What is the weight per cubic foot of a modern high-rise building?

• A. 5 lbs
• B. 8 lbs
• C. 12 lbs
• D. 10 lbs

Answer: (B)

Estimating how much mass exists in a given volume helps firefighters assess how a building will perform under fire and during collapse scenarios. For a modern high-rise, the practical average density is about 8 pounds per cubic foot. This value balances the heavy components (steel, concrete, floors) with the large amount of empty space and finishes, giving a useful baseline when you don’t have exact structural data. It’s the figure most often used in fire service planning as a realistic, conservative approximation of a high-rise’s weight per volume.

Choosing a value like 5 pounds per cubic foot would understate the typical building mass, while 10 or 12 pounds per cubic foot would overstate it. The 8 pounds per cubic foot figure sits in the middle and reflects common practice for high-rise density estimates.