Special Use Supported Scaffolds
Special use scaffolds should be capable of supporting their own weight and at least four times the maximum intended load applied or transmitted to the scaffold and components.
Form and Carpenter Bracket Scaffolds
Form scaffold: A form scaffold is a supported scaffold consisting of a platform supported by brackets attached to a formwork.
Carpenter’s Bracket Scaffold: A carpenter’s bracket scaffold is a supported scaffold consisting of a platform supported by brackets attached to building or structural walls.
- Make sure each bracket, except those for wooden bracket-form scaffolds, is attached to the supporting framework or structure by one or more of the following:
- metal stud attachment device
- hooking over a secured structural supporting member, with the form walls either:
(for carpenters' bracket scaffolds only) by a bolt extending through to the opposite side of the structure's wall
- bolted to the form
- secured by snap ties or tie bolts extending through the form
- securely anchored
- Ensure wooden bracket-form scaffolds are an integral part of the form panel.
- Ensure folding-type metal brackets, when extended for use, are either bolted, or secured with a locking-type pin.
Roof Bracket Scaffolds
A roof bracket scaffold is a rooftop supported scaffold consisting of a platform supported by triangular shaped supports.
- Ensure brackets conform to the pitch of the roof and produce a level support for the platform.
- Check that brackets are secured in place by nails.
- When nails are not practical, make sure brackets are anchored by 3⁄4-inch first grade manila rope or its equivalent.
An outrigger scaffold is a supported scaffold consisting of a platform supported by outrigger beams (thrustouts) projecting beyond the wall or face of a building or structure with the inboard ends
secured inside the building or structure.
When inspecting Outrigger Scaffolds, check the following:
- Make sure outrigger beams are:
- secured in place to prevent movement
- securely braced at the fulcrum point to prevent tipping
- Make sure the inboard end of outrigger beams are:
- not less than 1½ times the length of the outboard end, measured from the fulcrum point to the extreme anchorage point
- securely anchored either by:
Check that the fulcrum point of outrigger beams rest on secure bearings at least 6 inches in each horizontal dimension.
If outrigger beams are fabricated in the shape of an I-beam or channel beam, make sure they are placed so that the web section is vertical.
Make sure the entire supporting structure is securely braced to prevent any horizontal movement.
To prevent their displacement, make sure platform units are:
- braced struts bearing against sills in contact with the overhead beams or ceiling
- tension members secured to the floor joists underfoot
- both braced struts or tension members
Verify scaffolds and scaffold components are:
- otherwise secured to outriggers
- designed by a registered professional engineer
- constructed and loaded in accordance with that design
Inspecting Pump Jack Scaffolds
A pump jack scaffold is a supported scaffold consisting of a platform supported by vertical poles and movable support brackets. When inspecting these scaffolds, check the following:
- Make sure brackets, braces and accessories for pump jack scaffolds are fabricated from metal plates and angles.
- Check that two positive gripping devices are being used for each bracket.
- Ensure poles are secured to structures by rigid triangular bracing or its equivalent at the bottom, top, and other points.
- Verify that when the platform is raised, crossbracing is added about 4 feet on the side opposite the pump jack brace and should be left in place until the pump jack has been moved and the
initial brace has been reinstalled.
- If wood poles are used, make sure the lumber is straight-grained, free of shakes and large loose or dead knots and other imperfections that may reduce the strength of the wood.
- If two consecutive lengths are used to form the wood poles, make sure the poles are connected together with the seam parallel to the bracket.
- If two-by-four lumber is used to create a pole, make sure the splices are strong enough to maintain the full strength of the member.
- Make sure workbenches are not used as scaffold platforms.
Ladder Jack Scaffolds
Personal fall arrest systems are required to protect workers on ladder-jack scaffolds. However, this one appears to be out of adjustment.
The lanyard’s attachment to the lifeline’s rope grab is too low, allowing this worker to free fall more than six feet and possibly contact the ground.
A ladder jack scaffold is a simple device consisting of a platform resting on brackets attached to a ladder. Ladder jacks are primarily used in light applications because of their portability
and cost effectiveness. When inspecting these platforms, check the following:
- Check that all ladders used to support ladder jack scaffolds comply with 1926 Subpart X - Stairways and Ladders.
