Duct Repair & Sealing Cost - We Measure the Leak Before We Quote

Every visit starts with

Whole-system duct and dryer vent check with before-and-after photos - you see exactly what came out of your vents

Worth knowing

That "$99 whole-house special" is a bait ad - the real number appears once they are in your hallway, or the "clean" is a shop-vac at the register. We photograph the inside of your ducts before and after instead.

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Before & after – our own jobs

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How Much Does Duct Repair & Sealing Cost in Ashburn?

Our Duct Repair & Sealing services in Ashburn, VA typically cost between $350 and $1,200 for a standard single-family home, with most jobs landing in the $450-$750 range depending on the number of duct runs affected, the severity of the damage, and the access conditions in your attic or crawl space. Aeroseal or mastic sealant applied to a full system – including supply and return trunks – runs closer to $800-$1,800 for larger homes above 2,500 square feet. At CleanRun, every price is written and delivered before any work starts, so the number you see here is the same kind of number you’ll see on your quote.

Duct Repair & Sealing Cost Breakdown (2026)

The table below reflects actual pricing ranges in the Ashburn market as of 2026. These are not national averages pulled from a database – they reflect what homeowners in Loudoun County are paying for this work right now, including the material costs, labor rates, and access conditions typical to the townhome developments near Route 7 and the larger colonials in Broadlands and Brambleton.

What Pushes the Price Up

Access is the biggest single variable. A two-story colonial in Broadlands with duct runs buried in a tight attic with blown insulation over the top of every flex duct collar takes significantly longer to work safely than a split-level in Ashburn Farm where the trunk lines run exposed through a dry basement. More time means more labor, and labor is the majority of the cost on most duct jobs.

The second driver is scope discovered during the inspection. A camera pass through the duct system – the same photographic inspection CleanRun runs on every visit as a standard deliverable – sometimes shows problems that weren’t visible from the register: a flex duct section kinked at 90 degrees and cutting airflow by more than half, or a supply run that separated at the plenum connection and has been pushing conditioned air into the attic since the home was built. Photographing every duct run before quoting means the written price reflects what’s actually there, not what’s assumed.

What Keeps the Price Down

Catching duct leaks early – before they compound into insulation contamination or HVAC strain – usually means less scope and a lower invoice. A duct run that has a loose collar at the boot can be sealed in 20 minutes with mastic compound. The same run ignored for five years may need the flex section replaced entirely. In Ashburn, where attic temperatures routinely hit 130°F in July and August, UV and heat degradation of flex duct jacket material accelerates faster than it does in more temperate markets – which is a real local reason to catch problems at the seal stage rather than the replacement stage.

Combining duct sealing with a scheduled CleanRun air duct cleaning visit also reduces the overall cost per service, because the access work – pulling registers, setting up negative-pressure extraction – is already done. Running both services in one mobilization is almost always less expensive than scheduling them separately.

What Affects Duct Repair & Sealing Pricing in Ashburn

• Home size and duct count: A 1,600 square foot townhome in Ashburn Village has roughly 8-12 duct runs. A 3,800 square foot single-family home in Brambleton may have 20 or more. Pricing scales with the number of runs that need inspection, sealing, or repair – not with square footage as an abstract number.
• Duct material type: Flex duct – the silver-jacketed corrugated tubing used in most Ashburn homes built after 1990 – is less expensive to seal and replace than rigid sheet metal trunk lines. However, flex duct is also more likely to be kinked, torn, or improperly supported in tight attic spaces, which increases scope at discovery.
• Access and attic conditions: Ashburn attics vary widely. Homes in One Loudoun and newer Brambleton phases often have well-framed attic access with decent clearance. Older Ashburn Farm properties sometimes have low-pitch rooflines with insulation packed tight around every run. Confined-space access adds labor time and affects the quote.
• Leakage severity – confirmed by pressure testing: A leakage test using a Duct Blaster instrument (a calibrated fan that pressurizes the duct system and measures air loss as a percentage of total system flow) tells us whether you have a 5% leakage problem or a 30% leakage problem. Those two numbers produce very different repair scopes and very different prices. Skipping the test and guessing is not something CleanRun does – a written price has to be based on a documented condition.
• Sealing method – mastic vs. Aeroseal vs. foil tape: Mastic sealant (a thick, paste-based compound applied with a brush) is the most durable exterior sealing method and is typically used on accessible joints and collar connections. Aeroseal is a pressurized polymer process that seals from the inside of the duct, reaching leaks in inaccessible locations – it costs more per job but covers the leaks mastic cannot physically reach. Foil-backed tape, when applied correctly over a cleaned surface, is appropriate for minor sealing tasks. The method used affects material cost and process time.
• Permit requirements under Loudoun County code: Most duct repair and sealing work in Ashburn does not require a separate mechanical permit. However, if the scope includes replacing a supply trunk section connected to the air handler or modifying the plenum, Loudoun County Building and Development may require a permit under the Virginia Uniform Statewide Building Code. The written quote will identify any permit requirement before work starts – that requirement is never a surprise disclosed mid-job.

