Spray foam insulation in Hanahan SC - an attic sealed tight and kept dry

Spray foam in the Charleston area usually costs about $2,000 to $4,500 to cover a 1,000-square-foot area with 3 inches of foam. Open cell sits toward the low end of that range and closed cell toward the top, so the foam type is one of the biggest things that moves your price. That's the going rate around here, not a quote, and my written estimate gives you the number for your own attic.

Choose closed cell foam if you want the foam itself to handle vapor control, because open cell insulates but lets moisture vapor pass through, while closed cell, the denser foam, insulates and blocks vapor too. Closed cell also sits at the top of the price range above, so the choice comes down to how your attic will stay dry and what you want to spend.

A sealed attic is worth considering when it holds your ducts or equipment, will become living space, or is hard to vent or seal any other way. That's national building guidance, and if none of those fit your house, the cheaper route of sealing gaps and topping up usually makes more sense. The same guidance finds unvented attics hold up better in hurricanes, mostly because their soffits, the undersides of the roof overhang, are built sturdier.

Plan to be out of the house for at least 24 hours, and come back only after the foam has cured and the house has been aired out and cleaned. We settle your re-entry time, the point when it's safe to come back, with you before the job starts so you can line up a place to stay for the kids and pets. If anyone at home has asthma, respiratory allergies, a skin condition or has reacted to foam chemicals before, read the foam maker's product information carefully first.

A sealed attic needs a planned way to get moisture out, and that goes in the estimate so you price it along with the foam. Because the attic is sealed, any furnace or water heater up there that burns fuel should be a direct-vent, sealed-combustion unit that vents outdoors, which is worth checking before the foam goes in.

In South Carolina, this work falls under the state's insulation installers class, which covers installing, altering and repairing insulation for temperature or sound control. The state also counts anyone a homeowner hires for skilled trade work over $500 as a residential specialty contractor, and foam sprayed on the outside of a roof falls outside the insulation class altogether. We're fully licensed and insured. Satisfaction guaranteed.