Crawl space foundation construction in Vancouver, WA and Clark County

How a crawl space foundation is built

It starts with a continuous footing dug below the frost line. Concrete stem walls go up from the footing to the height of the floor, with rebar tying the two together and anchor bolts set in the top so the framing can be bolted down. The floor is framed over the top, and the space underneath becomes the crawl space.

Crawl space or slab foundation?

A slab puts the floor right on the ground. A crawl space lifts it up, which makes plumbing and wiring easier to reach later and keeps the floor away from ground moisture. On a sloped lot, stem walls can step down with the grade where a slab would need a lot of fill. Your plans decide which one a building gets.

Keeping a crawl space dry

In our climate, moisture is the main thing to plan for. The ground inside a crawl space is usually covered with a plastic vapor barrier, the space is vented or sealed depending on the design, and the soil outside slopes away from the walls so rain doesn’t run in. Codes also call for room to crawl under the floor, usually at least 18 inches below the floor joists.