Crawl space insulation in Charleston, SC
Old fiberglass batts between floor joists often sag and soak up moisture in Lowcountry crawl spaces. Pros typically remove wet insulation and, in a sealed crawl space, insulate the foundation walls with moisture-tolerant rigid foam or spray foam instead.
What it costs
| Item | Published range | Source |
|---|---|---|
| Crawl space insulation, total | $500–$3,700 | HomeGuide, How Much Does Crawl Space Encapsulation Cost? (Jan 14, 2026) |
| Closed-cell spray foam, walls | $2.00–$5.00 per sq ft | HomeGuide, How Much Does Crawl Space Encapsulation Cost? (Jan 14, 2026) |
| Rigid foam board | $1.20–$3.70 per sq ft | HomeGuide, How Much Does Crawl Space Encapsulation Cost? (Jan 14, 2026) |
| Removing old insulation | $1–$2 per sq ft | HomeGuide, How Much Does Crawl Space Encapsulation Cost? (Jan 14, 2026) |
Crawl space insulation FAQ
Should insulation go under the floor or on the walls?
In a vented crawl space it's usually under the floor. In a sealed, encapsulated crawl space it's usually on the foundation walls. A pro should explain which fits your plan.
Why is my old insulation falling down?
Fiberglass that absorbs moisture gets heavy and sags. Falling insulation is a common sign of a humidity problem.
Where we can match you
Crawl space insulation requests are accepted across the Charleston area:
Downtown CharlestonWest AshleyJames IslandJohns IslandMount PleasantDaniel IslandNorth CharlestonSummervilleGoose CreekHanahanLadsonMoncks CornerIsle of PalmsFolly BeachKiawah IslandSullivan's Island
Related services
Crawl space encapsulationSeal the crawl space with a heavy liner, closed vents and controlled humidity.Vapor barrier installationReplace torn or thin plastic with a sealed ground barrier.Crawl space repairSagging floors, rotted joists, beams and sill plates.Crawl space dehumidifiersA sized dehumidifier to keep humidity in check year-round.Drainage & sump pumpsFor crawl spaces that hold water after rain.Crawl space mold remediationClean and treat mold before sealing the space.
Referral service disclosure. Charleston Crawl Space Quotes is not a contractor. We pass your request to an independent local pro who may pay us a referral fee if you hire them. That never costs you anything extra, and you are never obligated to hire anyone. Full disclosure.