CSLB General Building (B)Mechanical, Electrical, Plumbing CoordinationMedium
During a rough-in inspection, the inspector notes that the concealed space between the stair stringers and the wall was not sealed at the top and bottom of the stair run. What code requirement was violated?
- AEgress width requirements for stairways
- BDraft stopping requirements for large attics
- CFire blocking requirements at stair stringers
- DSound transmission class requirements for stairs
Show answer & explanationAnswer & explanation
Correct answer: C. Fire blocking requirements at stair stringers
Fire blocking must be installed in the concealed space between stair stringers and the wall at the top and bottom of the stair run to prevent fire and smoke from traveling through this hidden vertical channel.
Why the other options are wrong
- A. Egress width is a dimensional life-safety requirement, unrelated to concealed cavity sealing.
- B. Draft stopping applies to large concealed floor/ceiling and attic spaces, not stair stringers.
- D. Sound ratings are unrelated to concealed fire spread paths.
Stair Stringer Fire Blocking
Code requires fire blocking in concealed spaces between stair stringers and walls at the top and bottom of each stair run.
- Prevents fire from traveling through hidden stair cavities
- Required at both top and bottom of the stair run
- Distinct from fire blocking required in vertical stud cavities
Memory trick: Seal the stairs top and bottom, or fire climbs unstoppin'.