An enclosed chute of wood or similar material is REQUIRED whenever materials are dropped more than how many feet to any point lying outside the exterior walls of a building?

• A. 10 feet
• B. 15 feet
• C. 20 feet
• D. 30 feet

Answer: (C)

The main idea is safety containment: when materials could fall from height toward space outside the building, you need a protected path to keep debris from injuring people or damaging property. The rule sets a threshold at more than twenty feet. If the drop is greater than twenty feet, an enclosed chute made of wood or a similar material is required to contain the falling material and direct it away from pedestrians and other hazards. This reflects how risk increases with height, so the enclosure helps control the debris plume and reduces exposure to the public.

Dropping from twenty feet or less generally does not meet this specific requirement, so the enclosure is not mandated by this rule. The other numbers don’t define the trigger for this protection: ten or fifteen feet are below the threshold, and thirty feet would satisfy the condition but the stated rule is anchored at twenty feet as the cut-off.