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Ashburn-Specific Duct Conditions Worth Knowing

Ashburn’s development history creates a very specific pattern of duct problems. The majority of single-family homes in Ashburn were built between 1992 and 2010, in subdivisions like Ashburn Farm, Ashburn Village, Belmont Country Club, Broadlands, and Brambleton. Those homes share a common construction era that used flex duct extensively, often with installation shortcuts that weren’t visible at the time of the original inspection: flex duct supported too loosely so it sags and restricts airflow, collars secured with only a single layer of tape that has since failed, and return plenums that were framed into the wall cavity rather than built from sealed metal – a practice that essentially turned the wall cavity itself into a leaking return.

In Ashburn’s newer communities – particularly One Loudoun and the Moorefield Station area – the homes are built to tighter energy codes under Virginia’s adoption of IECC 2015 and 2018 standards, which require duct leakage testing at time of construction. Those homes tend to have better baseline sealing, but they are also getting to the age (built 2013-2020) where first-time duct inspections are appropriate and where any construction defects are now showing up in energy bills and uneven room temperatures.

We also see a specific pattern in Ashburn during home sale transactions: buyers who had a general home inspection done discover HVAC notes that mention “ductwork not fully inspected” – because general inspectors don’t put cameras in duct runs. That’s a reasonable time to schedule a proper camera inspection and get a documented baseline on what’s actually in the system.

How to Save on Duct Repair & Sealing in Ashburn

Get a leakage test before agreeing to any scope

A Duct Blaster test costs $150-$300 and gives you a measured number: your system is losing X% of conditioned air before it reaches the rooms it’s supposed to serve. That number tells you whether sealing the whole system makes financial sense – or whether a targeted repair on two or three identified problem runs is the right answer. Agreeing to a full system seal without a measured baseline is buying an outcome you can’t verify.

Combine duct sealing with your cleaning visit

If your system is due for a cleaning, scheduling Duct Repair & Sealing in Ashburn at the same time as the cleaning visit reduces the total cost of both services. The access work, equipment setup, and technician time are shared across both scopes – and you leave with a documented photo record of both the interior condition and the seal condition in a single deliverable.

Bring in a second opinion before signing a large repair estimate

CleanRun offers a Free Second Opinion on any written estimate – bring in a competitor’s quote and we’ll put our own number next to it in writing. That’s not a promotional offer with an expiration date; it’s a standing practice under the Haven Standard. If you’ve received a quote for $2,000 worth of duct work and want to know whether that scope is real, call us at (240) 771-1508 and we’ll tell you what we see when we put a camera in the system.

Don’t defer a small problem into a large one

A single disconnected flex duct collar costs $85-$175 to seal. Left open in an Ashburn attic for two or three summers, it introduces humidity and particulates into the duct system, degrades surrounding flex duct material through moisture cycling, and can contribute to mold conditions inside the duct run. The repair bill for that sequence of events is not $175 anymore. Ashburn’s climate – hot, humid summers and cold winters with frequent freeze-thaw cycling in January and February – accelerates degradation in ways that a temperate climate does not.

Ask for the written price upfront, every time

Haven Standard Clause 1 means CleanRun does not dispatch a technician and then present a price. The written price is delivered before any work starts – no exceptions. If a contractor’s process involves sending someone out to “take a look” and then building a number on the spot with pressure to decide immediately, that’s not a process built around your interests. The written price, in advance, is the baseline expectation – and it makes comparison shopping straightforward.

FAQs – Duct Repair & Sealing Cost in Ashburn

How much does duct sealing cost for a typical Ashburn home?

For a standard single-family home in Ashburn – roughly 2,000-2,800 square feet, with flex duct runs in the attic – duct sealing typically costs $450-$900 for a partial-to-full mastic seal of the supply and return system. Homes in that size range in Broadlands, Brambleton, or Ashburn Farm with reasonably accessible attic conditions tend to land in the middle of that range. Larger homes or those requiring Aeroseal (pressurized internal polymer sealing) run $1,100-$1,800. Every CleanRun quote is written and delivered before work begins, so you’ll know the exact number before anyone touches the system. Call (240) 771-1508 to schedule a written estimate.

Is it worth repairing ducts or replacing them entirely?

Repair is worth it when the duct runs are structurally sound but leaking at the joints – which describes the majority of Ashburn homes built between 1992 and 2010. Full replacement makes sense when the flex duct jacket is degraded beyond the point where sealing holds, when the inner liner has collapsed or torn across multiple sections, or when the duct layout itself is causing airflow problems that sealing won’t fix. A Duct Blaster pressure test plus a camera inspection of each run gives you the documented evidence to make that call with a number attached, not a guess. In most Ashburn homes we inspect, repair and sealing is the right answer – replacement is the right answer in roughly 20-30% of cases where the flex duct material itself has deteriorated.

