Labor & Industries (L&I), Washington State

Scaffolds Chapter 296-874, WAC

Effective Date: 10/06/07

WAC 296-874-400 Supported Scaffolds

For printing

YOUR RESPONSIBILITY:

To meet these requirements when using supported scaffolds

Make sure supported scaffolds and scaffold components meet strength requirements	WAC 296-874-40002
Prevent supported scaffolds from tipping	WAC 296-874-40004
Make sure supported scaffolds are properly supported	WAC 296-874-40006
Provide safe access for persons erecting or dismantling supported scaffolds	WAC 296-874-40008
Provide fall protection for persons erecting or dismantling supported scaffolds	WAC 296-874-40010
Meet these requirements when moving mobile scaffolds	WAC 296-874-40012
Meet these requirements when using bricklayers’ square scaffolds (squares)	WAC 296-874-40014
Meet these requirements when using fabricated frame scaffolds (tubular welded frame scaffolds)	WAC 296-874-40018
Meet these requirements when using integral prefabricated scaffold access frames	WAC 296-874-40020
Meet these requirements when using form scaffolds and carpenter’s bracket scaffolds	WAC 296-874-40022
Meet these requirements when using horse scaffolds	WAC 296-874-40024
Meet these requirements when using ladder jack scaffolds	WAC 296-874-40026
Meet these requirements when using outrigger scaffolds	WAC 296-874-40028
Meet these requirements when using pole scaffolds	WAC 296-874-40030
Meet these requirements when using pump jack scaffolds	WAC 296-874-40032
Meet these requirements when using repair bracket scaffolds	WAC 296-874-40034
Meet these requirements when using roof bracket scaffolds	WAC 296-874-40036
Meet these requirements when using step, platform, and trestle ladder scaffolds	WAC 296-874-40038
Meet these requirements when using tube and coupler scaffolds	WAC 296-874-40040
Meet these requirements when using window jack scaffolds	WAC 296-874-40042

 

WAC 296-874-40002

Make sure supported scaffolds and scaffold components meet strength requirements

You must

• Make sure each supported scaffold and scaffold component can support, without failure, the total of its own weight plus at least 4 times the maximum intended load applied or transmitted to it.

WAC 296-874-40004

Prevent supported scaffolds from tipping

You must

• Make sure supported scaffolds with a height to least base dimension ratio of greater than 4 to one are prevented from tipping by one or more of the following:
  • – Guying
  • – Tying
  • – Bracing
  • – Other equivalent means.

Note: The least base dimension includes outriggers, if used.

 

Guys, Ties, and Bracing

 

You must

• Install guys, ties, and braces where horizontal members support both the inner and outer legs of the scaffold.
• Install guys, ties, and braces:
  • - According to the scaffold manufacturer's recommendations
    or
  • - At all points where the following horizontal and vertical planes meet:
    • First vertical level at a height equal to 4 times the least base dimension
    • Subsequent vertical levels every:
      • – 20 feet (6.1 m) or less for scaffolds having a width of 3 feet (0.91 m) or less
      • – 26 feet (7.9 m) or less for scaffolds more than 3 feet (0.91 m) wide
    • Horizontally at:
      • – Each end of the scaffold
        and
      • – Intervals of 30 feet (9.1 m) or less.

Note: The 30-foot horizontal intervals are measured from one end of the scaffold to the other.

You must

• Make sure the highest level of guys, ties, or braces is no further from the top of the scaffold than a distance equal to 4 times the least base dimension.
• Make sure scaffolds that have an eccentric load applied or transmitted to them, such as a cantilevered work platform, are prevented from tipping by one or more of the following:
  • – Guying
  • – Tying
  • – Bracing
  • – Outriggers
  • – Other equivalent means.

