Commercial Building Inspector B2Public Safety and Special ConstructionHard
A building inspector is reviewing the fire protection system for a new seven-story mixed-use building. The building has Group R-2 occupancies on floors 3-7 and Group B occupancies on floors 1-2. The building is equipped with an automatic sprinkler system throughout. What is the minimum required fire-resistance rating for the horizontal exit components, such as fire barriers or fire walls, separating the Group R-2 residential portions from the Group B business portions on the same floor?
- A4 hours
- B1 hour
- C2 hours
- D3 hours
Show answer & explanationAnswer & explanation
Correct answer: C. 2 hours
According to IBC Table 508.4 (Table 508.4, Row for B above R-2), the fire-resistance rating for separation between Group B and Group R-2 occupancies, when the R-2 is above the B, is 2 hours. This is for horizontal separation on the same floor as well, as the occupancy separation requirements apply horizontally and vertically.
Why the other options are wrong
- A. 4 hours is reserved for the most stringent fire wall requirements.
- B. 1 hour is insufficient for this occupancy separation with residential above business.
- D. 3 hours is typically for higher hazard separations or specific fire walls.
Occupancy Separation (B and R-2)
The fire-resistance rating required for fire barriers or fire walls separating different occupancy groups within a building, specifically Group B (Business) and Group R-2 (Residential), as defined in IBC Table 508.4.
- Applies to both horizontal and vertical separations.
- Rating depends on the specific occupancy groups involved.
- IBC Table 508.4 is the primary reference.
Memory trick: Separate occupancies: Check the table, find the groups, get the fire rating.