Which construction type is associated with the three-times-height collapse zone rule?

Which construction type is associated with the three-times-height collapse zone rule?

• A. Reinforced concrete walls
• B. Unreinforced masonry walls
• C. Wood frame walls
• D. Glass curtain walls

Answer: (B)

The idea behind the three-times-height collapse zone is that unreinforced masonry walls are highly vulnerable to catastrophic failure, sending heavy debris outward in unpredictable ways. Because the debris can travel a distance roughly three times the wall’s height, safety guidelines use a collapse zone extending about three times the wall height to keep people and equipment clear. This rule reflects the brittle, block-like failure of unreinforced masonry, where chunks can break loose and project far from the structure. Other construction types behave differently: reinforced concrete walls are tied with steel and tend to fail more gradually, wood frame walls have lighter, more variable debris patterns, and glass curtain walls shatter differently, so the three-times-height rule is specifically associated with unreinforced masonry. For a concrete sense, if a wall is 30 feet tall, the collapse zone would be around 90 feet out.

The idea behind the three-times-height collapse zone is that unreinforced masonry walls are highly vulnerable to catastrophic failure, sending heavy debris outward in unpredictable ways. Because the debris can travel a distance roughly three times the wall’s height, safety guidelines use a collapse zone extending about three times the wall height to keep people and equipment clear. This rule reflects the brittle, block-like failure of unreinforced masonry, where chunks can break loose and project far from the structure. Other construction types behave differently: reinforced concrete walls are tied with steel and tend to fail more gradually, wood frame walls have lighter, more variable debris patterns, and glass curtain walls shatter differently, so the three-times-height rule is specifically associated with unreinforced masonry. For a concrete sense, if a wall is 30 feet tall, the collapse zone would be around 90 feet out.