WAC 296-874-40006

Make sure supported scaffolds are properly supported

You must

• Make sure supported scaffold poles, legs, posts, frames, and uprights are:
  • - Plumb
    and
  • - Braced to prevent swaying or displacement.
• Make sure supported scaffold poles, legs, posts, frames, and uprights, bear on base plates that rest on:
  • – Mudsills
  • or
  • – Other firm foundations such as concrete or dry, compacted soil.
• Make sure foundations are all of the following:
  • - Level
  • - Sound
  • - Rigid
  • - Capable of supporting the loaded scaffold without settling or displacement.

Note: The condition of the foundation may change due to weather or other factors. If changes occur, the foundation needs to be evaluated by a competent person to make sure it will safely support the scaffold.

• Make sure unstable objects aren't used:
  • - To support scaffolds or platform units
    or
  • - As working platforms.
• Make sure mobile scaffolds meet these additional requirements:
  • - Wheel and caster stems are pinned or otherwise secured in the scaffold legs or adjustment screws
  • – Wheels and casters are locked, or equivalent means are used, to prevent movement when the scaffold is being used
  • – Screw jacks or other equivalent means are used if it’s necessary to level the work platform.
• Make sure front-end loaders and similar equipment used to support scaffold platforms have been specifically designed for such use by the manufacturer.

Reference: When forklifts or other powered industrial trucks are used for personal lifting on support scaffold platforms, follow the requirements found in Forklifts and Other Powered Industrial Trucks, Chapter 296-863 WAC.

WAC 296-874-40008

Provide safe access for persons erecting or dismantling supported scaffolds

You must

• Provide a safe means of access for persons erecting or dismantling scaffolds if it is:
• - Feasible
  and
• - Does not create a greater hazard.
• Have a competent person determine the feasibility of providing safe access.
• Make sure the determination is based on site conditions and the type of scaffold being erected or dismantled.
• Install a hook-on or attachable ladder as soon as scaffold erection has progressed to a point where it can be safely installed and used.
• Make sure crossbraces on tubular welded frame scaffolds aren't used to access or egress from the scaffold.
• Make sure the frames of tubular welded frame scaffolds that are used as climbing devices meet all of the following:
  • - Create a usable ladder
  • - Provide good hand holds and foot space
  • - Have horizontal members that are all of the following:
    • Parallel
    • Level
    • Spaced not more than 22 inches apart vertically

WAC 296-874-40010

Provide fall protection for persons erecting or dismantling supported scaffolds

You must

• Have a competent person determine the feasibility of providing fall protection for persons erecting or dismantling supported scaffolds.
• Provide fall protection if the installation and use of fall protection is:
  • - Feasible
    and
  • - Does not create a greater hazard.

WAC 296-874-40012

Meet these requirements when moving mobile scaffolds

You must

• Make sure, before a scaffold is moved, that employees on the scaffold are made aware of the move.
• Apply manual force being used to move a scaffold:
  • - As close to the base as practicable
    and
  • -Within 5 feet (1.5 m) of the supporting surface.
• Make sure power systems used to propel mobile scaffolds have been designed for such use.
• Make sure forklifts, trucks, similar motor vehicles, or add-on motors aren't used to propel scaffolds unless the scaffold has been designed to be used with that type of propulsion system.
• Stabilize scaffolds to prevent tipping when they’re being moved.
• Make sure a scaffold isn't moved with employees riding on it unless all of the following are met:
  • - The surface on which the scaffold is being moved is:
    • Within 3 degrees of level
      and
    • Free of pits, holes, and obstructions
  • - No employee is on any part of the scaffold which extends out beyond the wheels, casters, or other supports
  • - Outrigger frames, when used, are installed on both sides of the scaffold
  • - The power system, if used:
    • Applies the propelling force directly to the wheels
      and
    • Produces a speed of one foot per second (.3 mps) or less
  • - The height of the scaffold:
    • Isn't more than 2 times the least base dimension
      or
    • The scaffold is designed and constructed to meet or exceed nationally recognized stability test requirements, such as those listed in ANSI/SIA A92.5, Boom-Supported Elevating Work Platforms, and ANSI/SIA A92.6, Self-Propelled Elevating Work Platforms.

