BCAB #1096 - Crawl Space Ventilation, Article 9.18.3.1.

October 5, 1989

BCAB #1096

Re: Crawl Space Ventilation, Article 9.18.3.1.

With reference to your letter of August 28, 1989, regarding ventilation of the crawl space in a house. With respect to your problems with the New Home Warranty Program, these do not fall under the duties of the Appeal Board; we will therefore deal only with the question of compliance with the B.C. Building Code for the situation outlined in your letter. As the requirements for house and crawl space interrelate, with both apparently affecting your problems, we will clarify the general position.

The Code requires that a dwelling unit be ventilated. During the non-heating season Article 9.33.2.1. permits either natural or mechanical means to achieve this objective; during the heating season there is no choice, Article 9.33.3.1. requires the provision of a mechanical system. In the absence of natural ventilation to deal with the non-heating season this mechanical system must also accommodate the summer period under Article 9.33.3.4.

In the case of a crawl space, ventilation is mandatory under Article 9.18.3.1.; Article 9.18.3.2. specifically requires venting to the outside, unless the crawl space is used as a warm-air plenum or is vented to an adjacent basement. In an earlier decision, under Appeal #1009, we accepted an alternative, which was to deal with the crawl space as part of the heated enclosure of the building; for this purpose it would be required to comply fully with the provisions indicated for a dwelling unit in the previous paragraph.

The full details of your situation are not clear except for two points. The building in question is described as electrically heated, using ceiling-mounted radiant panels. Under these circumstances the crawl space is not a plenum, so the exemption in Article 9.18.3.5. does not apply; while some air is apparently being introduced through the crawl space this does not justify classifying it as a plenum.

There is also a statement that make-up air is drawn from a garage; if such is the case we should point out that the Code requires air from the exterior, and for this purpose a garage would be unacceptable.

We recommend that you apply the above principles to your situation, the limited information submitted suggests that you contravene the Building Code. For your information copies of earlier Appeals #1009, 1055, and 1055A are enclosed, these all deal with a similar situation.

J.C. Currie, Chair