Crawlspace Encapsulation in Mobile, AL

The vented crawlspace was a building code idea from the 1940s based on cooler, drier northern climates. In Mobile, where outdoor relative humidity averages 75% and tops 90% during summer, those open vents do the opposite of what they were designed to do — they pump moisture-laden air into a cooler space underneath your house, where it condenses on framing, ductwork, and the underside of your subfloor. The result is rotting joists, rusted HVAC components, and a constant musty smell that pushes up through floor penetrations into the living space.

Older homes in Midtown, Oakleigh, and the historic districts off Government Street are especially vulnerable because their original brick pier crawlspaces were never sealed and their floor systems are heart pine that turns to sponge once it stays above 18% moisture content for any length of time.

A proper encapsulation is not just laying plastic on the dirt — it is a complete sealed envelope. Our standard scope includes:

• 20-mil reinforced vapor barrier covering the entire ground surface, lapped and seam-taped to manufacturer spec.
• Vapor barrier extended up and mechanically fastened to the foundation walls and piers, sealed at every transition.
• All foundation vents permanently sealed with rigid insulated covers.
• Crawlspace access door replaced with an insulated, weatherstripped airtight door.
• Conditioned-space dehumidifier sized to crawlspace volume, with condensate plumbed to daylight or to a condensate pump.
• Optional rigid foam insulation on perimeter walls for code-compliant conditioned crawlspaces.

Once installed, the dehumidifier holds the space at 50-55% RH year-round, which is below the threshold where mold can germinate and wood can absorb destructive moisture.

About 40% of the air in a typical Mobile home with a vented crawlspace comes up through the floor system — and in summer, that air is hotter and wetter than the conditioned air your HVAC just paid to cool. Sealing the crawlspace typically cuts cooling costs by 15-25% and stabilizes humidity inside the house, which means your AC runs shorter cycles and your indoor RH stays in the 45-55% comfort band instead of the 60-65% range that feels sticky even at 74 degrees.

The indoor air quality improvement is the part homeowners notice fastest. Within a month of encapsulation, the musty smell that lives in carpets and HVAC returns is gone, and households with allergy or asthma sensitivities almost always report fewer symptoms. Structurally, you stop the slow rot cycle that eventually requires full subfloor replacement — a $20K+ job we would much rather you avoid.

Full encapsulation for a typical 1,200-1,800 sq ft crawlspace in Mobile runs $7,000-$14,000 depending on access, debris removal needs, drainage requirements, and whether perimeter insulation is added. Dehumidifier upgrades and sump systems for chronic water intrusion are priced separately. Most jobs are completed in 2-4 working days with minimal disruption to the household.

Vapor barrier installation carries a 20-year warranty against tearing or seam failure under normal conditions. Dehumidifiers carry the manufacturer 5-year warranty, which we register on your behalf at completion.

We provide crawlspace encapsulation across Mobile, Midtown, West Mobile, Saraland, Semmes, Theodore, Tillman Corner, and Chickasaw. Free written estimates with a full crawlspace inspection and moisture readings are typically scheduled within a week. Call (251) 318-8331 and we will get someone under the house.