Squirming through your crawlspace and adding insulation may seem like a feat of Indiana Jonesian
proportions. (The potential claustrophobia and spiders may be daunting for even the most hardcore do-it-yourselfer. Hence the beauty of contractors!) The epicness of the task is
matched by its possible energy savings: Uninsulated crawlspaces are a major source of heat loss in a typical home (as much as 15 percent). In addition to keeping your home cozier,
crawlspace insulation can help prevent frozen water pipes, make your house quieter, and save money on home heating and cooling.
Where you install crawlspace insulation depends on whether the crawlspace is ventilated. In ventilated crawlspaces, only the subfloor is insulated. In unventilated crawlspaces, the crawlspace walls need insulation. (You'll be using
batting or rigid foam insulation.) Insulating the entire interior area of crawlspace walls to the recommended R-value can keep the crawlspace—and floor above it—warmer in chilly months, in conjunction with
proper sealing.
1. Address any exterior drainage problems, block all ventilation between the exterior and the crawlspace, and install a heavy-duty vapor retarder on the ground to keep out moisture.
2. Measure the wall space and purchase the necessary amount of batting or rigid foam insulation and supplies.
3. Attach rigid foam insulation to the crawlspace walls with an adhesive. Or, attach insulation batts to the sill plate by using furring strips and drape them down the walls; extend the batting over 2 feet of floor space.
4. If necessary for your area, apply a termite barrier or leave adequate space along the top of the walls for regular termite inspection.
Choose the right product for safety. Because the insulation will be exposed, use either an unfaced product or one with the appropriate flame-spread rating.
Insulate to the correct R-value. The ideal R-value for insulating your crawlspace will depend on your climate.
If you are hiring a contractor, choose carefully. When comparing contractors' bids, make sure they are for the same R-value, not just the same number of inches.
Insulate the entire wall area. Gaps will allow heat to escape and reduce the benefit of the project, so do not leave any (except those required for termite inspection).