WAC 296-874-40014

Meet these requirements when using bricklayers’ square scaffolds (squares)

You must

• Reinforce wood scaffolds with gussets on both sides of each corner.
• Make sure diagonal braces are installed:
  • - On all sides of each square
  • - Between squares on the front and back sides of the scaffold
  • - Extending from the bottom of each square to the top of the next square.
• Make sure scaffolds meet all of the following:
  • - Are no more than 3 tiers high
  • - Are constructed and arranged so that each square rests directly above another square
  • - The upper tiers:
    • Stand on a continuouos row of planks laid across the next lower tier
      and
    • Are nailed down or otherwise secured to prevent displacement.

WAC 296-874-40018

Meet these requirements when using fabricated frame scaffolds (tubular welded frame scaffolds)

You must

• Make sure scaffolds over 125 feet (38.0 m) high above their base plates are:
  • – Designed by a registered professional engineer
  • and
  • – Constructed and loaded as specified in the design.
• Brace frames and panels using crossbraces, horizontal braces, diagonal braces, or a combination thereof to secure vertical members together laterally.
• Make sure the length of the crossbraces will:
  • - Automatically square and align the vertical members
    and
  • - Make the scaffold plumb, level, and square.
• Secure all brace connections.
• Join frames and panels together vertically by using one of the following:
  • - Coupling pins
  • - Stacking pins
  • - Equivalent means.
• Use pins or other equivalent means to lock scaffold frames or panels together vertically where uplift may occur.
• Make sure brackets used to support cantilevered loads are all of the following:
  • - Seated with side-brackets parallel to the frames and end-brackets at 90 degrees to the frames
  • - Not bent or twisted from these positions
  • - Used only to support persons.

Exemption: Brackets may be used to support cantilevered loads other than personnel if the scaffold has been: - Designed for other loads by a qualified engineer and - Built to withstand the tipping forces caused by those loads.

You must

• Leave existing platforms undisturbed until new end frames have been set in place and braced, then move the platforms to the next level.

WAC 296-874-40020

Meet these requirements when using integral prefabricated scaffold access frames

You must

• Make sure integral prefabricated scaffold access frames meet all of the following:
  • – Have been specifically designed and constructed to be used as ladder rungs
  • – Have a rung length of at least 8 inches (20 cm)
  • – Have a maximum spacing between rungs of 16-3/4 inches (43 cm)
  • – Are uniformly spaced within each frame section
  • – Have rest platforms at least every 20 feet (6.1 m) on all supported scaffolds more than 24 feet (7.3 m) high.

Note: Non uniform rung spacing caused by joining end frames together is allowed, provided the resulting spacing doesn't exceed 16-3/4 inches (43 cm).

• Make sure, when panels with rungs that are less than 11-1/2 inches long are used as work platforms, that employees use either:
  • – A positioning device
  • or
  • – A personal fall arrest system.

Reference: For personal fall arrest system requirements in this chapter, go to WAC 296-874-20058. For construction activities, go to Fall Restraint and Fall Arrest, Part C-1, in Safety Standards for Construction Work, Chapter 296-155 WAC.

WAC 296-874-40022

Meet these requirements when using form scaffolds and carpenter’s bracket scaffolds

You must

• Secure folding-type metal brackets that have been extended for use, with:
  • - Bolts
    or
  • - Locking-type pins.
• Make sure wooden bracket-form scaffolds are an integral part of the form panel.
• Attach each bracket, other than those for wooden bracket-form scaffolds, to the supporting formwork or structure by using one or more of the following:
  • - Nails
  • - A metal stud attachment device
  • - Welding
  • - Hooking over a secured structural supporting member, with the form wales either:
    • Bolted to the form
      or
    • Secured by snap ties or tie bolts extending through the form and securely anchored
  • - For carpenters' bracket scaffolds only, using a bolt extending through to the opposite side of the structure's wall.

