are installed properly, especially all connectionsand bracing components, base plates, work platforms and tie-backs.

The spans in frame scaffolds normally range from 1.5 metres (5 ft) to 3 metres (10 ft) These span lengths are variedusing different lengths of bracing. Most manufacturers have braces which will provide spans between 1.5 metres (5 ft)and 3 metres (10 ft) in length. However, some manufacturers have special braces both shorter and longer than thisrange.

Walk -Through (Masonry) Frame Scaffold

The standard walk-through frame scaffold is a variation of the standard tubular frame type. It is designed toaccommodate pedestrian traffic at the ground or street level and is frequently used by the masonry trade to provide



greater height per tier and easier movement and distribution of materials on platforms.

There is a tendency to overload this type of scaffold, or not provide the proper width or amount of work platformsupport. Consideration must also be given to pedestrian safety. All employers shall ensure pedestrians are protectedfrom falling debris and materials.

Rolling Scaffolds

Scaffolds which need to be moved frequently are often equipped with castors or wheels. The most importantconsideration with these scaffolds is that both horizontal and vertical bracing must be used with the standard tubularframe systems. Also, outrigger supports may have to be provided to ensure the stability of the scaffold.

Rolling scaffolds must be erected so that the height-to-base width ratio is no greater than 3 to 1. This limits platformheight with standard outrigger stabilizers and single span towers to approximately 9.5 metres (30 ft), [this assumesoutrigger stabilizers are 3 metres (10 ft across)].

Castors on rolling scaffolds must be equipped with braking devices. The type of castor used should not only include abraking device but must also be selected based upon the loads under which it will be operating. Additionally, theground surface upon which the castor will be used must be free of defects such as potholes and other obstructive debris,which may cause the scaffold to topple when it is being moved.

NOTE: No worker may "ride" the scaffold when it is being moved from one location to the other, unless the worker issecured to the building in a manner to prevent the worker from falling, if the scaffold overturned or became unstable.



F arm Wagon Type

Scaffolds erected on farm wagons or other devices with pneumatic tires are frequently used for exterior buildingapplications where movement of the scaffold is necessary. For safe, effective use, the area around the building shouldbe well compacted, relatively smooth and level. The farm wagon type scaffold is subject to the 3 to 1 height-to-widthratio, and is rarely practical for platform heights greater than 8.5 metres (28 ft).

This type of scaffold should be equipped with outrigger beams with levelling devices. If such stabilizers can not be used,a means must be provided to ensure the stability of the scaffold should any tire deflate or lose pressure. ( i.e. suitablestructural blocking under the wagon axles)

Fold-Up Scaffold Frames

Fold-up scaffold frames are frequently used by trades such as electricians, painters and suspended ceiling workers.Widths range from 330 mm (13 ") to the standard width of about 1.5 metres (5 ft). Frequently made of aluminum, thistype of scaffold is easily and quickly transported, erected and moved about construction sites and from job to job. Itshould be used only on a smooth, hard surface and equipped with a fully decked work platform, and castors equippedwith brakes.

Adjustable Scaffolds (Baker Scaffold)

Adjustable platform height scaffolds are a different variation on the fold-up scaffolds. Adjustable scaffolds arelightweight and easily adjusted for height considerations. It also has a minimum number of components, which makes iteasily transportable from job to job.

These devices should ONLY be used on smooth, hard surfaces and are not intended to carry heavy loads.

Tube-And-Clamp (Coupler) Scaffolds

This scaffolding system consists of individual aluminum or steel tubes or pipes, serving as posts, braces, ties, etc.,which are joined together in the field by means of special clamps or couplers, to form an integral load-carrying structurefor the support of workers, equipment and materials.

Tube-and-Clamp scaffolds are frequently used where obstructions or non-rectangular structures are encountered. Thescaffolds are infinitely adjustable in height and width. They can also be used for irregular and circular verticalconfigurations.

Workers erecting tube-and-clamp scaffolds must be trained and experienced. For each set-up, a sketch or drawingshould be prepared by an experienced person skilled in this type of system. The requirement for engineer’s approvalsalso apply to tube and clamp access scaffolding.



