CSLB General Building (B)Mechanical, Electrical, Plumbing CoordinationHard
A three-story custom home has a continuous combustible soffit and cornice running the full length of the exterior wall. Per fire blocking requirements, concealed spaces behind such combustible construction must be blocked at intervals not exceeding:
- A30 feet
- B20 feet
- C10 feet
- D40 feet
Show answer & explanationAnswer & explanation
Correct answer: B. 20 feet
Concealed spaces behind combustible cornices and soffits must be fire blocked at maximum 20-foot intervals to interrupt fire travel along the length of continuous concealed horizontal spaces.
Why the other options are wrong
- A. 30 feet exceeds the maximum allowable spacing for this concealed horizontal space.
- C. 10 feet is the vertical stud cavity requirement, not the cornice/soffit interval.
- D. 40 feet is far beyond the code-required maximum interval.
Cornice/Soffit Fire Blocking
Concealed spaces behind combustible cornices and soffits require fire blocking at maximum 20-foot intervals to limit horizontal fire spread.
- Separate requirement from the 10-foot vertical stud cavity rule
- Applies to continuous horizontal concealed spaces at eaves
- Prevents fire from running unchecked along roof edges
Memory trick: Twenty feet along the eave, keeps the fire well-behaved.