Can duct sealing actually lower my energy bills in Ashburn?

Yes – and the magnitude depends on how much you’re currently losing. The U.S. Department of Energy estimates that leaky duct systems in typical American homes lose 20-30% of conditioned air before it reaches the living space. In Ashburn, where Dominion Energy bills spike in July and August as systems run continuously against 95°F heat and 70% humidity, a duct system losing 25% of its output is adding measurably to that bill. Sealing a system from 25% leakage to 5% or below (the ENERGY STAR standard for new construction) does not eliminate your HVAC bill, but it means the system delivers what it’s producing. The payback period on sealing work depends on the cost of the job and your current utility spend – something we can walk through during the estimate call at (240) 771-1508.

How long does duct sealing last?

Mastic sealant applied correctly to clean, dry duct surfaces lasts 15-20 years or longer – it cures to a hard, flexible compound that doesn’t dry out or crack under normal thermal cycling. Foil-backed tape, applied to a properly prepared surface, typically holds for 10-15 years. Aeroseal’s pressurized polymer has been tested to hold for over 40 years under normal HVAC operating conditions, according to manufacturer testing data from Aeroseal LLC. All of those numbers assume the duct runs aren’t physically disturbed – if a contractor or renovator cuts into the ductwork later, the seals at that junction need to be redone. The 365-Day Done Right Promise covers the sealing work CleanRun performs: if a seal we applied fails within 365 days, we make it right – in writing, not subject to a manager’s discretion.

What’s the difference between duct sealing and duct cleaning – do I need both?

Duct cleaning removes the debris, dust, and particulate buildup from the interior surfaces of the duct runs – using negative-pressure extraction equipment (a high-powered vacuum system that creates suction from the trunk while agitation tools, including Rotobrush rotating brushes, dislodge material from the duct walls). Duct sealing closes the gaps, separations, and leaks in the duct joints and connections so conditioned air doesn’t escape. They solve different problems. A leaky duct system that gets cleaned is still leaky. A sealed duct system full of debris is still moving contaminated air. In homes where both conditions are present – and in Ashburn homes built in the 1990s, that’s common – the standard sequence is cleaning first, then sealing, because mastic sealant adheres better to a clean surface than a dusty one. Scheduling them together in one visit is the most cost-efficient approach.

How CleanRun Prices Duct Repair in Ashburn

Every CleanRun visit starts the same way: a camera inspection of each duct run, photographed before anyone touches anything. The images are part of the job record – not a sales tool, not a scare tactic, just documentation of what the camera found at the time the crew arrived. The written price follows from that inspection. That’s Haven Standard Clause 1: the price is in writing before work starts. No verbal estimates, no “we’ll figure it out once we’re in the attic.”

The technicians on every Ashburn job are background-checked, uniformed, and identified by name before arrival – Haven Standard Clause 3. They use professional-grade equipment: Rotobrush for agitation, Nikro and Abatement Technologies extraction systems for negative-pressure cleaning, and mastic compound, Aeroseal, or Guardsman-grade foil tape for sealing, depending on what the inspection shows. Customers can look up every brand name on that list independently before agreeing to a price.

When the job is done, the same duct runs get photographed again. The before-and-after photo record goes to the customer as a standard deliverable – not something you have to ask for, not a PDF attached to a follow-up email three days later. It leaves with the crew on the day of the job. That practice has been part of every CleanRun job since the company’s first service call in 2013, and it’s the reason the 365-Day Done Right Promise has teeth: if something isn’t right, there’s a documented record of exactly what was done and what it looked like when the crew left.

CleanRun has served more than 52,000 homes with this process – written price, documented photo record, no exceptions. Tomas Reyes built that standard into the company from the beginning, and it applies to every Ashburn job the same way it applied to the first one.

Ready for a Written Price on Your Ashburn Duct System?

If you’re trying to understand what duct repair or sealing will actually cost for your specific home in Ashburn, the most useful next step is a camera inspection and a written quote – not an estimate over the phone based on square footage alone. Call CleanRun at (240) 771-1508. A live person answers every call, and the written price comes before any work starts – that’s not a policy, it’s how we operate. If you already have a competitor’s written quote, bring it: we’ll put our number next to it at no cost.

Pricing reflects the Ashburn, VA market as of 2026. CleanRun Air Duct Cleaning Ashburn offers free estimates – call (240) 771-1508.

Written by Tomas Reyes, Owner at CleanRun Air Duct Cleaning Ashburn, serving Ashburn, VA since 2013.