WAC 296-874-40024

Meet these requirements when using horse scaffolds

You must

• Make sure horse scaffolds aren't constructed or arranged higher than 2 tiers or 10 ft. (3.0 m), whichever is less.
• Do all of the following if horses are arranged in tiers:
  • - Place each horse directly over the horse in the tier below
  • - Nail down or otherwise secure the legs of each horse to prevent displacement
  • - Crossbrace each tier.

WAC 296-874-40026

Meet these requirements when using ladder jack scaffolds

You must

• Make sure platform height isn't higher than 20 feet (6.1 m).
• Make sure ladder jacks are designed and constructed so they rest:
  • - On the side rails and ladder rungs together
    or
  • - Only on the rungs.
• Make sure ladder jacks that rest on rungs only have a bearing area that includes a length of at least 10 inches (25.4 cm) on each rung.
• Make sure ladders used to support ladder jacks are:
  • - Type I (250 lbs. rated capacity) or Type IA (300 lbs. rated capacity)
    and
  • - Are placed, fastened, or equipped with devices to prevent slipping

Note: Ladders with a duty rating or weight capacity greater than a Type I ladder (250 lbs.) satisfy the requirement to use Type I or IA ladder.

• Make sure job-made ladders aren't used to support ladder jack scaffolds.
• Make sure scaffold platforms aren't bridged together.

Reference: There are specific fall protection requirements for employees using ladder jack scaffolds. Go to WAC 296-874-20056. Requirements for portable and fixed ladders are found in chapter 296-876 WAC, Ladders, portable and fixed.

WAC 296-874-40028

Meet these requirements when using outrigger scaffolds

You must

• Make sure outrigger scaffolds and scaffold components are:
  • - Designed by a registered professional engineer
    and
  • - Constructed and loaded as specified in the design.
• Make sure the part of the outrigger beam from the fulcrum point to the inboard end (farthest point of anchorage) is at least 1-1/2 times longer than the part from fulcrum point to the outboard end (the platform side).
• Place I-beam or channel shaped outrigger beams so that the web section is vertical.
• Make sure the fulcrum point of outrigger beams rests on secure bearings at least 6 inches (15.2 cm) in each horizontal dimension.
• Make sure outrigger beams are:
  • – Secured in place to prevent movement
    and
  • - Securely braced at the fulcrum point against tipping.
• Securely anchor the inboard ends of outrigger beams by using one or both of the following:
• – Braced struts bearing against sills that are in contact with the overhead beams or ceiling
  or
• – Tension members secured to the floor joists below.
• Securely brace the entire supporting structure to prevent any horizontal movement.
• Nail, bolt, or otherwise secure platform units to the outriggers to prevent platform displacement. Platform units must extend to within 3 inches of the building wall.

WAC 296-874-40030

Meet these requirements when using pole scaffolds

You must

• Make sure pole scaffolds over 60 feet high are:
  • – Designed by a registered professional engineer
    and
  • – Constructed and loaded as specified in the design.
• Leave existing platforms undisturbed until new bearers have been set in place and braced before moving the platforms to the new level.
• Install bracing on double-pole scaffolds as follows:
  • – Crossbracing between the inner and outer sets of poles
  • – Diagonal bracing in both directions across the entire outside face of the scaffold
  • – Diagonal bracing in both directions across the entire inside face of scaffolds that are used to support loads equivalent to a uniformly distributed load of 50 lbs. (222 kg) or more per square foot (929 sq. cm).
• Install diagonal bracing on single pole scaffolds in both directions across the entire outside face of the scaffold.
• Make sure runners meet all of the following:
  • – Are installed on edge
  • – Extend over a minimum of 2 poles
  • – Are supported by bearing blocks securely attached to the poles.
• Make sure bearers are:
  • – Installed on edge
    and
  • – Extend a minimum of 3 inches (7.6 cm) over the outside edges of runners.
• Make sure runners, bearers, and braces aren't spliced between poles.
• Make sure wood poles that are spliced together meet both of the following:
  • – The ends of the poles at the splice:
    • Are square
      and
    • The upper section rests squarely on the lower section
  • – Wood splice plates are provided that meet all of the following:
    • Are installed on at least 2 adjacent sides
    • Extend at least 2 feet (0.6 m) on either side of the splice
    • Overlap the abutted ends equally
    • Have the same cross-sectional areas as the pole.

