Commercial Building Inspector B2Floor ConstructionMedium
A commercial building inspector is reviewing plans for a new six-story office building. The plans indicate that the flooring system for the upper floors consists of 8-inch deep precast concrete planks. According to the IBC, what is the minimum required fire-resistance rating for these floor assemblies when supporting more than one floor or a roof in a Type IB construction?
- A3 hours
- B1 hour
- C2 hours
- D4 hours
Show answer & explanationAnswer & explanation
Correct answer: C. 2 hours
For Type IB construction, floor construction (other than the first floor) that supports more than one floor or a roof is required to have a minimum 2-hour fire-resistance rating.
Why the other options are wrong
- A. 3 hours is required for higher fire-rated elements like structural frames or bearing walls in Type IA construction.
- B. 1 hour is typically for lower fire-rated conditions or specific components, not for main floor assemblies in Type IB.
- D. 4 hours is typically reserved for the most stringent fire-resistance requirements, such as structural frames in Type IA buildings.
Type IB Fire Rating
Type IB construction is a fire-resistive construction type where the building elements are noncombustible and have a higher fire-resistance rating than Type IIB, but lower than Type IA.
- Noncombustible construction.
- Floor assemblies supporting multiple floors/roofs require 2-hour rating.
- Bearing walls and structural frames typically require 2-hour rating.
Memory trick: Building types determine fire's might, check the table for your code's light.