Insulation Guides for South Carolina Homes

Spray foam insulation in South Carolina typically costs $1.00–$1.60 per board foot for open-cell foam and $1.60–$2.60 per board foot for closed-cell foam. Attic and crawl-space scopes are quoted from measured board feet after an on-site evaluation. Final pricing depends on crawl-space access, the foam thickness the assembly needs, and whether existing insulation has to be removed first — we give a firm number after we see the space.

Closed-cell spray foam delivers approximately R-6 to R-7 per inch; open-cell approximately R-3.5 to R-4 per inch. Closed-cell is recommended for South Carolina crawl spaces and moisture-prone areas because it provides a Class II vapor retarder — critical in a hot, humid climate. Open-cell is preferred for many attic applications and costs less per board foot. The Greenville / Upstate SC service area sits in IECC Climate Zone 3A (mixed-humid). Code requires R-38 to R-49 (Zone 3A).

Spray foam is a permanent insulation with an expected lifespan of 80+ years without sagging or compressing when properly installed. Unlike fiberglass batts, it does not compress, sag, or absorb moisture. In South Carolina's hot, humid climate, closed-cell foam also resists the moisture infiltration that shortens the life of other insulation types.

Homeowners typically see 20–40% lower heating and cooling costs after air sealing and insulation, depending on the home's starting condition. In South Carolina's cooling-dominated climate, spray foam's dual function as insulation and air barrier stops the humid-air infiltration and radiant heat that fiberglass batts alone cannot address.

Duke Energy (Progress) and local programs periodically offer rebates for qualifying insulation and air-sealing upgrades; amounts vary by measure and change annually — confirm current amounts before your estimate. The federal 25C Energy Efficient Home Improvement Credit for insulation expired December 31, 2025 and is not currently available. We do not advertise it as an active incentive.