Residential Building Inspector B1Wall Construction and Wall CoveringsHard
During a framing inspection, an inspector observes a two-story residential dwelling where fireblocking is being installed. Plastic piping is penetrating a fireblock in a concealed stud space. What is the maximum aggregate area of openings for such penetrations in a single fireblock?
- A16 square inches
- B25 square inches
- C100 square inches
- D144 square inches
Show answer & explanationAnswer & explanation
Correct answer: C. 100 square inches
According to IRC R302.11.1.1, the aggregate area of openings for plumbing, electrical, and mechanical systems through a single fireblock shall not exceed 100 square inches, and the annular space around penetrations must be filled with an approved material.
Why the other options are wrong
- A. 16 square inches is too restrictive and not specified as the maximum aggregate area for penetrations through fireblocking.
- B. 25 square inches is not the specified maximum aggregate area for penetrations through fireblocking.
- D. 144 square inches (1 square foot) is excessive and would compromise the effectiveness of the fireblock.
Fireblock Penetration Limits
Fireblocks can be penetrated by utilities, but the aggregate area of openings is limited to maintain fire resistance, and annular spaces must be sealed.
- Maximum aggregate area: 100 square inches.
- Annular spaces around penetrations must be filled.
- Applies to plumbing, electrical, and mechanical penetrations.
Memory trick: Fireblocking is like a dam for fire, even small holes need sealing, but a big hole is a no-go.