Fiberglass insulation, or batting, can be an effective means of insulating crawl spaces.
Insulating a crawl space with fiberglass insulation, also referred to as batting, can save energy costs while sealing out cold air drafts and helping control moisture in the home. How batting is installed depends on whether the crawl space is vented or not. Vented crawl spaces have small, screened openings that let air circulate through the space. Does this Spark an idea?
Vented Crawl Spaces
1. Cover the ground with sheets of 6-mil plastic film. Overlap each course by approximately 1 foot and up the side of each wall approximately 6 inches. Secure the film in place along the walls with duct tape. The plastic will provide a moisture barrier for the crawl space.
2. Hold the overlaps in place with a brick or stone spaced every 8 to 10 feet.
3. Unroll the batting and fit it securely between the floor joists. Use Kraft-paper-backed batting for vented crawl spaces, and keep the paper side facing up toward the subfloor. Ensure a snug fit so that no air space exists between the insulation and the flooring. Cut slits in the batting with a utility knife to accommodate existing pipes and electrical conduit.
4. Staple the batting in place by running staples through the fold-out flanges on either side of the insulation and into the edges or sides of joists. If no flanges are present, hammer nails into the edges of joists and twist stiff wire around them and across to the next joist to act as hangers. Push the wire up into the batting just enough to make sure no air space exists, but not enough to compress the insulation.
5. Repeat the process between each set of floor joists all the way down the length of each joist.
Nonvented Crawl Spaces
6. Cover the ground with sheets of 6-mil plastic film. Overlap each course by approximately 1 foot and up the side of each wall about 6 inches. Secure the film in place along the walls with duct tape. The plastic will provide a moisture barrier for the crawl space.
7. Hold the overlaps in place with a brick or stone spaced every 8 to 10 feet.
8. Cut the insulation with a utility knife so it will fit between the floor joists all along the rim joists. These latter joists run all along the edges of the floor joists and are what the floor joists are nailed into. Push the insulation into place. Either Kraft-paper-backed or standard nonfaced batting insulation will work for rim-joist application.
9. Cut lengths of standard nonfaced batting insulation long enough to run from the home’s sill plate to approximately 2 feet past where the crawl space wall meets the floor. The sill plate is framing lumber about 2 inches thick that runs along the top of the concrete or concrete block crawl space wall.
10. Secure the batting in place along the top by nailing a furring strip that sandwiches the top edge of the insulation between the furring strip and the sill plate.
11. Push the batting up as close as possible to the corners where the crawl space walls meet the floor and lay a 2×4 on top of the batting to hold it down.
12. Repeat the process until all the crawl space walls are covered in batting.