What is the minimum distance that scaffolding platforms must extend beyond their supports?
Correct Answer
A) 6 inches
OSHA requires scaffold platforms to extend at least 6 inches but not more than 18 inches beyond their supports.
Why This Is the Correct Answer
OSHA 29 CFR 1926.451(b)(2) specifies that scaffold platforms must extend a minimum of 6 inches beyond their centerline of support. The standard also sets a maximum overhang of 18 inches (or 12 inches for planks thicker than 2 inches nominal) to prevent the plank from becoming a lever that could tip or dislodge under load. The 6-inch minimum ensures the plank is adequately supported and does not create a trip hazard from an abrupt edge.
Why the Other Options Are Wrong
Option B: 8 inches
8 inches is not the OSHA-specified minimum overhang for scaffold platforms. This option is close to the correct answer (6 inches) to create uncertainty, but OSHA's specific requirement is 6 inches minimum.
Option C: 4 inches
4 inches is below the OSHA minimum of 6 inches. A 4-inch overhang provides insufficient bearing surface and could allow the plank to shift or fall under worker loads.
Option D: 12 inches
12 inches is associated with the maximum overhang for planks exceeding 2 inches in nominal thickness under some conditions, not the minimum overhang. Confusing maximums with minimums is a common test trap.
Memory Technique
Remember '6 and 18' — scaffold planks must overhang at least 6 inches but no more than 18 inches. Think of a ruler: 6 inches is half a foot (the minimum to keep the plank stable), 18 inches is the maximum before it becomes a lever. '6 to 18, don't be late—stay within that scaffold plate.'
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