Whole-system duct and dryer vent check with before-and-after photos - you see exactly what came out of your vents
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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AfterFast, Reliable Duct Repair & Sealing Across Herndon
Duct repair and sealing in Herndon, VA typically costs $280-$680 for most townhome systems, with full duct board replacement running $1,200-$2,400 when the original 1980s liner has failed. We complete most sealing and repair jobs in a single scheduled visit, and every project starts with a written price before any panel comes off. Call (571) 520-6317 for a free estimate with exact numbers for your home.
We’ve worked in Herndon’s dense townhome clusters since 2013 - the communities off Elden Street, along the Herndon Parkway corridor, and throughout the planned developments that make up most of the residential base here. Our crews are familiar with the restricted parking, shared-wall access issues, and HOA scheduling requirements that come with the territory. Dispatch and scheduling are coordinated from our Washington, DC office, but the technicians who arrive at your door live and work in this market. They know that a standard rigid brush system won’t fit through the party-wall chases in a 1989 three-story townhome, and they bring the flexible-shaft equipment that actually reaches the branch runs.
Why CleanRun Air Duct Cleaning Herndon Is Herndon’s Preferred Duct Repair & Sealing Company
Herndon homeowners research before they call. We built our business around that fact.
Our reputation here rests on documentation, not claims. Every job since 2013 - more than 52,000 homes - has started with a written price delivered before work begins, and ended with a Documented Photo Record of every duct run, before and after. Customers in Herndon receive those photos as a standard deliverable, not an upsell. The 365-Day Done Right Promise applies to every repair and sealing job we perform in Loudoun and Fairfax counties, backed in writing on the scope sheet, not buried in website copy.
Haven Standard Clause 3: Verified Crews means our technicians are background-checked, uniformed, and identified by name before arrival. No exceptions. The license number is published on this page, not hidden in a footer, because we expect customers to verify it.
We also offer a Free Second Opinion on any written estimate from a competitor. Bring us the quote. We’ll put our number next to it, item by item, in writing.
Our Duct Repair & Sealing Services in Herndon
Duct Sealing
Sealing in Herndon means addressing mastic that has cracked under twenty years of Northern Virginia humidity cycles, especially at joints and registers where duct board meets metal transitions. We apply professional-grade mastic sealant and, where appropriate, aerosol-based duct sealing for systems with access limitations. In the tight chase configurations common off Elden Street, we often find that the original seals failed years ago and the homeowner has been heating and cooling the wall cavity instead of the living space. A typical duct sealing job in Herndon runs $280-$450 for a townhome system.
Flex Duct Repair
Flex duct in Herndon’s attic spaces degrades faster than expected because those attics hit extreme temperatures in summer, and the Dulles-area precipitation belt pushes humidity higher than DC proper. We replace collapsed, torn, or kinked flex duct with properly sized runs, supported at code-required intervals, and sealed with mastic at every connection. In townhome clusters where multiple units share attic plenum space, we coordinate access with property management when needed. Flex duct repair in Herndon typically falls between $180-$340 per run.
Metal Duct Repair
Where Herndon homes have sheet metal trunk lines - often in basement or garage configurations - we repair separated seams, replace rusted sections, and restore proper damper function. Metal duct lasts longer than duct board but suffers at the transition points, especially where previous contractors have used tape instead of mastic. We photograph every seam before touching it, so you see what failed and why. Metal duct repair in Herndon generally ranges from $220-$520 depending on accessibility and extent.
Duct Insulation
Uninsulated or degraded duct insulation in Herndon attics and crawlspaces creates condensation problems that accelerate mold growth, particularly on the aging fiberglass duct board that dominates the local housing stock. We install new insulation to current standards, vapor-sealed at joints, with particular attention to the supply plenum where temperature differentials are greatest. This work is often combined with sealing for systems that have multiple failure modes.
What happens when you call
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A real person answersNo phone trees - you reach a local pro.
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You get an upfront price rangeHonest numbers before anyone is dispatched.
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A background-checked tech heads outLicensed & insured, dispatched right away.
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You approve before work beginsNothing starts until you say go.
BeforeAfterTrusted Brands We Service in Herndon
Our equipment roster includes Rotobrush flexible-shaft systems for the restricted-access branch runs common in Herndon townhomes, Nikro negative-pressure extractors for contained debris removal, and Abatement Technologies HEPA filtration for occupied-space protection. We stock mastic, mechanical fasteners, and transition fittings sized for the duct board dimensions used in 1980s-1990s construction, which reduces return trips and keeps jobs on schedule. These are trade-recognized brands customers can look up independently - we name them because we expect you to verify what you’re paying for.
Common Duct Repair & Sealing Problems We See in Herndon Homes
- Crumbled duct board liner shedding fibers into supply air. The fiberglass duct board installed in Herndon’s 1978-1995 townhomes has exceeded its 25-year service life. We regularly find the liner disintegrating at the first elbow, sending glass fibers through registers and into living spaces. This isn’t a cleaning issue - it’s a repair-or-replace decision, and we document it with photos before recommending either path.
