Scaffold Per-Leg Load and OSHA 4:1 Check
The load on each scaffold leg and whether it clears the OSHA 4:1 safe working load.
Example
You enter
- Platform + scaffold dead load in the bay (lb) 100
- Workers on the bay (count) 2
- Weight per worker with tools (lb) 250
- Stored material load (lb) 500
- Legs sharing the bay (count) 4
- Manufacturer leg / frame rating (lb) 2500
You get
- Total load (lb) 1100
- Load per leg 275 lb (OK)
- Safe working load per leg 625 lb
- Utilization 0.44
Details, formula, and sources
total = platform dead + workers x 250 lb + material; leg load = total / legs; SWL = component rating / 4. A bay with two workers, 500 lb of material, and a 100 lb platform puts 275 lb on each of four legs - fine against a frame rated 2,500 lb, but load it heavier and it crosses the 4:1 line. Feeds the mudsill bearing check; a competent person verifies.
total_load_lb = platform_dead_lb + num_workers x worker_lb + material_lb; leg_load_lb = total_load_lb / n_legs; swl_lb = component_rating_lb / 4; pass = leg_load_lb <= swl_lb.
OSHA capacity rule by name (safe working load = rating / 4; leg load = total intended load / legs); first-principles load distribution.
The 4:1 rule and 250-lb-per-person basis are public OSHA requirements; the component rating comes from the manufacturer.
Estimate. AHJ and licensed professional govern.
Field names used by the API: platform_dead_lb, num_workers, worker_lb, material_lb, n_legs, component_rating_lb, total_load_lb, leg_load_lb, swl_lb, utilization
- Intended load platform/scaffold dead load + 250 lb per worker (with tools) + stored materialOSHA 1926.451(a)(1)
- Safe working load the manufacturer component rating divided by the OSHA 4:1 safety factor, shared evenly over the legsOSHA 1926.451(a)(1) / manufacturer