Note: Splice plates of material other than wood may be used if they are of equivalent strength.

WAC 296-874-40032

Meet these requirements when using pump jack scaffolds

You must

• Make sure pump jack brackets, braces, and accessories are made from metal plates and angles.
• Make sure pump jack brackets have 2 positive gripping mechanisms to prevent any failure or slippage.
• Secure poles to the structure using rigid triangular bracing or the equivalent located at all of the following:
  • – Top
  • – Bottom
  • – Other points on the pole as necessary.
• Do both of the following when the pump jack has to pass bracing that’s already installed:
  • - Install an additional brace approximately 4 feet (1.2 m) above the brace to be passed
  • - Leave it in place until:
    • The pump jack has been moved
      and
    • The original brace is reinstalled
• Make sure work benches aren't used as scaffold platforms.

Note: A work bench may be used as a toprail only if it meets the toprail requirements in, Make sure guardrail systems meet these requirements, WAC 296-874-20064.

You must

• Make sure wood poles used with pump jack scaffolds are:
  • – Straight grained
  • and
  • – Free of shakes, large loose or dead knots, and other defects which might impair strength.
• Make sure wood poles that are constructed of 2 continuous lengths are joined together with the seam parallel to the bracket.
• Install a mending plate at all splices to develop the full strength of the member when splicing two-by-fours together to make a pole.

WAC 296-874-40034

Meet these requirements when using repair bracket scaffolds

You must

• Make sure brackets are all of the following:
  • – Secured in place by at least one wire rope that’s at least 1/2 inch (1.27 cm) in diameter
  • – Attached to the securing wire rope by a positive locking device, or equivalent, that will prevent the bracket from being unintentionally detached from the rope
  • – Provided with a shoe, heel block, foot, or a combination that:
    • Is located at the contact point between the supporting structure and the bottom of the bracket
      and
    • Will prevent lateral movement of the bracket
• Secure the platforms to the brackets in a way that prevents:
  • – The platforms from separating from the brackets
  • and
  • – The platforms or brackets from moving on a completed scaffold.
• Make sure wire rope placed around the structure to provide a safe anchorage for personal fall arrest systems used by employees erecting or dismantling scaffolds:
• – Is at least 5/16 inch (0.8 cm) in diameter
  and
• – Provides an anchorage that meets the requirements of WAC 296-874-20058.
  • For construction activities, go to Fall Restraint and Fall Arrest, Part C-1, in the Safety Standards for Construction Work, Chapter 296-155 WAC.
• Make sure each wire rope used for securing brackets in place or as an anchorage for personal fall arrest systems is all of the following:
• – Protected from damage due to contact with edges, corners, protrusions, or other parts of the supporting structure or scaffold components
• – Tensioned by a turnbuckle or equivalent means. Turnbuckles must be:
  • At least one inch (2.54 cm) in diameter
    and
  • Connected to the other end of its rope by an eye splice thimble that’s sized appropriate to the turnbuckle
• – Not used with U-bolt wire rope clips.

• Make sure materials aren't dropped to the outside of the supporting structure.
• Erect the scaffold by progressing around the structure in only one direction.

WAC 296-874-40036

Meet these requirements when using roof bracket scaffolds

You must

• Make sure scaffold brackets meet all of the following:
• – Are constructed to fit the pitch of the roof
• – Provide a level support for the platform
• – Are anchored in place by nails.

