A building official is inspecting the fire resistance-rated construction of a new six-story apartment building (Group R-2). According to IBC 703.3, what is the maximum allowable dimension for an opening in a fire-resistance-rated wall that is NOT permitted to be protected with an opening protective (e.g., fire door or fire window)?
- A16 square inches (0.010 m²)
- B150 square inches (0.097 m²)
- C100 square inches (0.065 m²)
- D25 square inches (0.016 m²)
Show answer & explanationAnswer & explanation
Correct answer: C. 100 square inches (0.065 m²)
IBC 703.3 permits openings in fire-resistance-rated assemblies without opening protectives provided the aggregate area of such openings does not exceed 100 square inches (0.065 m²) in any 100 square feet (9.3 m²) of wall area, and no dimension exceeds 10 inches (254 mm). The question asks for the maximum dimension for an opening that is NOT permitted to be protected, meaning it falls under this exception for small, unprotected openings.
Why the other options are wrong
- A. 16 square inches is too small; the maximum size for an unprotected opening is larger.
- B. 150 square inches exceeds the limit for unprotected openings, requiring a fire-rated assembly.
- D. 25 square inches is also too small; the maximum size for an unprotected opening is larger.
Unprotected Openings in Fire Walls
IBC 703.3 allows small, unprotected openings in fire-resistance-rated walls, provided the aggregate area does not exceed 100 square inches per 100 square feet of wall area, and no single dimension exceeds 10 inches.
- Applies to penetrations for pipes, conduits, etc.
- Must meet aggregate area and individual dimension limits.
- Does not apply to openings for doors or windows, which always require protection.
Memory trick: A C-note (100) for an opening, no more than 10 inches high or wide, keeps the fire from growing.