C. SCAFFOLD FOUNDATION AND SUPPORT

Scaffolds must be erected on surfaces which can adequately support all loads applied by the scaffold. To supportscaffolds, backfilled soils must be well compacted and levelled. Mud and soft soil should be replaced with compactedgravel or crushed stone. Embankments that appear unstable or susceptible to erosion must be contained.

Where mudsills must be placed on sloping ground, levelling the area should be done by excavating, rather thanbackfilling. Backfilled material, unless properly compacted and levelled, does not have the same capacity to support aload as undisturbed soil.

For sloped surfaces, it may be necessary to use half-frames to accommodate the grade change. For these situations thebracing is usually provided by using tube-and-clamp components.

Scaffolds erected on any type of soil or gravel, etc. must be supported on a mudsill . The mudsill must be a minimum of50 mm x 250 mm (2" x 10") S-P-F plank and must be continuous under at least two consecutive end-frames orsupports. For frame scaffolds, there must be proper base plates with adjustable screw jacks under each post support,when the frames are supported on a smooth concrete surface. A proper base plate is required under all circumstances.The base plate should rest centrally on the mudsill and the sill should project at least 600 mm (2 ft) beyond the scaffoldfoot ends or where individual sills butt together. Mudsills should be placed along the length of the frames, in preferenceto the width, for better overall support.

The use of blocking or packing such as bricks, short pieces of lumber or scrap material either under scaffold baseplates or under mudsills is prohibited . Vibration can cause blocking to move or shift, and leave a scaffold legunsupported. Under such conditions, the scaffold can topple when heavy loads are applied.

Take particular care when erecting scaffolds on frozen ground. Thawing soil is often water-soaked, resulting inconsiderable loss of soil bearing capacity. Thawing is an important consideration where tarps or other covers will beplaced around a scaffold and the enclosed area is to be heated.



D. SCAFFOLD ERECTION AND BRACING

Fittings and Accessories

It is absolutely essential to install all the parts, fittings and accessories required for a scaffold, so that it is erected inaccordance with manufacturers’ instructions. If parts are not available at the site, make sure that they are obtained assoon as possible. Do not attempt to erect a scaffold with only a partial supply of base plates, braces, connectors, etc.Ensure that all the components are in good condition and examine them to see that they are not damaged. All fittingsmust be positive and securely connected.

Base Plates and Screw Jacks

Base plates must be used on all non-mobile scaffolding of a size and capacity as specified by the manufacturer.Combination base plates with screwjacks must not be over-extended. A good rule of thumb is to use the 2:1 ratio, theoutside (visible) length of exposed screw can only be a maximum of twice the inside screw length. (For example, a 24inch long screw jack can only have 16 inches of exposed screw and 8 inches of inside length. Consult the manufacturerfor complete design information on the particular screw jack.)

Plumbness

It is absolutely essential that the scaffold is erected plumb, to ensure maximum structural capability of the system.When the first tier of scaffold is erected, check for plumbness and continue doing so as the scaffold is built. Wherenecessary, adjustments can be made by using the adjustable screw jacks on the base plates. Settlement or slightvariations in the fit of the components may require additional adjustments as tiers are added to the scaffold tower. Thescaffold frame should be checked for plumbness after each tier is added to the scaffold. CSA Standard S269.2-M87specifies the following criteria for plumbness:



Maximum Variation from Plumb Maximum Height of Scaffold1/2 "( 12mm ) 10 ' ( 3m )3/4 " ( 19mm ) 20 ' ( 6m )1 1/2 " ( 38mm ) Maximum Height

In addition to the scaffold being plumb, each working deck must belevel.

Bracing

Bracing helps keep the scaffold frame plumb and square in both vertical and horizontal planes. Once frames have beenfitted with adjustable base plates, the braces must then be attached for each tower span. The braces should slide intoplace easily. If force is required, either the braces are bent or damaged or the frames are out of plumb or square. Bracesshould be secured at each end and the self-locking devices are moving freely and have fallen into place. Rust or slightdamage can prevent some of these devices from working properly, so it is essential to maintain the components inproper working condition.

