Crawl Space Encapsulation & Insulation in Tallahassee, FL

Crawl space encapsulation and insulation means sealing the space under a house from outside air and ground moisture, then insulating it so the floor above stays comfortable. It suits the many older homes in Tallahassee, Quincy, Havana and Monticello that sit on piers or block foundations over a vented crawl space, and raised homes near the coast. Signs you need it: a musty or earthy smell inside, floors that feel damp or cupped, insulation batts hanging down or lying on the ground, rusty ductwork, or standing water after storms.

The humidity problem

Venting a crawl space sounds like a way to dry it out, but in a hot, humid climate it often does the opposite. Wikipedia's figures for Tallahassee show average relative humidity around 80% in July and about 59 inches of rain a year. When summer air drifts into the crawl space and meets floor framing and ducts cooled by the air conditioning above, moisture condenses. Fiberglass batts between the joists soak it up, get heavy and fall. Wood stays damp, which invites mold and wood-destroying insects.

What encapsulation involves

A typical job includes a heavy plastic vapor barrier over the ground, run up the foundation walls and taped at the seams; the foundation vents sealed shut; the access door sealed and insulated; and a plan for keeping the air dry, usually a small amount of conditioned air or a dehumidifier. Then the insulation goes on the walls, often closed-cell spray foam, which handles damp conditions and seals the rim at the same time. Old, wet batts come out first.

Insulating the floor instead

Some crawl spaces are better left vented, for example on homes in flood zones, where the floor must stay open below, or where a sealed crawl space is not practical. Then we insulate the underside of the floor, usually with closed-cell foam sprayed against the subfloor, which seals air and does not hold water. The Department of Energy suggests R-13 for an uninsulated floor in Zone 2.

Termites and inspection access

The 2023 Florida Building Code, Residential (Section R318.8) limits foam plastic on the exterior face or underside of foundation walls in very heavy termite areas, and R318.7 keeps a six-inch gap between grade and exterior wall coverings so termites can be seen. Inside a crawl space, we leave a strip at the top of the wall or a gap at the sill plate where your pest control company needs to see. Talk to your termite provider before encapsulating, since some bond contracts have their own rules.

Water first, then the barrier

If water runs into the crawl space after rain, an encapsulation will not fix that alone. Gutters, downspouts and grading often need attention first, and some crawl spaces need a drain or sump. We tell you what we see and what should come first. Get a free estimate