CHARLOTTE, N.C. — Crawl space encapsulation — sealing the crawl space with a heavy-duty vapor barrier and conditioning the air in the space — is one of the most effective long-term strategies for preventing mold growth and improving indoor air quality in homes with vented crawl spaces, according to building science researchers.
Traditional vented crawl spaces, which are designed to allow outdoor air to circulate beneath the floor, are counterproductive in humid climates. When warm, humid outdoor air enters a cool crawl space, moisture condenses on the cooler surfaces — including floor joists, subfloor, and insulation — creating ideal conditions for mold growth.
Encapsulation involves installing a 20-mil vapor barrier on the crawl space floor and walls, sealing all vents and penetrations, and conditioning the crawl space air with a dehumidifier or by connecting the space to the home's HVAC system. The result is a dry, conditioned space that does not support mold growth.
Building science research from the Advanced Energy Corporation and the Building Science Corporation shows that encapsulated crawl spaces have significantly lower moisture levels, lower mold spore counts, and better energy efficiency than vented crawl spaces — with energy savings of 15 to 20 percent in heating and cooling costs in some climates.
The cost of crawl space encapsulation typically ranges from $3,000 to $8,000 for a typical residential crawl space, depending on size and condition. Restoration contractors who offer encapsulation as a post-remediation service can provide homeowners with a long-term solution that reduces the risk of mold recurrence.