Bracing in the vertical plane is a must on both sides of every frame. Bracing in the horizontal plane should be providedat the joint of every third tier of frames. Horizontal bracing should coincide with the point at which scaffold is tied tothe building or structure being worked on. Although it is sometimes omitted, horizontal bracing is necessary to maintainscaffold stability and full load-carrying capacity. The use of horizontal bracing on the first tier helps to square up thescaffold before nailing base plates to mudsills.

Bracing must be adequately secured in place. Otherwise, scaffold movement can dislodge the brace, reducing thestability of the scaffold. These devices must operate freely for ease of erection and dismantling. Trying to release ajammed or rusted drop hook when dismantling a scaffold has resulted in falls.

A brace which does not easily drop onto pins is an indicator that something is wrong. Itmay be that the brace is bent andmust be discarded. Often, however, it means the scaffold is twisted and out of plumb. Braces should not be forced orhammered onto the pin. The condition causing this difficulty must be corrected so that the brace slides onto the pineasily. Adjusting screw jacks slightly will often solve this problem. However, make sure that the scaffold is notadjusted out of plumb to make a brace fit.

Coupling Devices

Every scaffold manufacturer provides coupling devices to join scaffold frames together in the vertical plane. Thesedevices are sometimes omitted, with the belief that the bearing weight of the scaffold and its load will keep the frameabove firmly resting on the frame below. This will probably hold true until the scaffold moves or sways. Then the jointmay pull apart causing a scaffold collapse. Therefore, coupling devices must always be used and installed properly onevery leg of the scaffold at every joint as assembly proceeds.

Wheels or Castors

If wheels or castors are used, they must be securely attached to the scaffold and equipped with brakes. Failure toproperly attach wheels or castors to the frame has been the cause of many accidents involving rolling scaffolds. Ensurethat the ground is level and free of potholes and other obstructions. Wheels or castors must have brakes which are wellmaintained and easily applied.

Platform Erection

All parts and fittings must be in place and secure before platform components are placed on a scaffold tier. Whenproceeding with the next tier, workers should lift platform sections or planks from the previous tier leaving either oneplatform section or two planks. While this requires more material, it speeds up erection because workers have platforms



to stand on when erecting or dismantling the platform above.

Hoisting Materials

Where scaffolds will be more than three frames high, a suitable mechanical device will make the hoisting of materialseasier during erection. While materials can be pulled up by rope , it is easier to rig a pulley system to the scaffold sothat hoisting can be done by workers on the ground. This is much safer and eliminates the risk or workers falling fromthe scaffold platform as they pull materials up by rope. Ensure that you do not lift material in excess of the loadcapacity of the hoist system or the scaffold connection.

Dismantling

The dismantling of a scaffold proceeds in reverse order to its erection. Each tier should be completely dismantled andthe material lowered to the ground before dismantling of the next tier begins. If platform sections or planks have beenleft at each level during erection, it is best to lower additional platform materials from above to the working deck beingdismantled. Extra platform material can be lowered to the ground. Using this procedure, workers will be operating mostof the time from a fully decked in platform. In addition to this, workers should be equipped with a safety harness andlifeline for securement to a suitable anchoring system, since guardrails will not always be in place as dismantlingproceeds.

Removing jammed or rusted scaffold components can be a very hazardous operation. When scaffolds have been in thesame location for a long time, pins and other components may rust, braces become bent and materials such as mortar orpaint often build up on the scaffold parts. All of these can prevent components from separating easily. Tugging orpulling on stuck components can cause loss of balance leading to a fall. Workers should wear a safety harness andlanyard tied off to a secure anchor before attempting to loosen stuck or jammed parts. Do not hammer or pry apart thescaffold components. This may cause damage to the components and/or affect the structural integrity of the scaffoldmembers.

E. SCAFFOLD ACCESS

Fall Protection

In most cases, a proper system of fall protection can be instituted for workers erecting and dismantling scaffolding.Often the scaffold is being erected on the side of a building or structure. In this case, a lifeline can be secured to asuitable anchor on the building and a fall arrestor (rope grab) attachment to a full body harness will protect the worker



erecting the scaffolding.

