Commercial Building Inspector B2General Administration, Permits, and PlansMedium
A commercial building inspector is reviewing plans for a new 3-story Group B office building. The building will have a total area of 25,000 square feet per floor. What is the minimum required fire-resistance rating for the structural frame of this Type III-A construction building?
- A0 hours
- B3 hours
- C2 hours
- D1 hour
Show answer & explanationAnswer & explanation
Correct answer: D. 1 hour
For Type III-A construction, the IBC specifies a minimum 1-hour fire-resistance rating for the structural frame. This rating applies to bearing walls, columns, and other elements of the structural frame.
Why the other options are wrong
- A. 0 hours is typically for unprotected noncombustible or light-frame construction types, not Type III-A.
- B. 3 hours is typically reserved for Type I-A construction or very specific high-hazard situations.
- C. 2 hours is typically required for more protected construction types (e.g., Type I-B, II-A) or specific elements in higher hazard occupancies.
Type III-A Construction Structural Frame Rating
Type III-A construction, also known as 'Protected Combustible,' requires a 1-hour fire-resistance rating for its structural frame, exterior bearing walls, and floor/roof construction.
- Uses combustible materials for major structural elements.
- Requires 1-hour fire resistance for structural frame.
- Exterior walls typically noncombustible or 2-hour fire-rated.
Memory trick: Three-A buildings need a sturdy 1-hour frame to protect their wood, always.