Ten-foot long planks used on scaffolding should not extend over the edges of the support by more than how many inches?

• A. 16 inches
• B. 18 inches
• C. 12 inches
• D. 10 inches

Answer: (C)

When placing a plank on scaffolding, the amount of overhang beyond the edge of the support is limited to prevent tipping or bending under load. For a ten-foot plank, the maximum safe overhang is twelve inches. Keeping the extension to 12 inches helps ensure enough of the plank is still supported on the end, reducing the risk that the plank will loosen, crack, or shift when someone is standing or moving on it. Extending more than that creates a longer lever and greater chance that the board will fail or slip off the support. A shorter overhang is safer, but twelve inches is the standard maximum for this setup.