Ladders

Whether built into scaffold frames, attached as a separate component or portable, ladders are an important means ofaccess to scaffold platforms. Falls connected with climbing up and down scaffolds would be substantially reduced ifadequate and properly erected ladders were always used.

There are four primary means of ladder access to a scaffold:

Climbing frames

Only scaffold frames having built-in ladders, as designed by the manufacturer for worker access, may be utilized. Amajor problem with ladders built into the frame is that planks sometimes stick out so far that it’s difficult to get fromthe ladder to the platform. This situation can be improved by using manufactured platform components which do notproject beyond the end support, or using a properly secured portable ladder.

Portable ladders

Portable extension ladders may be used on the inside of frames or on the exterior of the scaffold, but they must besecured at the top and bottom. The ladder must be set-up in accordance with standard safe ladder practice.

Stand-off vertical ladders

A stand-off vertical ladders is also an acceptable means to access scaffolding, but should also be restricted to 5 metres(16.5 ft) in height, unless a proper ladder climbing fall protection system is provided.

Scaffold stairway systems

The best method for scaffold access is a stairway built into the scaffold structure. This provides for complete fallprotection and also has built-in rest platforms. Rest platforms should be built so that the material cannot fall from onelanding to the next.

Points to Remember:

Ladder rails should extend at least 1 metre above the platform level to facilitate getting on and off. Stepping on andstepping off the ladder at the platform level with no handrails can be dangerous.

Where scaffold frames are not equipped with ladder rungs, ladders must be installed as the erection of each tierproceeds.

Rest stations should be decked in on scaffold towers at intervals no greater than every 5 metres (16.5 ft). Climbing isstrenuous work and accidents happen more frequently when climbers suffer from overexertion.

Ladders and Climbing

The ladder must be properly erected with rails projecting 1 metre (3.3 ft) above the platform of the scaffold. Debris,extension cords and tools should be cleared away from areas around the top and bottom of ladders. Both hands must befree to hold guardrails or ladder rails. Do not carry tools or materials by hand when climbing ladders. Wear a tool beltand pouch and move material up or down by rope. Three-point contact should always be used when climbing ladders.This means using two hands and one foot or two feet and one hand to maintain contact with the ladder at all times.Always face the ladder when climbing and always keep your center of gravity between the ladder rails.

F. WORK PLATFORMS

The choice of a scaffold platform depends on the type of work being performed and the task being undertaken. Before a



platform material is selected, an assessment must be made of the weight of workers, tools and materials to be supportedby the decking.

Typical Loads and Requirements

Work platforms shall only be located on the top and bottom of end frames, not across intermediate braces. A standardminimum platform capacity is a uniformly distributed load of 50 lbs/sq ft for construction related work. This is usuallysufficient for workers, their tools and equipment, and a moderate amount of light materials. (For example, two nominal50 mm x 250 mm (2" x 10") SPF planks spanning 2.1 metres (7 ft) would have an estimated total capacity of about 600pounds, enough for 2 workers and their tools).

This is insufficient for heavily loaded scaffolds such as those used for masonry construction. For masonry constructionwhere large pallets of concrete blocks are to be carried, minimum capacity should be at least a uniformly distributedload of

150 lbs/sq ft. This means that scaffolds with spans of 2.1 metres (7 ft) should be at least double-planked.Aluminum/plywood platforms should also have a layer of scaffold planks on top.

Aluminum/Plywood Platform Panels

These platforms are combination wood and aluminum pre-manufactured decking, with special fastening hardware. Theload-carrying capacity of these platforms has been determined by the manufacturer and should be marked on theplatform. It may vary form one manufacturer to the other. The platform capacity should be verified before usage andworkers notified as to the capacity.

The advantage of aluminum/plywood platform panels is that the decking can be easily replaced if damaged. Onedisadvantage is that the hooks on most models are subject to damage if dropped from the scaffold accidently duringdismantling.

Platform hooks and fastening hardware must be checked regularly for looseness, cracking and distortion. Damage canoccur if the platforms are dropped or thrown around carelessly. When used outdoors, these platforms should be securedto the scaffold frames. Otherwise, when left unloaded, they can be blown off the scaffold by strong winds.

