Air Sealing and Duct Sealing in Charleston, SC
Seal the gaps and the ducts first: the cheapest big win on the list, and the move every good install starts with.
What air sealing (and duct sealing) involves.
Air sealing is the hunt for the gaps your envelope actually leaks through: top plates, wiring chases, recessed lights, attic hatches, band joists, and plumbing penetrations. We seal them with foam, caulk, and gaskets where the leaks are, not where it's easy.
Duct sealing is its own pass. Every joint in the attic and crawl gets mastic or a polymer sealant, boots get re-sealed, and returns get checked too, since leaky returns pull hot attic air straight into the system. Done together, the house stops exchanging air with its attic.
When to seal: before, with, or instead of foam.
Before foam, always. Foam is an investment in a sealed assembly, and sealing first keeps humid air from being pushed and pulled through cavities during the work. Any installer who skips it is building on a leaky frame.
With foam, the two come as one tight scope. Instead of foam: if a big spray job isn't in the budget this year, sealing plus new floor insulation is the honest alternative that still moves your bills. We'll say which fits when we've seen the house.
Why leaky ducts waste real money here.
A duct system in a Charleston attic loses cooling three ways at once: air pushed out of every unsealed joint, heat soaked through the duct jacket in a near-130-degree space, and extra load from leaky returns pulling that same heat into the system. The AC runs longer to cover all three.
Then there's the humidity side: cold ducts in damp attic air sweat, and that condensation drips onto insulation and drywall. Sealing stops the money leak and the wet one together.
What affects the quote.
Access comes first: an open attic with a clean duct run is a quick job, while tight chases and cluttered crawls are slower. Extent matters too, because a handful of major leaks costs less than a duct system that needs a full pass.
Bundling is the value move. Sealing added to a foam job rides on the same mobilization, so the incremental cost is small. Standalone sealing still pays for itself, just less dramatically.
Rebates: Dominion, Duke, and the paperwork.
Dominion Energy SC offers insulation and air-sealing rebates for residential electric customers, with amounts that vary by what you insulate and the R-value you reach; their ductwork rebate is separate. Duke Energy SC's approved-contractor path applies discounts on attic insulation upgrades at the contract level.
The paperwork is ours to steer. We help you file the utility rebate forms, and we'll tell you honestly which program you're in based on your address. The federal 25C credit wasn't extended past 2025, so utility programs, not federal dollars, are where the real money sits right now.
Ready for air + duct sealing in your house?
The free on-site assessment produces a written quote with a real number. Call the crew or send the form.
Straight answers
Air and duct sealing questions, answered.
Why air seal if I'm already adding insulation?
Because insulation slows heat but does nothing about air moving through gaps, and moving air carries the heat and the humidity. Seal the leaks first and the insulation you already own finally works the way its R-value says it should.
Do leaky attic ducts really waste that much cooling?
Often yes: a duct system in an unconditioned attic loses cooling from every joint, soaks heat through its jacket, and works against itself all summer. The AC runs longer to make up for it, and you feel it as long run times and rooms that never quite catch up.
Does Dominion or Duke pay me back for insulation or duct sealing?
Dominion SC pays insulation and air-sealing rebates to residential electric customers, with the ductwork rebate as its own program, and Duke SC applies attic insulation discounts through approved contractors. We help you file whichever program covers your address, and we confirm current amounts with the program pages before your install.
How long does air sealing take?
Most single homes are done in a day, whether it's an envelope pass only or that pass plus duct mastic. Bigger homes with heavy duct runs can take a second day. It's one of the smallest jobs on our list and often the first one worth doing.
Free quotes
Get your free on-site assessment.
Call (843) 439-8547 or send the form; the free assessment is the step that turns factors into a number.