If your home is built on a crawl space, it probably contains moisture. This moisture causes mold and mildew, attracts destructive insects and reduces the quality of the air in your home. A vapor barrier may help keep these crawl space hazards out of your living area, and can allow you to safely use your crawl space for storage. Here's what you need to know about installing a vapor barrier in your crawl space.
The Right Vapor Barrier
Choose the right vapor barrier for your space. Crawl space vapor barriers are made of polyethylene and may be reinforced or unreinforced. There are other materials that are sometimes used in damp crawl spaces but polyethylene vapor barriers are the most popular choice for keeping your crawl space dry.
The condition of your space will determine the thickness of the barrier. Vapor barriers range in thickness from about 8 to about 20mm. If the bottom of your crawl space is smooth dirt or sand and doesn't get a lot of traffic, an 8mm vapor barrier will do the trick. If your space sees moderate or heavy traffic, or if you want to store possessions in the space, use a 12mm vapor barrier. Rough dirt or concrete surfaces with heavy traffic call for a 20mm vapor barrier.
Lining the Barrier
In some cases, you may want a layer of felt or other material under the vapor barrier. This will smooth out the surface of the floor of the crawl space and prevent any sharp rocks or pieces of concrete from penetrating the barrier and rendering it useless.
Sealing and Taping
The best possible vapor barrier will be ineffective if it is not installed correctly. In order for a vapor barrier to work, it must be properly sealed or taped. This means taping any seams in the vapor barrier, and taping the barrier itself to the home's insulation. Leaving any part of the vapor barrier unsealed negates the advantage of the barrier by allowing moisture to seep into your crawl space.
Installing a vapor barrier in your crawl space can improve the air quality in your home and can give you usable storage space, so try here. Vapor barriers can be installed by do-it-yourselfers, but professional installers can do the job quickly and efficiently, and they know the pitfalls to watch out for. A professional will also know if you need a dehumidifier or other remediation for your wet or damp crawl space.