A commercial building inspector is reviewing plans for a new 4-story Group S-2 (parking garage) building. The garage will be entirely open on two sides and sprinklered. What is the minimum required fire-resistance rating for the roof construction of this building?
- A0 hours
- B2 hours
- C1.5 hours
- D1 hour
Show answer & explanationAnswer & explanation
Correct answer: A. 0 hours
According to IBC Table 601, for Type II-B construction (common for open parking garages) or even Type II-A, the roof construction is permitted to be 0-hour fire-resistance rated (noncombustible) if the building is sprinklered and meets the conditions for an open parking garage, including being open on two or more sides. IBC 406.5 further details open parking garage requirements.
Why the other options are wrong
- B. 2 hours is typically for structural frames or floors in higher-rated construction types.
- C. 1.5 hours is not a standard fire-resistance rating for roof construction in this context.
- D. 1 hour is typically for floors or other elements in Type II-A, or for exterior walls with certain distances to property lines.
Open Parking Garage Roof Rating
For open parking garages, which are designed with natural ventilation and often sprinklered, the International Building Code (IBC) may permit non-rated (0-hour) fire-resistance for the roof construction, given their reduced fire hazard due to openness and fire suppression systems.
- Applies to open parking garages.
- Often 0-hour rating permitted for roof.
- Requires natural ventilation/open sides.
- Sprinklers often a factor.
Memory trick: The 'Open Air Roof' gets a pass on rating if it's breezy and wet.