Commercial Building Inspector B2Wall Construction and Wall CoveringsEasy
An inspector is evaluating a 1-hour fire-resistance-rated corridor wall in a commercial building. The wall contains a duct penetration. What is the minimum fire-resistance rating required for the fire damper protecting this penetration if the duct is not part of a hazardous exhaust system?
- A1.5 hours
- B1 hour
- C2 hours
- D0 hours (no damper required)
Show answer & explanationAnswer & explanation
Correct answer: B. 1 hour
For ducts penetrating a 1-hour fire-resistance-rated corridor wall, a minimum 1-hour fire damper is required, provided the duct is not part of a hazardous exhaust system or other specific exceptions.
Why the other options are wrong
- A. 1.5-hour dampers are generally for 2-hour rated partitions or specific shafts.
- C. 2-hour dampers are typically for ducts penetrating 3-hour or higher fire-rated assemblies.
- D. Dampers are required for duct penetrations through fire-rated walls.
Duct Penetration Fire Damper Rating
The minimum fire-resistance rating required for a fire damper protecting a duct penetration through a fire-resistance-rated wall.
- Damper rating typically matches the wall rating for 1-hour walls.
- Different rules apply for shaft enclosures and hazardous exhaust systems.
- Fire dampers prevent the spread of fire and smoke through ducts.
Memory trick: Damper's hour matches wall's power.