BCAB #1674 - Capillary Break behind Siding, Div. A, Part 1, Clauses & (k) & Article & Div. B, Part 9, Sentences &

September 23, 2010

BCAB #1674

Re: Capillary Break behind Siding, Div. A, Part 1, Clauses & (k) & Article & Div. B, Part 9, Sentences &

Project Description
The project in question is the replacement of the cladding on an existing single family dwelling originally built in 1974. The original stucco cladding system was replaced with new building paper and fibre-cement panel and lap siding without a capillary break behind the siding.

Reason for Appeal
Clause in Division A states the Building Code applies to “an alteration to any building” and Clause (k) says it applies to “… the … replacement … of materials … regulated by this Code.” Article states “where a building is altered, rehabilitated, renovated or repaired … the level of … building performance shall not be decreased below a level that already exists.” Sentence in Division B requires exterior walls to minimize the ingress of precipitation into the assembly and prevent it from getting into the building’s interior unless the walls “are protected from precipitation.” Assuming the exterior walls are not protected from precipitation, Sentence requires a capillary break between the first plane of protection (siding) and the second plane of protection (building paper).

Appellant’s Position
The appellants were unaware of the Code provisions for a capillary break and did not apply for a building permit. However, they contend that there was no evidence of water ingress behind the cracked and deteriorated stucco so the 28” overhang and surrounding site conditions appear to provide a degree of protection from precipitation. The new cladding system is considerably better than the old stucco it replaced and has endured two wet winters with no indication of failure so should be acceptable without a capillary break.

Building Official's Position
The building official maintains that the new cladding system is required to conform to the current Code and the climatic conditions for the site dictate the need for a capillary break. Information in the Appendix indicates the type of cladding installed generally provides little drainage and should be installed over a capillary break unlike some types of cladding (strip vinyl and metal) which provide their own capillary break.

Appeal Board Decision #1674
It is the determination of the Board that the Building Code does apply to the work done and the Board notes that Article provides that work done to existing buildings shall not result in a level of performance lower than previously existed. Since the work is completed, the Board encourages the appellant to pursue an alternate solution to resolve this situation.

George Humphrey, Chair