- Branch runs in shared party-wall chases left untouched by previous cleaners. Standard rigid equipment cannot navigate the tight turns in these chases. Technicians without flexible-shaft systems clean only the visible trunk lines and leave the branch runs full of debris. Mold odor returns within months. We bring Rotobrush flexible-shaft equipment specifically for this geometry.
- Condensation-driven mold growth on duct board surfaces. Northern Virginia’s humid subtropical summers push attic and crawlspace humidity to extremes. Where mastic seals have cracked at joints, warm moist air contacts cool duct surfaces and grows mold far more aggressively on porous duct board than on metal. Sealing the system is often the critical step that makes cleaning results last.
- Dryer vents shared through multi-unit stacks in condo and townhome buildings. Herndon’s dense 1980s construction often routes dryer exhaust through vertical stacks serving multiple units. A partial blockage in one unit’s connection pressurizes the entire stack, forcing lint into neighboring ducts and creating fire hazards that individual unit cleaning cannot address. We inspect the full stack configuration and coordinate with HOA or property management for common-area repairs.
Pricing for Duct Repair & Sealing in Herndon, VA
| Service | Typical Range in Herndon |
|---|---|
| Duct sealing (whole system, townhome) | $280-$450 |
| Flex duct repair (per run) | $180-$340 |
| Metal duct repair (seam/section) | $220-$520 |
| Duct board replacement (partial) | $650-$1,100 |
| Full duct board replacement (townhome system) | $1,200-$2,400 |
| Dryer vent stack inspection/cleaning (multi-unit) | $180-$320 |
These are whole-system prices, not per-vent teaser rates that balloon once the truck arrives. Every estimate is written and agreed before work starts - Haven Standard Clause 1. Factors that move Herndon jobs within these ranges: accessibility of attic or crawlspace, extent of duct board degradation, whether previous repairs used improper materials, and coordination requirements with HOA or neighboring units in shared-wall buildings.
We do not quote over the phone without seeing the system. We do provide free written estimates, typically scheduled within 48 hours. Call (571) 520-6317.
We Also Serve Cities Near Herndon
Our crews work throughout Loudoun and Fairfax counties, including Herndon‘s immediate neighbors: Reston to the east, Sterling to the northwest, Chantilly to the south, and Fairfax to the southeast. The same written-price protocol, documented photo record, and 365-Day Done Right Promise apply in every service area. If you’re in one of these communities and found this page while researching, the same technical realities - aging duct board, shared-wall chases, humid summer conditions - likely apply to your home as well.
Serving Herndon, VA - Our Local Coverage Area
We’re based in the Herndon area and know this community well. Use the map below to see our service coverage - if you’re nearby, we can almost certainly help.
FAQs - Duct Repair & Sealing in Herndon
Your Herndon home was likely built during the 1980s-1990s Dulles Technology Corridor boom, when fiberglass duct board was the standard HVAC construction method. That duct board has now aged 30-45 years, past its serviceable life, and is far more susceptible to mold growth in Northern Virginia’s humid summers than the metal ductwork used in newer suburbs like Ashburn or South Riding. The porous surface of degraded duct board traps moisture and provides a growth medium that smooth metal simply doesn’t. Call (571) 520-6317 and we’ll inspect your system to determine whether repair, sealing, or replacement is the appropriate path.
Yes - we bring flexible-shaft brush systems specifically for this geometry, which is common in the townhome clusters off Elden Street and around the Herndon Parkway corridor. Standard rigid equipment cannot navigate these chases, which is why previous cleaners may have left your branch runs untouched. Our Duct Repair & Sealing crew photographs every run before and after, so you can verify what was actually reached. Call (571) 520-6317 to schedule an inspection.
We assess this during our pre-work inspection, which is included in every estimate. Key indicators: visible fiber shedding at register openings, musty odor that returns within weeks of cleaning, crumbled material at duct joints, and previous cleaning reports that note “limited access to branch runs.” We photograph these conditions and present the evidence before recommending any work. Replacement is necessary when the liner has degraded to the point that cleaning would release more fibers than it removes. Call (571) 520-6317 for a free inspection with written findings.
Herndon’s dense 1980s construction often routes dryer exhaust through vertical stacks serving multiple units. A partial blockage in one connection pressurizes the entire stack, forcing lint into neighboring ducts and creating fire hazards that individual unit cleaning cannot fully address. We inspect the full stack configuration and, where common-area repairs are needed, document our findings for HOA or property management coordination. This is a safety issue specific to Herndon’s housing stock and shared building systems. Call (571) 520-6317 to schedule a stack inspection.
A typical sealing job for a Herndon townhome takes 3-4 hours and addresses every accessible joint, register boot, and transition point with mastic sealant or aerosol-based sealing where geometry requires it. We pressurize the system afterward to verify leakage reduction. Most Herndon homeowners see improved airflow at distant registers - upstairs bedrooms in these two- and three-story units are the most common complaint - and reduced runtime on their HVAC equipment because conditioned air is no longer escaping into wall cavities. The work is photographed before and after, and backed by our 365-Day Done Right Promise. Call (571) 520-6317 for a written estimate.
Written by Tomas Reyes, Owner at CleanRun Duct Repair & Cleaning, serving Herndon since 2013.