Commercial Building Inspector B2Wall Construction and Wall CoveringsMedium
An inspector is reviewing the plans for a retail building where a 1-hour fire-resistance-rated corridor wall is penetrated by a non-combustible duct. What is the minimum fire-resistance rating required for the fire damper installed in this penetration?
- A1 hour
- B3/4 hour
- C2 hours
- D1 1/2 hours
Show answer & explanationAnswer & explanation
Correct answer: A. 1 hour
According to IBC 717.5.2, fire dampers in 1-hour fire-resistance-rated corridor walls must have a minimum 1-hour fire-resistance rating.
Why the other options are wrong
- B. This rating is typically for certain fire-resistance-rated ceilings, not 1-hour corridor walls.
- C. This rating is typically for fire barriers of 2 hours or more, or certain shaft enclosures.
- D. This rating is typically for fire barriers of 2 hours or more, or certain shaft enclosures.
Fire Damper Rating (Corridor)
Fire dampers installed in air distribution systems penetrating a fire-resistance-rated corridor wall must have a fire-resistance rating equal to or greater than the wall rating, up to a maximum of 1.5 hours for vertical penetrations.
- Prevents fire and smoke spread through ducts.
- Rating matches wall rating in corridors.
- IBC 717.5.2 provides requirements.
Memory trick: Ducts through fire walls need dampers, their rating matches the wall's clamor.