subfloor, crawl space

Three different crawl space types

For the purpose of discussing moisture management, crawl spaces can be classified into three different types.

We refer to open pier-and- beam foundations as open crawl spaces. (See Figure 1, page 3.) Open crawl spaces may have a continuous wall on just the front side and be open on the other sides.

We refer to crawl spaces with continuous perimeter walls that include vents to the outside as wall-vented crawl spaces. (See Figure 2.)

Finally, we refer to crawl spaces with continuous perimeter walls with no vents as closed crawl spaces. (See Figure 3.)

A closed crawl space, with

regard to air and water vapor movement, is effectively part of the interior space and is intended to be isolated from the ground and the exterior.