Whenever materials are dropped more than 20 feet to any point lying outside the exterior walls of the building, a(n) ___ is required.

When materials are dropped from a height greater than 20 feet to any point outside the exterior walls of a building, an enclosed chute is required primarily for safety reasons. This regulation is in place to prevent potential injuries from falling objects, which could pose a significant risk to workers and the public below. Enclosed chutes are designed to guide materials safely to the ground, minimizing the risk of accidents during the material handling process.

The necessity of using an enclosed chute aligns with safety standards, ensuring that materials are transported and disposed of in a controlled manner. Other alternatives, like a hand truck or dumpster, do not fulfill the same purpose since they do not provide the necessary vertical transport for dropping materials from a significant height. An elevator, while also capable of transporting materials, typically does not serve the function of safely discharging items onto the ground in a secure manner from a height, as it is designed for vertical movement within a building rather than dropping materials externally.