Scaffold Platform and Planking Check (OSHA 1926.451(b))
The deck the guardrail stands on, and the rule worth knowing is that the maximum overhang follows the BOARD, not the bay.
Example
You enter
- Platform or plank length (ft) 8
- Platform width (in) 19
- Gap between adjacent platform units (in) 0.75
- Gap between the platform and the uprights (in) 1.5
- Overhang past the support (in) 15
- Front edge to the face of the work (in) 12
- Cantilevered portion designed not to tip? no
- Front-edge guardrail and/or personal fall arrest? no
You get
- Worst gap (in) 1.5
- Max overhang (in) 12
- Overhang excess (in) 3
- Width (18 in min) OK
Checked against published worked examples from: Occupational Safety and Health Administration.
Details, formula, and sources
ScopeNot more than 12 in over its support for a platform 10 ft or less, and 18 in for one over 10 ft. So the identical 15 in overhang FAILS on an 8 ft plank and PASSES on a 16 ft one -- swapping a long plank for two short ones tightens the limit with nothing else changing. Both limits carry the same escape, a cantilever designed not to tip, so a long overhang is a design question rather than a prohibition. Gaps run TWO ways at 1 in each -- between adjacent units and between the platform and the UPRIGHTS, the second being the one people forget because it is against the frame rather than between boards, and exactly where a foot goes. Plus 18 in minimum width and the 14 in front edge with its guardrail/PFAS escape.
Formula or tableworst gap = max(gap between adjacent units, gap between platform and uprights), capped at 1 in; platform width >= 18 in; maximum overhang = 12 in where the platform length is 10 ft or less and 18 in where it is greater, satisfied either within the limit or by a designed non-tipping cantilever; front edge <= 14 in from the face of the work, satisfied either within the limit or by front-edge guardrails and/or personal fall arrest.
Source and editionOSHA 29 CFR 1926.451(b), Subpart L - Scaffolds. A US federal regulation in the public domain, quoted directly.
Free access29 CFR is published in full at no cost by OSHA and the eCFR.
What governsEstimate. AHJ and licensed professional govern.
API field namesplank_length_ft, platform_width_in, gap_between_units_in, gap_to_uprights_in, overhang_in, front_edge_gap_in, cantilever_designed, front_edge_protected, worst_gap_in, max_overhang_in, overhang_excess_in, width_deficit_in
- Gaps 1 in maximum between adjacent units AND between the platform and the uprights29 CFR 1926.451(b)(1)
- Width at least 18 in for each platform and walkway29 CFR 1926.451(b)(2)
- Front edge not more than 14 in from the face of the work, unless guardrails and/or PFAS29 CFR 1926.451(b)
- Overhang 12 in at 10 ft or less, 18 in over 10 ft - the limit follows the plank length29 CFR 1926.451(b)(5)
- Cantilever escape either limit is met by a design that supports the cantilever without tipping29 CFR 1926.451(b)(5)
- Minimum bearing the minimum extension over the support is real but unverified here and is NOT assertedstated scope limit