I Want to Put a Vapor Barrier in My Crawl Space

Identification

• Vapor barriers are designed to keep moisture from evaporating inside your home through the soil. All homes should have vapor barriers in place in crawl spaces or dirt floor basements for adequate moisture control. Vapor barriers are commonly referred to as vapor diffusion retarders or VDRs. These products are constructed from materials designed to slow down the rate that moisture moves through the foundation of your home. Areas of the home prone to dampness and humidity such as crawl spaces and basements require vapor barriers, as well as ceilings and walls.

Types

• The type of vapor barrier used depends on where in your home it is being installed. Vapor barrier materials are flexible, thin and usually constructed from stainless steel, plastic or rigid foam boards. According to the United States Department of Energy, a 6 millimeter polyethylene vapor barrier provides adequate protection for moisture when placed in crawl spaces.

Installation

• Installing vapor barriers correctly is key to receiving maximum moisture control. The United States Department of Energy recommends placing your polyethylene vapor barrier across your crawl space floor, overlapping all seams. Tape the seams together and seal the barrier 6 inches up the walls. For additional protection, consider applying approximately 2 inches of concrete poured over the vapor barrier.

Considerations

• Controlling moisture in your crawl space is important because when moisture comes through the foundation of the home, it increases the humidity level in the entire house. Increased humidity can cause mold growth, which can damage your home and compromise your health. Reducing moisture outside the home can also keep humidity levels low and reduce damage from leaking water. Keep all downspouts and gutters clean and free of plant material such as leaves and twigs. Clogged gutters can cause water to leak inside your home. The ground outside your home must be graded in a manner that directs moisture away from your home. Check the ground to be sure it is sloped away from your home, so rainwater does not seep into the foundation.