Laminated Veneer Lumber

This material is a special type of exterior plywood rated by the manufacturer for scaffold use. The material ismanufactured in large sheets of various thicknesses which can be sawn to the sizes required for different uses. Thestrength varies from manufacturer to manufacturer, depending on method of fabrication and species of wood used.Users of the material should ask suppliers to furnish rated working loads for the scaffold spans on which the lumberwill be used.

In general, the material will be stronger than sawn lumber scaffold planks of similar size and species. The strength isalso more uniform than sawn lumber. Like all lumber and plywood, laminated veneer lumber is subject to deteriorationfrom weathering and rot. The planks must therefore be inspected routinely. Planks showing de-lamination, fungi orblisters should be removed from service.

Sawn Lumber Planks

Sawn lumber planks 50 mm x 250 mm (2" x 10") or larger have been the standard scaffold platform material for manyyears. They are readily available and the least expensive of the common platform materials. Planks must meet or exceedthe requirements for No.1 construction grade of the species group used, which should be either spruce-pine-fir (SPF) orDouglas fir. Although the SPF group has less strength, it is usually lighter and therefore easier to handle than Douglasfir.

A minimum of two, 50 mm x 250 mm (2" x 10") scaffold planks are required on all working levels, unless it is a



masonry scaffold, which requires a minimum width of 1.5 metres (or six 2" x 10" planks).

Scaffold planks must be cleated or other wise secured to prevent lateral movement. If there is a possibility of an upwardforce on the planks (i.e. wind load), then the planks must be secured against movement.

Since wood planks deteriorate they must be inspected on a regular basis and removed from service if inadequate. Thejump test, commonly known as the "gorilla test", is NOT recommended. Such methods cause undetectable damage tothe planks due to overstressing.

S awn Lumber Plank Inspection Criteria:

Scaffold planks must be examined prior to use on a scaffold and at regular intervals to ensure that the planks remain insafe condition.

1. Planks - The wood plank must be No. 1 construction grade lumber (S-P-F) Spruce-Pine-Fir, or better, nominal size50 mm x 250 mm (2" x 10"). They must be properly seasoned and free from bow, crook, cup or twisted warp.

2. Splits - Planks with splits wider than 10 mm (3/8 ") or lengthwise splits closer than 75 mm (3 ") to the edge of theplank must be removed from service. When a lengthwise split in a plank exceeds 1/2 the length of the plank, then thatplank should also be removed from service.

NOTE: Plywood cleats should NOT be used along the length of the plank to keep planks from splitting. It has beenfound that the cleats may cause the plank to rot beneath where the cleat has been fastened, due to moistureaccumulation and retention. Scaffold planks with cleats should be inspected immediately and removed from service ifthere is any indication of wood rot.

Proper end cleats must still be used or prevent the plank from sliding off the scaffold frame.

3. Woodgrain - The grain is not to exceed a slope of 1 in 12 along the length of the plank.

4. Knots - Knots must be sound, tight, and spaced well apart. Maximum knot size for a 50 mm x 250 mm (2" x 10")plank is 50 mm (2 "). Knots on the edge of a plank must not be greater than 10 mm (3/8 ") width, or spiked across theentire width.

Scaffold planks can also be weakened by dry rot. This condition is not easily recognized in its early stages, especially ifthe exterior of the planks are weathered. Planks substantially infected with dry rot are usually lighter than normal andmust NOT be used.

G. GUARDRAILS

Failure to provide guardrails is one of the main reasons for falls from scaffold platforms. Manufacturers of standardscaffolds have guardrail components which can be attached to the scaffold frames. Where these are not available,guardrails can be constructed from lumber or tube-and-clamp components. In Manitoba, guardrails are required on allopen sides of scaffold platforms in excess of 2.5 m (8 ft) in height.

Guardrails must be constructed to resist a force of at least 200 lbs. (900 Newtons) applied anywhere on the guardrail. Ifguardrails are composed of sawn lumber, the vertical members, top rail and mid-rail are to be made of 50 mm x 100mm (2" x 4") lumber and the toeboard should be 25 mm x 150 mm (1" x 6"). The lumber used should be Number 1construction grade SPF or better. The vertical wooden posts may be attached to the frame legs using U-clips or at leastfour "wraps" of No. 9 gauge wire with ends adequately twisted and secured.

