Commercial Building Inspector B2General Administration, Permits, and PlansHard
A commercial building inspector is reviewing plans for a new 10-story Group R-2 apartment building. The building is designed as Type I-A construction. What is the minimum fire-resistance rating required for the floor construction, including the supporting beams and girders, below the first story?
- A3 hours
- B4 hours
- C1 hour
- D2 hours
Show answer & explanationAnswer & explanation
Correct answer: A. 3 hours
For Type I-A construction, IBC Table 601 specifies a minimum 3-hour fire-resistance rating for the floor construction, including supporting beams and girders, below the first story. This high rating is crucial for the most fire-resistive construction type.
Why the other options are wrong
- B. 4 hours is typically reserved for fire walls or specific elements in very high hazard occupancies, not standard floor construction.
- C. 1 hour is typically for less protected types or specific non-bearing elements.
- D. 2 hours is common for floor construction in Type I-B or II-A, but not Type I-A below the first story.
Type I-A Floor Construction Rating
In Type I-A construction, the most fire-resistive type, floor construction and its supports (including below the first story) must have a minimum 3-hour fire-resistance rating.
- Type I-A uses noncombustible materials.
- Highest level of fire protection.
- Specific ratings for various structural elements.
Memory trick: Super-strong Type 1-A floors below ground always need three hours of fire protection.