BCAB #1241 - Vapour Barrier; Article

Last updated on March 24, 2016

March 27, 1991

BCAB #1241

Re: Vapour Barrier; Article

Project Description

Residential wood frame construction.

Reason for Appeal

Article requires a vapour barrier to "protect the entire insulated wall surface."

Appellant's Position

The appellant does not feel the intent of Article is to require the vapour barrier to be installed in the rim joist area (the spaces between the ends of the floor joists).

Building Official's Position

The building official contends that the rim joist area must be protected with a vapour barrier because shrinkage in the large number of joints would allow significant amounts of moisture to enter the structure. The building official cites Appendix item A-9.26.5 which states, in part, that "attention must be made to less obvious leakage paths such as ...... wall-ceiling intersections and gaps created by shrinkage of framing members."

Appeal Board Decision #1241

The Board considers Article is clear in requiring a vapour barrier over the entire insulated wall surface. The rim joist / box joist area is part of the insulated wall surface and a vapour barrier is required.

George R. Humphrey, Chair