Vertical cross-bracing is not considered to be a guardrail and must not be used in such a manner.

Tube-and-clamp guardrails may be constructed from standard aluminum scaffold tubing using parallel clamps to attachthe vertical posts to each frame leg. Top rails and mid-rails should also be attached to the vertical posts.



Most manufacturers have toeboard clips to quickly and easily fasten toeboards to standard tubular posts on eitherframes or guardrail posts.

Guardrails Missing or Removed

There may be situations where scaffolds are not yet equipped or have had the guardrail removed. If the scaffold is morethan one frame or tier in height (in excess of 2.5 m or 8 feet), personnel on the platform must tie-off with a safetyharness and lanyard to a secure anchor.

Midrails and Toeboards

A midrail should be provided where necessary, especially if workers are kneeling or bending over often to do work. Themidrail should have the same design capacity as the top rail.

Toeboards should be provided where there is a possibility of materials falling from the working level to a site below.The toeboard must be a minimum of 125 mm (5 ") in height.

H. SCAFFOLD STABILITY

Three-to-One Rule

The ratio of unsupported height to least lateral dimension on a scaffold should not exceed 3 to 1, unless the scaffold is:

1. tied-back to the structure at proper horizontal and vertical intervals

2. equipped with outrigger stabilizers to maintain the ratio of 3 to 1

3. equipped with a properly designed anchored guy wire system.

The 3-to-1 rule applies only to the extent that outriggers are extended symmetrically about the scaffold tower. If theoutriggers are extended only on one side toppling is prevented only in that direction. Similarly, toppling is prevented onthe opposite side only to the degree that the outriggers are extended. For situations like this which often occur in suchoperations as metal siding application, the 3-to-1 rule cannot be applied unless the scaffold is prevented from topplingto the side on which the outriggers are not fully extended. This means the scaffold must be erected against a structure orwall where the girts prevent the scaffold from toppling toward the building.

Outrigger Stabilizers

To maintain the 3 to 1 ratio, some scaffolds have outrigger stabilizers which may be attached to the scaffold base. Withdevices of this type, ensure that the outrigger is adjusted so that the foot will not be moved by vibration or dynamicloads on the platforms. Where stabilizers are used with castors, the castors must rest firmly on a solid surface with thestabilizer secured in the extended position before workers use the platform.

Tie-Back Requirements

Scaffolds which exceed the 3-to-1 rule must be tied in to a building or structure at intervals not exceeding 3 times theleast lateral dimension of the scaffold. This usually means tie-ins are applied at every third frame vertically and everysecond frame horizontally for tubular frame scaffolds. Tie-ins for tube-and-clamp scaffolds should be applied at everysecond node vertically and every third standard horizontally. These tie-ins must be capable of sustaining lateral loads inboth tension (pull) and compression (push).

There are a number of different tie-back methods, depending on the type and configuration of the supporting structureor building. These include anchor ties, reveal ties, box ties, through ties and others. In all cases, the system must becapable of supporting significant horizontal live and dead loads.



Tying-in with a couple of loops of #9 wire provides some support in tension but does not support a compressive load.While compression forces may only cause the scaffold to strike the building or structure, the movement may besufficient to knock a worker off the platform. Tie-ins must be capable of withstanding both tension and compressionforces and must have a positive securement at both the building face and scaffold frame.

It is not sufficient to use #9 wire tightened against a 50 mm x 100 mm (2" x 4") strut held against the structure, withouta positive securement system. There must be a positive means of anchoring the strut to the building or structure.

The tie-in systems must be designed by a professional engineer where open scaffold heights exceed 15 metres (50 feet)and hoarded scaffolds exceed 7.5 metres (25 feet). Wire is not to be used in a tie-back system for securing scaffoldingto a building or other structure, where the height of the scaffolding is greater than 15 m (50 ft.) . The tie-backs mustsustain anticipated wind loads or dynamic loads caused by work being done on the scaffold. Tie-in design loads must beincreased where heavy loads will be placed on the scaffold such as pallets of masonry materials. Hoarding increases thenumber of tie-backs to the building structure.

