Scaffolding: General Requirements in Construction

A scaffold puts people to work at height on a temporary structure, with hazards of collapse, falls, falling objects, and power line contact. This standard sets the general rules for how a construction scaffold is designed, built, reached, used, and protected. Much of it rests on two people: a qualified person who designs the scaffold and a competent person who inspects it.

Who it applies to

The scaffold rules apply to all scaffolds used in workplaces covered by the construction standards (29 CFR Part 1926). They do not apply to crane or derrick suspended personnel platforms, and the criteria for aerial lifts are set out only in 1926.453 (1926.450(a)).

A competent person can identify existing and predictable hazards and has authorization to take prompt corrective measures to eliminate them (1926.450(b)). A qualified person has, by a recognized degree, certificate, or professional standing, or by extensive knowledge, training, and experience, successfully demonstrated the ability to solve problems related to the work (1926.450(b)).

What the standard requires

Capacity and design

• Each scaffold and scaffold component must be able to support, without failure, its own weight and at least 4 times the maximum intended load. The exceptions are paragraphs (a)(2) through (a)(5), which set different figures for certain suspension scaffold parts, and paragraph (g) on fall protection (1926.451(a)(1)).
• Scaffolds must be designed by a qualified person and constructed and loaded in accordance with that design (1926.451(a)(6)).

Platforms

• Each platform on all working levels must be fully planked or decked between the front uprights and the guardrail supports (1926.451(b)(1)). This does not apply to platforms used solely as walkways or solely by employees erecting or dismantling the scaffold. There, only the planking you establish is necessary for safe working conditions is required (Exception to 1926.451(b)(1)).
• Gaps between platform units, and between the platform and the uprights, must be no more than 1 inch wide, unless you can demonstrate that a wider space is necessary (1926.451(b)(1)(i)). Then the platform must be planked as fully as possible, and the open space between the platform and the uprights must not exceed 9 1/2 inches (1926.451(b)(1)(ii)).
• Each platform and walkway must be at least 18 inches wide (1926.451(b)(2)). Ladder jack, top plate bracket, roof bracket, and pump jack scaffolds must be at least 12 inches wide. Boatswains' chairs have no minimum width (1926.451(b)(2)(i)). A note to that paragraph says the 12 inch requirement for roof bracket scaffolds is stayed until November 25, 1997 or until rulemaking on the minimum width of roof bracket scaffolds has been completed, whichever is later (Note to 1926.451(b)(2)(i)). Where you can demonstrate an area is too narrow for 18 inches, platforms must be as wide as feasible and employees must be protected by guardrails and/or personal fall arrest systems (1926.451(b)(2)(ii)).

Supported scaffolds

• A supported scaffold with a height to base width (including outrigger supports, if used) ratio of more than 4 to 1 must be restrained from tipping by guying, tying, bracing, or equivalent means (1926.451(c)(1)).
• Poles, legs, posts, frames, and uprights must bear on base plates and mud sills or other adequate firm foundation (1926.451(c)(2)). Footings must be level, sound, rigid, and able to support the loaded scaffold without settling or displacement (1926.451(c)(2)(i)).
• Those same members must be plumb and braced to prevent swaying and displacement (1926.451(c)(3)).

Access

When a platform is more than 2 feet above or below a point of access, you must use a ladder, stair tower, ramp, walkway, or one of the other listed means. Crossbraces must not be used as access (1926.451(e)(1)).

Use

• A competent person must inspect scaffolds and components for visible defects before each work shift, and after any occurrence that could affect structural integrity (1926.451(f)(3)).
• Scaffolds must be erected, moved, dismantled, or altered only under the supervision and direction of a competent person qualified in that work, and only by experienced and trained employees selected by the competent person (1926.451(f)(7)).
• Scaffolds, and conductive material handled on them, must stay clear of exposed and energized power lines: 10 feet for uninsulated lines under 50 kV, 3 feet for insulated lines under 300 volts, and 10 feet for insulated lines from 300 volts to 50 kV. Above 50 kV, insulated or uninsulated, the distance is 10 feet plus 0.4 inches for each 1 kV over 50 kV. The table lists an alternative for those lines: 2 times the length of the line insulator, but never less than 10 feet (1926.451(f)(6)). You may work closer only where necessary for the work, and only after the utility or electrical system operator has been notified and has deenergized or relocated the lines or installed protective coverings (Exception to 1926.451(f)(6)).

Fall protection

• Each employee on a scaffold more than 10 feet above a lower level must be protected from falling to that level (1926.451(g)(1)). Certain scaffold types have their own rules. For all others, it is a personal fall arrest system or a guardrail system (1926.451(g)(1)(vii)).
• Guardrails must be installed along all open sides and ends of platforms, and before the scaffold is released for use by employees other than erection and dismantling crews (1926.451(g)(4)(i)).
• On supported scaffolds manufactured or placed in service after January 1, 2000, the top edge of the toprail must be between 38 and 45 inches above the platform surface. On supported scaffolds manufactured and placed in service before that date, and on all suspended scaffolds where both a guardrail and a personal fall arrest system are required, the range is 36 to 45 inches. When conditions warrant, the top edge may be higher than 45 inches if the guardrail system meets all the other criteria of paragraph (g)(4) (1926.451(g)(4)(ii)).
• Toprails must withstand a force of at least 200 pounds, or 100 pounds on single-point and two-point adjustable suspension scaffolds (1926.451(g)(4)(vii)).

Falling object protection

In addition to hardhats, each employee on a scaffold must have additional protection from falling hand tools, debris, and other small objects, through toeboards, screens, guardrail systems, debris nets, catch platforms, or canopy structures (1926.451(h)(1)).

Training

Each employee who works on a scaffold must be trained by a person qualified in the subject matter to recognize the hazards of the type of scaffold in use and to understand how to control them (1926.454(a)).

Each employee involved in erecting, disassembling, moving, operating, repairing, maintaining, or inspecting a scaffold must be trained by a competent person (1926.454(b)).

You must retrain when you have reason to believe an employee lacks the needed skill or understanding, including when worksite or equipment changes present a hazard the employee was not trained on (1926.454(c), (c)(1), (c)(2)).

Written programs and records

The paragraphs of 1926.451 and 1926.454 reviewed for this guide do not call for a written scaffold program, a written inspection record, or a training certificate.

Easy-to-miss requirements

• For employees erecting or dismantling supported scaffolds, a competent person must determine the feasibility and safety of providing fall protection. It is required where feasible and where it does not create a greater hazard (1926.451(g)(2)).
• Steel or plastic banding must not be used as a toprail or midrail (1926.451(g)(4)(xiii)).
• Employees must be prohibited from working on scaffolds covered with snow, ice, or other slippery material, except as necessary to remove it (1926.451(f)(8)).

Related guides

• Fall protection
• Ladders
• Electrical safety

Source

This guide is based on the text of 29 CFR 1926.451 as published on osha.gov. The regulation itself always controls. States that run their own OSHA-approved State Plans may have additional or stricter rules.