How To Fix A Crawl Space Foundation

The Best Way to Encapsulate Your Crawl Space

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Prepare Yourself

Encapsulating the crawl space below your home transforms it from a dark, scary, damp area to a dry, sealed environment that improves the conditions of your living space. Both the Environmental Protection Agency and U.S. Department of Energy recommend sealing your crawl space because it improves the air quality in your home, reduces energy costs and prevents moisture-related damage. It also gives you cooler floors in the summer and warmer floors in the winter, all while reducing the odds of pests entering your home through the foundation.

Stay safe by making sure you're physically able to navigate the tight space. It requires plenty of crawling, stooping, enduring hot or cold temperatures and being confined to a small area for a period of time. Wear protective clothing such as long pants, a shirt with long sleeves, work boots with sturdy soles, safety gloves and a mask or toxic dust respirator. Additionally, include a ground fault circuit interrupter (GFI adapter) in your tool kit to provide protection against shocks in a damp space, suggests NT Supply.

Prepare the Space

Before encapsulating your crawl space, take care of any water leaks, loose wiring, mold growth and debris that isn't attached to the house. Don't skip this step. Sealing a space that has these issues may only cause future problems.

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Check for water leaks by looking for standing water and stains on the concrete walls. Solutions may include grading and plumbing repair. Look for loose wiring and tack it to the beams, and properly repair any damaged or exposed wiring. Call in a professional if needed to solve these issues at the source.

Clean mold growth and dust from joists and walls with a bleach-water solution. If you have gas appliances, perform a carbon monoxide test to ensure dangerous gases don't backdraft into your home. Remove discarded building materials and any other debris that isn't dirt from the crawl space. Be especially mindful of nails or other sharp objects that might puncture the vapor barrier, thereby breaking the encapsulation seal.

Cover Beams, Piers and Ground

Because freedom of mobility is an issue in a cramped crawl space, do as much as you can outside of the area, including measuring, cutting and applying two-sided backing tape to the vapor barrier. Lining the crawl space involves several steps.

Measure and cut the vapor barrier so that it covers all but three inches of the perimeter beam and overlaps on the floor at least 12 inches. Apply backing tape to the barrier. Fold and roll it so it's easy to carry. In the crawl space, apply a bead of construction adhesive to the concrete. Line the perimeter beam with the vapor barrier, using the backing tape to hold it in place. Ensure a good seal. Drill holes for foundation pins, and hammer them in place.

Prepare the vapor barrier to cover all four sides of each pier and overlap on the ground. Apply as you did with the perimeter beam. Lay the ground cover in sections over the existing vapor barrier. Use backing tape to seal all seams.

Seal Joist Bays and Dehumidify

As you're lining the perimeter of the crawl space, you also need to seal the area between joists so that the crawl space is completely free of drafts. Do this using foam insulation and foaming caulk.

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Measure the height and width of each joist bay. Cut foam insulation to fit inside it. Push the foam into place and spray a mist of water over the edges to cure it. Add generous beads of foaming caulk around all of the edges to create an airtight seal between the foam and the foundation of the house.

Encapsulation is complete once you add a conditioning system to the crawl space. This creates an added layer of protection against moisture accumulating in your crawl space. Condition the space by either installing a crawl space dehumidifier or using your existing air conditioner. Both methods keep air circulating in your crawl space so it's less likely to become contaminated with allergens. Circulating air also keeps temperatures constant to help your appliances run more efficiently.