Hoarding/Tarps

Wind loads on a scaffold are another concern that affects tie-backs and bracing. These loads vary not only with speedbut with the height and shape of structures where the scaffold is located and the exposure of the location. In addition,scaffolds which are going to be enclosed (hoarded) for winter construction or sandblasting will be subjected tosignificantly larger wind loads. An engineer must be consulted for the design and erection of all hoarded scaffoldinggreater than 7.5 m (25 ft.) in height.

Where scaffolding is completely hoarded, adequate ventilation must be provided to ensure worker protection whenheating, sandblasting or other processes or procedures expose the worker to hazardous materials or agents.

Wind Uplift

Wind can lift lighter platform materials from the scaffold if they are not secured. Where severe wind conditions areanticipated or where high scaffolds are involved, platform materials such as aluminum/plywood panels should besecured to the scaffold. With some types of platform panels this may be done with wire or nails. Other pre-manufactured systems incorporate a sliding type locking device.

I. USE AND MAINTENANCE

Scaffold Location



Checking the scaffold location thoroughly beforehand will eliminate many of the problems that develop duringconstruction and will allow erection to proceed smoothly, efficiently and safely.

Before erecting a scaffold, check the location for:

1. ground conditions 2. overhead electrical wires 3. obstructions 4. variation in surface elevation 5. tie-in locations and methods 6. potential wind loading conditions

Overloading

Overloading scaffold platforms is one of the most frequent violations of good scaffold practice. Placing full pallets ofbricks or concrete blocks on a single layer of 50 mm x 250 mm (2" X 10") scaffold planks is, in most cases, overloadingthe platform. Double planking on decks may be necessary where pallets of masonry materials are to be supported.Wherever possible, the pallets should be placed over the frame supports. In addition, planks used to support masonrymaterials should be inspected for damage or deterioration regularly .

Overloading may affect stability as well as load-carrying capacity. Differential settlement is often a problem whereheavy loads are applied to scaffolds resting on uncompacted soils. A scaffold tower 9 metres (30 ft) high which settles25 mm (1 ") on one side can move 150 mm (6 ") at the top. Settlement puts stress on braces, tie-ins and frame joints.Heavy loads should be placed symmetrically on the platform to ensure that soil settlement is uniform.

Finally, the scaffold structure must be capable of carrying the loads to be applied. Both light-duty and heavy-dutyframes are available on the market. Light-duty frames should not be used where heavy loads will be involved. If theload-carrying capacity of the frames is not known, consult the manufacturer or supplier and obtain the load capacity ofthe scaffold frame system. The load-carrying capacity of frames usually varies with the height of the towers.

Rolling Scaffolds

Rolling scaffolds, other than those which are lifted off the ground on outriggers, must have brakes on all wheels. Allbrakes must be applied when the scaffold reaches the desired position. Scaffolds over one frame in height must not bemoved while a worker is on the platform. If for some reason workers must remain on the platform when the scaffold isbeing moved, they should be tied off to an independent structure with a fall arrest system. The floor area where thescaffold is to be moved should be free of bumps or depressions and cleared of all debris. Rolling scaffolds must besecurely pinned together and should always be fitted with horizontal bracing as recommended by the manufacturer.Scaffolds which are not securely pinned together can separate if they drop into a hole or depression or run into anobstacle at ground level. Horizontal bracing is necessary on a standard frame scaffold to keep it from folding upbecause the connections between frames and braces are essentially pinned joints.

Castors must be positively secured to the frame. Castors must be properly sized according to the manufacturersspecifications. A castor dropping off in a hole or depression in floors can cause serious accidents and injuries. Eachcastor should have a brake which is in good working order and can be easily applied and maintained. The castors orwheels should be suitable for the surface on which the scaffold is to be used. Small wheels are suitable for pavement orconcrete floors. Larger pneumatic wheels are necessary where soils are the working surface. Rolling scaffolds mustalways be used on a surface which is smooth, free of depressions and reasonably level.

