Footings and Foundations For Crawl Spaces

Crawl spaces are enclosed spaces between the underside of a floor assembly and the ground below, where the clearance is less than the minimum 2 m (6 ft. 6 in.) required for a basement and less than 25 per cent of their area above ground is open to the outdoors. Crawl spaces are often used to give access to ducts, pipes, cables and other utilities and can be heated (conditioned) or unheated (unconditioned). If a crawl space is unheated, it is essential to have an effective air barrier between the conditioned and unconditioned space.

As for other types of foundations, footings for crawl spaces must be placed at a depth below grade determined by soil conditions and frost penetration (see Table 3 on p. 265). Footing sizes are generally the same as those used to support basement walls. Crawl space walls may be built of concrete, ICFs, concrete masonry units or preserved wood. Since the inside grade is seldom much lower than the outside grade, the thickness of the foundation walls may be less than those enclosing a basement. Crawl space insulation, which can be installed either at the perimeter of the foundation or in the floor framing under the living space.

Source : Canada Mortgage and Housing Corporation (CMHC)