How the scaffold standard is organised
OSHA's construction scaffold rules were rewritten in 1996 and have been stable since. They sit in 29 CFR Part 1926, Subpart L, and they are shorter than most people expect. Six sections and a handful of appendices:
| Section | What it covers |
|---|---|
| 1926.450 | Scope and definitions: competent person, qualified person, duty ratings, the scaffold types |
| 1926.451 | General requirements for every scaffold: capacity, platforms, supported and suspended scaffold criteria, access, use, fall protection, falling-object protection |
| 1926.452 | Additional requirements for specific types: pole, tube and coupler, frame, pump jack, ladder jack, swing stage, mobile and the rest |
| 1926.453 | Aerial lifts (boom and bucket trucks), which borrow ANSI A92 |
| 1926.454 | Training for users, erectors, dismantlers and inspectors |
| Appendices A–E | Non-mandatory guidance: plank grades and span tables, criteria for specific types, a list of national consensus standards, fall protection for erectors, drawings |
Almost every scaffold citation is written under 1926.451. If you learn one section, learn that one. The seven guides in this series each take a piece of it.
The numbers that come up on every job
Subpart L is a standard of specific quantities. These are the ones a competent person carries in their head; each links to the guide that explains it.
| Requirement | Figure | Where |
|---|---|---|
| Capacity safety factor | 4 times the maximum intended load (6 times for suspension ropes) | 1926.451(a) |
| Fall protection required above | 10 feet to a lower level | 1926.451(g)(1) |
| Top rail height | 38 to 45 inches above the platform | 1926.451(g)(4) |
| Toe board height | At least 3.5 inches | 1926.451(h)(4) |
| Minimum platform width | 18 inches (12 for ladder jack, pump jack, roof and top plate brackets) | 1926.451(b)(2) |
| Platform gap and distance from work | Gaps no more than 1 inch; front edge within 14 inches of the work (18 for plastering) | 1926.451(b)(1), (b)(3) |
| Plank overhang | At least 6 inches past the support; no more than 12 (18 on platforms over 10 ft) | 1926.451(b)(4), (b)(5) |
| Plank overlap | At least 12 inches over a support | 1926.451(b)(7) |
| Tie when taller than | 4 times the minimum base width; then every 20 ft vertically (26 if over 3 ft wide) and 30 ft horizontally | 1926.451(c)(1) |
| Access required above | 2 feet above or below the point of access | 1926.451(e)(1) |
| Power line clearance | 10 feet for lines up to 50 kV; 3 feet for insulated lines under 300 V | 1926.451(f)(6) |
| Inspection frequency | Before each work shift and after any occurrence that could affect the scaffold | 1926.451(f)(3) |
| Engineer required | Frame and tube-and-coupler scaffolds over 125 feet; pole scaffolds over 60 feet | 1926.452(a), (b), (c) |
| Mobile scaffold riding ratio | Height-to-base 2:1 or less, or outriggers both sides | 1926.452(w)(6) |
Who is responsible for what
Subpart L names three roles and gives each specific duties. On a small job one person may hold all three; on an industrial site they are usually three people from two or three employers.
- The competent person inspects the scaffold before each shift, supervises every erection, alteration and dismantling, selects and trains the erectors, decides whether fall protection is feasible for them, and has the authority to stop work. The training guide covers what the role requires.
- The qualified person designs the scaffold, or confirms that a standard configuration matches the manufacturer's load chart, and designs horizontal lifelines and any non-standard rigging.
- A registered professional engineer designs frame and tube-and-coupler scaffolds over 125 feet, pole scaffolds over 60 feet, and any scaffold that will be moved horizontally with workers on it.
Employers are responsible for training their own workers (1926.454) and for their protection on the scaffold. The controlling contractor is responsible for the scaffold as a site condition. The scaffold supplier is responsible for what it erects and hands over, and for the accuracy of its load charts. Where those lines fall on your job should be in the contract, because they are the first thing argued about after an incident.
State plans and local rules
Roughly half the states run their own OSHA-approved programs, and a state plan must be at least as effective as the federal standard but may be stricter. California, Washington, Oregon and Michigan, among others, have scaffold rules with their own numbering and some tighter requirements. Cities add another layer: New York City requires Department of Buildings scaffold training and permits well beyond federal OSHA, and several cities require permits for sidewalk sheds and swing stages.
This guide describes the federal standard. Where you work under a state plan, read that plan's scaffold section alongside it, and where you work in a large city, check the building department's requirements before the first delivery.
Using this guide
Each of the seven guides below stands alone. Start with inspection if you are the competent person walking a scaffold tomorrow morning, with fall protection if you are writing a site safety plan, and with training if you are staffing a crew. Every guide names the paragraph of Subpart L behind each requirement so you can check it against the current text on osha.gov, which is the only authoritative source.
When you need people rather than reading, the directory filters suppliers by the OSHA Compliant qualification and by scaffold training and certification services, and our consulting practice walks scaffolds and safety programs for contractors and owners.