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 is designed with Type II-B construction. What is the minimum fire-resistance rating required for the roof construction, including its supporting beams and girders?
- A1.5 hours
- B0.5 hours
- C0 hours
- D1 hour
Show answer & explanationAnswer & explanation
Correct answer: C. 0 hours
For Type II-B construction, IBC Table 601 specifies a minimum 0-hour fire-resistance rating for the roof construction, including its supporting beams and girders. This means no specific fire rating is required for these elements.
Why the other options are wrong
- A. 1.5 hours is typically for roof construction in Type I-A, a much higher fire-rated construction type.
- B. 0.5 hours (30 minutes) is not a standard fire-resistance rating for general roof construction in IBC.
- D. 1 hour is typically for more protected types or specific elements like fire barriers, not for Type II-B roof construction.
Type II-B Roof Construction Rating
In Type II-B construction, which is unprotected noncombustible, the roof construction and its supporting elements are permitted to have a 0-hour fire-resistance rating.
- Type II-B uses noncombustible materials.
- Least fire-resistive of the noncombustible types.
- Many elements have 0-hour ratings.
Memory trick: Two-B's roof is open to the elements, zero protection needed.