Commercial Building Inspector B2General Administration, Permits, and PlansMedium
A commercial building inspector is reviewing plans for a new 6-story Group B office building. The building will have an automatic sprinkler system throughout. What is the minimum required fire-resistance rating for the structural frame of this Type I-A construction?
- A4 hours
- B1 hour
- C2 hours
- D3 hours
Show answer & explanationAnswer & explanation
Correct answer: D. 3 hours
For Type I-A construction, the IBC specifies a minimum 3-hour fire-resistance rating for the structural frame, regardless of the presence of an automatic sprinkler system, due to its inherent high level of fire protection.
Why the other options are wrong
- A. 4 hours is reserved for specific elements like exterior bearing walls in Type I-A or higher-risk scenarios.
- B. 1 hour is typically for lower-rated construction types or non-bearing walls.
- C. 2 hours is common for Type I-B or Type II-A construction, but not Type I-A structural frames.
Type I-A Construction Structural Frame Rating
Type I-A construction represents the highest level of fire-resistive construction. The structural frame, which includes columns, girders, trusses, and bearing walls, must maintain its structural integrity for a specified duration under fire exposure.
- Highest fire-resistance classification.
- Minimum 3-hour rating for structural frame.
- Automatic sprinklers do not reduce this specific rating.
Memory trick: Imagine a 'Very Secure Structure' (VSS) where I-A means 'Iron Strong' for 3 hours.