Once again, workers should not be on a scaffold, when it is being moved.

Outriggers

Outriggers or stabilizers are used to provide base stability and maintain the 3-to-1 rule. They must be properly deployedand "snugged up" so that sufficient contact is made with the surface to prevent settlement or movement due to sidethrusts. On soil the outrigger feet should always be placed on a mudsill.

Housekeeping

Scaffold decks are usually small, narrow and confined. Tools and materials to be used should be stored in an orderlyfashion. Debris and waste materials should not be allowed to collect on the platform. It should be either put in acontainer or removed from the platform immediately. Waste pieces of lumber, pipe, wire and miscellaneous metal andsmall tools are tripping hazards which have caused many serious falls from scaffolds. Working safely on scaffoldsrequires keeping an orderly work area.

J. INSPECTION

Scaffold systems and components should be inspected before each use to ensure structural stability. Some main areas tocheck for include:

1. damage to frames, braces and other structural components 2. damage to hooks on manufactured platforms 3. splits, knots and dry rot in planks



4. de-lamination in laminated veneer lumber planks 5. compatibility of components 6. sufficient and proper components for the job 7. scaffolding that has been in place for long periods of time

Structural components that are bent, damaged or severely rusted should not be used. Similarly, platforms with damagedhooks should not be used. Planks showing damage should be discarded and removed from the site so that they cannotbe used for platform material.

Bracing Components

Most bracing systems for tubular frame scaffolds are manufactured from light materials and are easily damaged. Braceswith kinks, bends or deformation should NOT be used; such damage can significantly weaken them. The ends of bracesare frequently damaged by dropping them on concrete or other hard surfaces during dismantling. Ends of braces arealso frequently bent by forcing them onto the locking pin during erection. Constant bending can cause the ends to crack.Bracing ends should therefore be inspected before use and braces with cracked ends should be discarded. The scaffoldsupplier and/or Professional Engineer must certify the repair or replacement of any damaged components.



G L O S S A R Y

Definitions:

Mudsills - A minimum 50 mm x 250 mm (2" x 10") wood plank or other device used to support the scaffold frame baseplates or other support devices.

Base Plates - A device used to support and distribute the leg load of a scaffold system sized according to themanufacturer’s specification.

Outrigger Stabilizers - A device used to extend the support length at the base of the scaffolding in order to providestability against overturning.

Bracing - A system of members connecting frames or sections of scaffolding to make the scaffold structure and addstrength and rigidity between members.



Tie-Backs - A reinforcing connection device which secures a scaffold to a fixed structure.

Hoarding - A product or material draped over scaffolding to protect workers from wind, rain and cold.

Guardrail - A rail secured to uprights and erected along the exposed sides and ends of platforms. MR189/85 section22(1) stipulates that the minimum height of the guardrail shall be 900 mm (3 ft) and the maximum withoutincorporating a midrail be 1060 mm (3.5 ft). The guardrail should be wood or metal, but not a bracing component.

Platform - A working surface provided on a scaffold to support the weight of workers, tools and materials.

Planks - Refers to sawn lumber, 50 mm x 250 mm (2" x 10") or wider, used in creating scaffolding platforms. Alllumber dimensions are nominal.

Fall Arrest Systems - A fall protection system that prevents serious injury or death of a worker due to a fall, usuallyconsisting of a full body harness secured to a lanyard and lifeline.

Plumbness - Ensuring that the scaffold is balanced and erected at a 90 degree angle straight up from a level surface.

Coupling Devices - A connective device used to secure scaffold frames together.

Foundations - The surface upon which the scaffold is erected.

Toeboard - A barrier secured along the sides and ends of a platform to guard against the falling of materials or tools.

Engineering Design - The design of a scaffold system by a registered professional engineer, licensed to practiseEngineering in Manitoba. The sealed drawings of a scaffolding system should includes all appropriate information onloading capacities and, detailing on tie-backs, foundations, etc. These drawings must be kept on site.

(Back to the EWI Main Safety Page)

Find publications on Workplace Safety from Manitoba Canada

Documents

Guidelines for Access Scaffolding