Which of the following are indicators a structure may be nearing collapse during a fire?

• A. Fresh paint and clean windows.
• B. Sagging floors, creaking or cracking sounds, spalling concrete, warped connections, and visible structural distress.
• C. No smoke and a cool interior.
• D. Active exterior firefighting only.

Answer: (B)

Recognize signs that the structural system is failing under heat. Sagging floors show the load paths are bending as materials lose strength, while creaking or cracking sounds indicate members are yielding and moving. Spalling concrete reveals the surface is breaking away as steel inside expands with heat, and warped connections point to joints losing alignment under high temperatures. Visible structural distress, such as cracks, buckling, or deformation, confirms the structure is no longer behaving normally and could collapse.

These signs together are a clear warning of imminent danger, which is why this option is the best indicator. Fresh paint and clean windows don’t reflect how the structure responds to fire, so they’re not reliable signs of impending collapse. No smoke and a cool interior suggests limited heat exposure so far and not an immediate collapse threat. Active exterior firefighting only indicates where operations are happening outside and doesn’t by itself prove interior collapse is imminent.