Note: If it’s not practical to use nails to anchor brackets, secure them in place with first grade manila rope of at least 3/4 inch (1.9 cm) diameter, or equivalent.

WAC 296-874-40038

Meet these requirements when using step, platform and trestle ladder scaffolds

You must

• Make sure ladders used to support step, platform, and trestle ladder scaffolds are:
• – Type I (250 lb. rated capacity) or Type IA (300 lb. rated capacity)
  and
• – Placed, fastened, or equipped with devices to prevent slipping.

Note: Ladders with a duty rating or weight capacity greater than a Type I ladder (250 lbs.) satisfy the requirements to use a Type I or Type IA ladder.

You must

• Make sure job-made ladders aren't used to support step, platform, and trestle ladder scaffolds.

Reference: There are specific fall protection requirements for employees using ladder jack scaffolds. Go to WAC 296-874-20056. Requirements for portable and fixed ladders are found in chapter 296-876 WAC, Ladders, portable and fixed.

 

You must

• Make sure scaffold platforms aren't placed higher than the second highest rung or step of the ladder supporting the platform.
• Make sure scaffold platforms aren't bridged together.

WAC 296-874-40040

Meet these requirements when using tube and coupler scaffolds

You must

• Make sure tube and coupler scaffolds over 125 feet high are:
• – Designed by a registered professional engineer
  and
• – Constructed and loaded as specified in the design.
• Leave existing platforms undisturbed until new bearers have been set in place and braced before moving the platforms to the new level.
• Install crossbracing across the width of the scaffold that meets all of the following:
• – Bracing is installed at:
  • Each end of the scaffold
    and
  • At least at every third set of posts horizontally and every fourth runner vertically.
• – Bracing extends diagonally from the:
  • Outer posts or runners upwards to the next inner posts or runners
    and
  • Inner posts or runners upwards to the next outer posts or runners.
• Install building ties:
• – At the bearer levels between the crossbracing
  and
• – At locations specified in WAC 296-874-40004.
• Install longitudinal bracing on straight run scaffolds as follows:
  • – Diagonally in both directions across the inner and outer rows of posts
  • – From the base of the end posts upward to the top of the scaffold at approximately a 45 degree angle
  • – As close as possible to the intersection of the bearer and post or runner and post
  • – If the scaffold is longer than it is tall, repeat the bracing beginning at every fifth post
  • – If the scaffold is taller that its length, install the bracing:
    • From the base of the end posts upward to the opposite end posts
      and
    • In alternating directions until reaching the top of the scaffold.
• Attach bracing to the runners as close to the post as possible, if bracing can’t be attached to the post.
• Make sure bearers meet all of the following:
  • – Are installed transversely between posts
  • – If the bearer is coupled to the post, have the inboard coupler bear directly on the runner coupler
  • – If the bearer is coupled to the runners, have the couplers as close to the posts as possible
  • – Extend bearers beyond the posts and runners
  • – Provide full contact with the coupler
  • – The bottom bearers are located as close to the base as possible.
• Make sure runners meet all of the following:
• – Are installed along the length of the scaffold
• – Are located on both the inside and outside posts at the same height
• – Are interlocked on straight runs to form continuous lengths and are coupled to each post
• – The bottom runners are located as close to the base as possible.

Note: Tube and coupler guardrails and midrails installed on outside posts can be used in lieu of outside runners.

You must

• Make sure couplers are made of a structural metal, such as drop-forged steel, malleable iron, or structural grade aluminum.

• Prohibit using couplers made of gray cast iron.

WAC 296-874-40042

Meet these requirements when using window jack scaffolds

You must

• Make sure window jack scaffolds meet all of the following:
• – Are securely attached to the window opening
• – Are used for working only at the window opening the jack is placed through
• – Aren't used:
  • To support planks placed between one window jack and another
    or
  • As any other element of scaffolding.