Commercial Building Inspector B2Wall Construction and Wall CoveringsMedium
A commercial building inspector is evaluating the fire-stopping at a penetration through a 2-hour fire-resistance-rated concrete floor assembly. The penetration is for a noncombustible pipe with an annular space of 1 inch. What is the minimum fire-resistance rating required for the fire-stopping system?
- A3 hours
- B1 1/2 hours
- C1 hour
- D2 hours
Show answer & explanationAnswer & explanation
Correct answer: D. 2 hours
According to IBC 714.3.1.2, fire-stopping for through-penetrations in fire-resistance-rated assemblies must have an F-rating and a T-rating not less than the required fire-resistance rating of the assembly, but not less than 1 hour. Therefore, for a 2-hour assembly, a 2-hour rating is required.
Why the other options are wrong
- A. A 3-hour rating is typically required for higher-rated assemblies (e.g., 3-hour fire walls) or specific conditions, not a 2-hour floor.
- B. This rating is sometimes used for specific conditions, but not generally for a 2-hour floor assembly.
- C. This rating would be insufficient for a 2-hour fire-resistance-rated assembly.
Fire-Stopping Rating (Through-Penetrations)
Fire-stopping for through-penetrations in fire-resistance-rated assemblies must have an F-rating and a T-rating not less than the required fire-resistance rating of the assembly, with a minimum of 1 hour.
- Prevents fire and smoke spread through openings.
- F-rating for flame, T-rating for temperature rise.
- Rating must match or exceed the assembly rating.
Memory trick: Fire-stopping must seal the gaps, its rating matches the wall's traps.