Commercial Building Inspector B2General Administration, Permits, and PlansMedium
A commercial building inspector is reviewing plans for a proposed 3-story office building. The plans indicate that the building will have exterior walls constructed of 8-inch concrete masonry units (CMU), while the interior structural frame, floors, and roof will be constructed of unprotected wood. What type of construction does this building most closely represent according to the IBC?
- AType I-B
- BType III-B
- CType II-B
- DType V-A
Show answer & explanationAnswer & explanation
Correct answer: B. Type III-B
Type III-B construction is characterized by exterior walls of noncombustible construction (like CMU) and interior structural elements, floors, and roofs of combustible materials (like unprotected wood), without fire-resistance ratings.
Why the other options are wrong
- A. Type I-B requires noncombustible construction throughout with fire-resistance ratings.
- C. Type II-B requires noncombustible construction throughout with no fire-resistance ratings.
- D. Type V-A requires all major building elements to be of combustible material, with a 1-hour fire-resistance rating.
Type III-B Construction
A type of construction where exterior bearing walls and nonbearing walls are of approved noncombustible materials, and interior structural elements are of any material permitted by the code, typically combustible, with no fire-resistance rating required for interior elements.
- Exterior walls are noncombustible (e.g., masonry, concrete).
- Interior structural frame, floors, and roof are combustible (e.g., wood).
- No fire-resistance rating is generally required for interior elements in Type III-B.
Memory trick: Type 'III' is like a tough 'shell' (non-combustible exterior) with a 'soft' (combustible interior) center, and 'B' means 'Bare' (unprotected).