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: not 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 and source
worst 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.
OSHA 29 CFR 1926.451(b), Subpart L - Scaffolds. A US federal regulation in the public domain, quoted directly.
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