What is the safe collapse zone distance multiplier?

• A. 1 times building distance
• B. 1 1/4 times building distance
• C. 1 1/2 times building distance
• D. 2 times building distance

Answer: (C)

The safe collapse zone distance multiplier is about how far you should stay away from a building that may collapse. The multiplier used is 1.5 times the building’s height, so you should be at least one and a half times the vertical height away from the exterior. This extra margin accounts for debris that can be ejected outward and downward as the structure fails, as well as lean and unpredictable collapse patterns, giving crews space to move safely. Choosing 1.5x strikes a practical balance—smaller multipliers leave you at risk, while much larger ones aren’t typically necessary. To apply it, estimate the building height and multiply by 1.5 to set the collapse zone distance.