CSLB General Building (B)Finishes and Building EnvelopeHard
A contractor is roofing a home located in a designated mountain area with a documented history of ice dam formation. Per California Residential Code requirements for such areas, an ice barrier membrane must extend from the roof eave edge to a point how far up the roof, measured horizontally inside the exterior wall line of the building?
- A18 inches
- B24 inches
- C12 inches
- D36 inches
Show answer & explanationAnswer & explanation
Correct answer: B. 24 inches
In areas with a history of ice damming, code requires an ice barrier (self-adhering waterproof membrane) to extend from the eave edge up the roof slope to a point at least 24 inches inside the exterior wall line of the building, protecting the roof deck from water backup caused by ice dams at the eave.
Why the other options are wrong
- A. 18 inches falls short of the code-required minimum extension.
- C. 12 inches is insufficient to protect against typical ice dam backup distances.
- D. 36 inches exceeds the code minimum requirement, though additional coverage is not prohibited.
Ice Barrier Requirement
In regions with a history of ice damming, code requires a self-adhering ice barrier membrane at the eaves extending at least 24 inches inside the exterior wall line.
- Applies in designated cold/mountain regions per local code amendments
- Membrane is self-adhering, waterproof underlayment (not standard felt)
- Prevents water backup from ice dams from penetrating under shingles
Memory trick: Two feet inside the wall keeps the ice dam at bay.