Crawl space encapsulation seals your crawl space off from ground moisture and outside air with a heavy-duty vapor barrier, sealed vents, and controlled dehumidification. Air Sense Environmental installs complete encapsulation systems across St. Louis, MO, St. Louis County, St. Charles County, and the Illinois Metro East, pairing professional-grade sealing with AprilAire dehumidifiers to keep humidity in the healthy range year-round.
Up to half the air you breathe on your first floor rises from your crawl space. In our region’s humid summers, an open or vented crawl space pulls in moist air that condenses under your home, feeding mold, rotting wood framing, and attracting pests. Encapsulation stops that cycle at the source.
Musty smell on the first floor, especially in summer
Visible mold, mildew, or white fuzzy growth on floor joists
Sagging or cupping hardwood floors above the crawl space
Standing water or damp soil after rain
Insects, spiders, or rodents getting in through vents
Rising cooling bills as your AC fights humid air from below
Allergy symptoms that improve when you leave the house
If two or more of these sound familiar, an inspection is worth your time. The assessment is free and takes about an hour.
Every Air Sense Environmental encapsulation is a complete system, not just a plastic liner:
Heavy-duty vapor barrier. A thick, reinforced liner sealed across the floor and up the foundation walls, with taped seams and mechanical fastening.
Vent and gap sealing. Outside air stays outside. We seal vents, rim joists, and penetrations so humid summer air cannot condense under your home.
AprilAire dehumidification. A dedicated crawl space dehumidifier holds humidity at a safe level automatically and drains without emptying buckets. AprilAire has led indoor air quality since 1938, and these units are energy-efficient and built to run for years with minimal maintenance.
Drainage correction when needed. If water is entering, we address the drainage before sealing, so you never trap a problem under the liner.
Free assessment. We inspect your crawl space, measure humidity and moisture content, and photograph existing damage so you see exactly what we see.
Custom plan and transparent estimate. Every home is different. You get a written scope and price with no surprises before any work starts.
Professional installation. Our experienced technicians complete most encapsulations in one to two days, including cleanup.
Verification and support. We confirm humidity targets after installation and remain available for ongoing maintenance and monitoring.
Radon enters homes through exposed soil, and an open crawl space is a direct pathway. A sealed vapor barrier is also the foundation of sub-membrane radon mitigation, the standard method for crawl space homes. If your home has never been tested, the EPA action level is 4.0 pCi/L, and testing takes 48 hours. As an IEMA-licensed radon contractor (#RNM20232346), Air Sense Environmental can test during your encapsulation assessment and, if needed, design the encapsulation to double as your radon mitigation base layer. One visit, both problems solved.
Every crawl space is different, so pricing depends on square footage, current condition, and whether mold removal or drainage correction is needed first. Think of encapsulation as a long-term investment: a properly sealed crawl space lowers energy bills, protects your framing, and prevents far more expensive structural repairs later. For a detailed breakdown of typical price ranges, see our guide to crawl space encapsulation costs in St. Louis. The most accurate number is a free on-site estimate, written and transparent, with no obligation.
A professionally installed vapor barrier lasts 15 to 25 years. The AprilAire dehumidifier carries a manufacturer warranty and typically runs 10+ years with basic filter maintenance.
Thin DIY liners and unsealed seams usually fail within a few seasons, and sealing vents without adding dehumidification can make moisture worse. If drainage, mold, or radon are involved, professional assessment matters even more.
Usually yes. Your HVAC no longer fights humid air rising from below, and sealed vents stop winter drafts under your floors. Many homeowners notice the difference in the first summer.
We encapsulate crawl spaces across the greater St. Louis metro and Metro East, including St. Louis County, St. Charles County, Madison County, and St. Clair County. Call 314-664-9807 to confirm your address.
Related from Air Sense Environmental: Radon Mitigation, Radon Testing, Indoor Air Quality Testing, and Reviews & Projects.
Stop the moisture cycle before it reaches your living space. Call 314-664-9807 for your free crawl space assessment.
Air Sense Environmental provides crawl space encapsulation across the greater St. Louis metro and Metro East. Find your area:
