Duct Sealing With Aeroseal: Costs & Results

Your ductwork is probably leaking 20 to 30 percent of the air your HVAC system works so hard to heat and cool — into the attic, the crawlspace, and inside your walls. Traditional duct sealing means a technician crawling through tight spaces with mastic and tape, fixing only the leaks they can reach. Aeroseal takes a different approach: it pressurizes the duct system with a fog of sealant particles that find and plug leaks from the inside, including the ones no human could ever reach. Here's what the technology actually does, what it costs in 2026, and how to tell if your ducts are candidates.

The Leak Problem Nobody Sees

Duct leakage is the most underappreciated efficiency problem in American homes. The Department of Energy has long estimated that the typical duct system loses 25-30% of conditioned air to leaks, and field studies keep confirming it. That means for every dollar you spend heating or cooling, a quarter of it is conditioning your attic.

The symptoms are familiar: rooms that never quite reach temperature, a system that runs constantly on extreme days, dust streaks around supply registers, and energy bills that seem high for the home's size and equipment age. Homeowners usually blame the furnace or the air conditioner — and sometimes they're right — but leaky ducts make even brand-new high-efficiency equipment perform like a mid-grade unit from twenty years ago.

Leaks happen at every joint, seam, and connection in the duct system: where branch ducts meet the trunk, where the trunk meets the plenum, at register boots, and anywhere ducts were cut and reconnected during renovations. In attics and crawlspaces, the problem compounds — leaked air is lost to unconditioned space, and the negative pressure pulls dusty, humid outside air back into the system through the same gaps.

A professional duct leakage test (a duct-blaster test, usually $250-$450 as a standalone diagnostic) quantifies the problem in CFM of leakage at 25 pascals of pressure. As a rule of thumb, leakage above 15-20% of system airflow is worth fixing aggressively; below 10%, the returns diminish. Get the test before you commit to any sealing method — it's the only way to measure results afterward, and any contractor who proposes sealing without measuring first is guessing.

How Aeroseal Works: Sealant Fog, Guided by Physics

Aeroseal is an aerosol duct-sealing process, and the concept is elegantly simple. The technician blocks all the registers and grilles, connects a machine to the duct system, and pressurizes it. Then the machine injects a fog of tiny sealant particles — a water-based vinyl acetate polymer — into the airstream. The particles follow the air exactly the way leaking air does: they stream toward every crack, gap, and hole. Where air escapes through a leak, particles accumulate on the leak's edges, building up layer by layer until the gap is bridged and sealed. Leaks up to about 5/8 of an inch get sealed; the process ignores everything else because particles only accumulate where air is moving through an opening.

The process is computer-controlled and continuously measured. The machine tracks leakage in real time, so you get a before-and-after leakage number on a printed report — typically showing 80-95% leakage reduction. A residential job takes 4-8 hours including setup, sealing, and verification. Occupants usually stay in the home; the sealant is non-toxic once cured, and the system is ventilated before the registers are reopened.

What Aeroseal doesn't do matters too. It doesn't seal disconnected ducts — if a branch has fallen off the trunk entirely, no fog will fix it; that needs a technician with sheet metal and mastic first. It doesn't fix crushed or kinked flex duct, undersized returns, or poor system design. And it seals from the inside, so it can't address insulation that's fallen off the outside of ducts. A competent provider inspects first and tells you which problems are Aeroseal problems and which aren't.

The technology has been around since the 1990s (developed with DOE support) and has sealed millions of feet of ductwork. It's not experimental — but it is a specialty service, so provider quality varies more than the technology does.

Aeroseal vs. Manual Sealing: An Honest Comparison

Manual duct sealing — mastic, tape, and a technician in the attic — is still the right answer in many situations. Here's how to choose:

Choose Aeroseal when: ducts run through inaccessible spaces (inside walls, between floors, buried in insulation), the leakage test shows many small leaks distributed throughout the system, or the home's layout makes manual access impractical or dangerous. Aeroseal's superpower is reaching the unreachable — the leaks behind drywall and under floors that manual sealing can never touch.

Choose manual sealing when: the inspection finds disconnected ducts, crushed flex runs, or missing insulation — all mechanical problems that need hands and materials. Manual sealing is also the right first step when leakage is concentrated in a few large, accessible gaps that a technician can fix in an afternoon.

Choose both when: the system has mechanical problems and distributed small leaks — which describes a large fraction of older homes. The standard professional sequence is manual repair first (reconnect, straighten, insulate), then Aeroseal to finish the leaks that remain. Many Aeroseal providers do both in one visit.

On results: both methods, done well, achieve similar leakage reductions on the leaks they can reach. The difference is coverage. Manual sealing fixes what the technician can see and touch; Aeroseal fixes everything the air touches. For ducts hidden in finished spaces, there's genuinely no manual alternative.

A note on "duct cleaning" upsells: sealing and cleaning are different services solving different problems. Sealing fixes leakage; cleaning removes accumulated dust. Be wary of providers who insist you need both without showing you test results or photos that justify each one.

Measured Outcomes: What the Numbers Actually Show

The before-and-after leakage report is Aeroseal's strongest feature: you get a measured result, not a promise. Typical residential outcomes show leakage dropping from 20-35% of system airflow to under 5% — a reduction of 80-95%. Those are duct-blaster numbers, measured the same way before and after, and they're consistent across independent field studies.

What does that translate to in comfort and bills? Field data and utility program evaluations generally show:

• Energy savings of 10-25% on heating and cooling costs, depending on how leaky the ducts were, where they're located (attic ducts waste more than basement ducts), and the local climate.
• Noticeably more even temperatures between rooms, because supply air actually reaches the registers instead of leaking out along the way.
• Shorter equipment runtimes on extreme days — the system satisfies the thermostat faster because it's not fighting its own losses.
• Better humidity control in cooling season, since the system runs proper cycles instead of struggling, and less humid attic air is drawn into returns.

Be skeptical of anyone promising specific dollar savings without seeing your bills, your climate, and your leakage test. The range above is honest; your home's position in it depends on the details. A home with 35% leakage in attic ducts in Phoenix saves far more than a home with 12% leakage in basement ducts in Seattle.

One more measured outcome worth mentioning: indoor air quality. Sealed ducts pull less dust, insulation fiber, and crawlspace air into the airstream. Homeowners with allergies often report improvement — not because Aeroseal filters anything, but because it stops the system from inhaling the attic.

2026 Costs, Rebates, and the Payback Math

Aeroseal pricing in 2026 typically runs $1,800-$3,500 for a single residential HVAC system, with most homes landing around $2,200-$2,800. Larger homes with two systems, complex duct layouts, or significant pre-repair work run $3,500-$5,500. The price generally includes the pre-sealing inspection, the leakage test, the sealing process itself, and the certified before-and-after report.

Manual duct sealing for comparison runs $1,000-$2,500 for accessible systems — cheaper when the leaks are reachable, impossible to price when they're not. The combined approach (manual repairs plus Aeroseal) typically adds $500-$1,500 to the Aeroseal price for the mechanical fixes.

Rebates meaningfully change the math. Many utilities offer duct-sealing rebates of $200-$600, and some utility weatherization programs cover Aeroseal entirely for qualifying homes. The federal 25C energy-efficient home improvement credit has covered duct sealing in recent years — check current IRS guidance for 2026, as credit details change. Your provider should know the local rebate landscape; if they don't, that's a yellow flag about their professionalism.

Payback: at 10-25% HVAC energy savings, a $2,500 job in a home spending $2,400/year on heating and cooling pays back in roughly 4-8 years on energy alone — faster in extreme climates, with expensive energy, or where rebates apply. But the payback framing undersells it: comfort improvement is immediate, equipment lifespan extends when runtimes drop, and the measured report gives you documentation that adds credibility at resale time.

Costs are 2026 US market ranges; get itemized local quotes. Get at least two quotes, and make sure each includes the leakage test — a provider who prices without measuring is selling a process, not a result.

Hiring Right: Vetting an Aeroseal Provider

Aeroseal is a licensed process — providers are trained and certified — but certification is a floor, not a guarantee. Here's how to vet:

• Demand the leakage test first. A real provider measures before quoting. If the test shows under 10% leakage, an honest provider tells you the returns are marginal.
• Ask about pre-repairs. "What do you do when you find disconnected ducts?" The right answer involves fixing them manually before sealing, with separate pricing.
• Ask for the report format. You should receive a computer-generated before-and-after leakage report. Ask to see a sample from a past job.
• Check what they seal around. The process requires blocking registers and protecting the equipment — ask how they isolate the furnace/air handler and the coil from sealant fog.
• Get the warranty in writing. Reputable providers warranty the seal for 10 years; some offer longer. Know what it covers and what voids it (like later duct modifications).
• Verify insurance and licensing. They're working on your HVAC system — confirm HVAC licensing and liability insurance, not just the Aeroseal certification.

Red flags: quotes without measurement, pressure to decide on the spot, bundling with unrequested services, and any claim that Aeroseal eliminates the need for a properly sized and maintained HVAC system. Sealing makes a good system perform as designed; it doesn't rescue a failing compressor or an undersized furnace.

Finally, schedule strategically. Aeroseal can be done any time of year, but shoulder seasons (spring and fall) are ideal — you're not depending on the system daily, scheduling is easier, and you can verify comfort improvements before the next extreme season arrives. Pair it with a professional system tune-up and you've given your HVAC its best possible operating conditions for the years ahead.

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