Crawl Spaces

Un-insulated Crawl Spaces are one of the biggest areas of heating and cooling losses for homes – that have them. Normally they are created as the result of a add-on to the homes square footage, and instead of creating a full height basement, small foundation walls are used.  The older crawl spaces often have a dirt floor.  They may have some open ventilation or access to the main basement or they may be sealed off from the rest of the home.  These areas tend to have a higher humidity due to moisture coming in from the dirt floor.  Since they are normally an add-on room, a heat source is needed and it was simple to run a HVAC duct through.  However, the efficiency of the ductwork can be reduced by as much as 50%. That said, it is necessary to understand that effective crawl space insulation cannot be achieved without proper measures to control moisture in that environment or without using waterproof materials to insulate the area.

Most insulation contractors will recommend a waterproof ground cover first, which will keep some of the ground water from evaporating into the crawl, but will not address the water that seeps through the walls. To completely control moisture in the crawl space, both the floor and the walls should be lined with something that acts as a vapor barrier, completely isolating the area from ground and wall moisture. In our Madison, Wisconsin climate, a ground vapor barrier can be combined with foam board insulation, to provide both a vapor barrier and thermal protection.

The most popular and widespread method of crawl space insulation, – applying fiberglass insulation bats between the floor joists of a vented crawl space- is also the main cause of most crawl space mold disasters. Fiberglass soaks moisture like a sponge supporting mold growth on its paper facing. To make matters worse, damp fiberglass loses it is R-Value, becoming useless as insulation, and as it sags, it opens holes in the insulation blanket, allowing the air to leak into the living area. We recommend the following:

Closed Cell Spray Foam Insulation – Closed cell spray foam, is an excellent choice for crawl spaces. It expands after application, air sealing gaps and fitting snugly around pipes, wiring, ducts and fixtures.

Rigid Foam Board – Rigid foam is waterproof, does not absorb moisture, and will not support mold growth, so it’s an excellent choice in moist areas like basements and crawl spaces.

Often homeowners complain of cold drafts that can be felt coming from the floors above a crawl space. This is why air sealing is fundamental. Crawl space insulation without air sealing is not as effective. Crawl space insulation is one of the home improvements that bring the best results and the most savings per each dollar invested.