- Make sure job-made ladders are NOT used to support ladder jack scaffolds.
- Verify ladder jacks are designed and constructed to bear on:
- the side rails and ladder rungs
- the ladder rungs alone
- If ladder jacks bear on the ladder rungs alone, check that the bearing area includes a length of at least 10 inches on each rung.
- Make sure ladders used to support ladder jack scaffolds are:
- placed to prevent slipping
- fastened to prevent slipping
- equipped with devices to prevent slipping
- Verify platforms are not being placed higher than 20 feet from the supported base. Make sure scaffold platforms are not being bridged together.
- Verify the intent is not to exceed the ladder jack scaffold load limit of 25 pounds per square inch.
- Verify not more than two employees are occupying any platform at one time.
- Check that the maximum span between supports is no more than 8 feet.
Inspecting Window Jack Scaffolds
A window jack scaffold is a supported scaffold consisting of a platform supported by a bracket or jack that projects through a window opening. When inspecting these scaffolds,
check for the following:
- Verify scaffolds are being securely attached to the window opening.
- Verify scaffolds are being used only for working at the window opening through which the jack is placed.
- Check to make sure window jacks are not being used to support planks or other elements of scaffolding placed between one window jack and another.
- Verify not more than one employee is allowed to work on the scaffold at any one time.
A horse scaffold means a supported scaffold consisting of a platform supported by construction horses.
- Make sure these scaffolds are no more than 10 feet or two tiers in height, whichever is less.
- When horses are arranged in tiers, make sure:
- Each horse must be placed directly over the horse in the tier below.
- The legs of each horse must be nailed down or otherwise secured to prevent displacement.
- Each tier must be crossbraced.
- Check construction of the scaffold to make sure it conforms to the guidelines in the table below.
|Maximum intended load (light duty)
|Maximum intended load (medium duty)
||50 pounds/foot 2*
|Bearers (light duty)
||2 x 4 inches
|Bearers (medium duty)
||3 x 4 inches
||2 x 4 inches
|Longitudinal bracing between legs
||1 x 6 inches
|Gusset braces at top of legs
||1 x 8 inches
|Half diagnonal braces
||2 x 4 inches
|*Horses shall be spaced not more than 8 feet apart for light-duty loads, and not more than 5 feet apart for medium-duty loads. [1926 Subpart L Appendix A (2)(f)]
Crawling Board (Chicken Ladder) Scaffolds
A crawling board (chicken ladder) is a supported scaffold consisting of a plank with cleats spaced and secured to provide footing for use on sloped surfaces such as roofs.
- Make sure the crawling boards extend from the roof peak to the eaves when used in roof construction, repair, or maintenance.
- Verify crawling boards are secured to the roof by:
- ridge hooks
- by means that provide equivalent strength and durability
- Check that crawling boards are no less than 10 inches wide and 1 inch thick.
- Check the cleats on crawling boards to make sure they:
- are equal in length to the width of the board
- are spaced at equal intervals not to exceed 24 inches
- have a minimum cross-sectional area of 1 x 1-1/2 inches
Step, Platform and Trestle Ladder Scaffolds
A step, platform and trestle ladder scaffold is a supported scaffold consisting of a platform supported directly on the rungs of step ladders or a building wall.
- Verify scaffold platforms are placed no higher than the second-highest rung or step of the ladder supporting the platform.
- Check that all ladders meet the requirements of 1926 Subpart X (Stairways and Ladders).
- Ensure ladders are prevented from slipping by how they are placed, fastened or equipped.
- Make sure job-made ladders are not permitted to be used for these scaffolds.
- Make sure these scaffolds must not be bridged one to another.
Inspecting Plasterers', Decorators', and Large-Area Scaffolds
Check these scaffolds to make sure they are constructed in accordance with the requirements for the following scaffolds, as appropriate:
- pole scaffolds
- tube and coupler scaffolds
- fabricated frame scaffolds
Note: The guidelines for pole scaffolds, or tube and coupler scaffolds, may be applied.
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