Full Crawl Space Encapsulation System
A full system installs a 20-mil vapor barrier on floor and walls, seals foundation vents, adds a dehumidifier, and may include drainage when needed.
This combination is what Nashville's clay soil, humidity, and pre-2000 open-vent construction make necessary for lasting moisture control.
Cost: $5,000-$15,000 depending on size, condition, and required prep work.
Vapor Barrier Installation
20-mil reinforced polyethylene covers the ground and crawl space walls.
This prevents soil moisture from evaporating into the crawl space year-round.
Most effective when combined with vent sealing and mechanical dehumidification.
Crawl Space Dehumidifier Installation
A commercial-grade unit maintains humidity below 55% RH -- the threshold where mold and wood rot begin.
Cost: $1,200-$2,500 installed.
Required for code-compliant unvented crawl spaces per IRC R408.3.
Vent Sealing
Foundation vents are sealed when converting to a closed crawl space system.
A permit from Metro Nashville Codes Administration is required per IRC R408.3.
Crawl Space Mold Remediation
Existing mold is addressed before encapsulation begins.
Mold on floor joists or subfloor is treated and removed before the vapor barrier is installed.
Crawl Space Insulation
Insulation is installed on crawl space walls -- not subfloor joists -- in an encapsulated system.
Tennessee 2018 IECC Climate Zone 4 requires R-19 minimum for floors.
Closed-cell spray foam or rigid board on the walls is typical.
Sump Pump Installation
Required when standing water or groundwater intrusion is present before encapsulation can begin.
Cost: $1,000-$1,500 installed.
Free Crawl Space Inspection
Inspections are free throughout Nashville and Middle Tennessee.
A contractor assesses condition, identifies moisture sources, and provides a written estimate.
See our Nashville crawl space encapsulation cost guide.