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 Fairfax
Duct repair and sealing in Fairfax, VA typically costs $280-$650 for most residential jobs, with flex duct replacement in attic runs running toward the higher end and single-point mastic sealing toward the lower. We’re usually scheduling Fairfax appointments within 3-5 business days, and every visit starts with a written price before any panel comes off. Crews dispatch from our Washington, DC office and carry the full equipment roster - Rotobrush, Nikro, Abatement Technologies, and Guardsman materials - so we don’t waste a trip back to the shop.
Fairfax isn’t a generic suburb to us. We’ve worked the split-levels off Braddock Road, the colonials in Mantua, the raised-ranches threading through Greenbriar. We know which neighborhoods have the original 1980s flex duct still sagging through attics that hit 130°F in July. That local familiarity means we show up with the right materials and don’t spend your first hour figuring out what you’re working with.
Call (240) 363-3380 to schedule. Estimates are free, and the price we write is the price you pay.
Why CleanRun Air Duct Cleaning Washington Is Fairfax’s Preferred Duct Repair & Sealing Company
We’ve served Fairfax homeowners since adding the county to our route schedule in our early years, and the pattern is consistent: residents here research before they call. They want credentials they can verify, prices in writing, and proof the work happened. That’s exactly what our Duct Repair & Sealing team delivers.
Our Fairfax customers tend to find us after a bad experience with a coupon service - the $79 special that turned into $800, or the crew that ran a shop vac for twenty minutes and called it done. We answer differently. Haven Standard Clause 1 requires a written price before work starts. Clause 4 requires a Documented Photo Record of every duct run, delivered to you before we leave. Our technicians are background-checked, uniformed, and identified by name before arrival - Haven Standard Clause 3: Verified Crews. No exceptions.
The 365-Day Done Right Promise applies to every Fairfax job. If the seal fails, the joint separates, or the repair doesn’t hold, we make it right. In writing. Not subject to manager mood.
Our Duct Repair & Sealing Services in Fairfax
Flex Duct Repair
Fairfax’s 1970s-1990s buildout left thousands of homes with flex duct that has now exceeded its 25-year manufacturer lifespan. In neighborhoods like Mantua and the Burke corridor, we regularly find flex duct liners cracked and corrugated from years in 130°F attics, joints separated by thermal expansion cycles, and sagging runs that collect condensation and debris. Our flex duct repair replaces damaged sections with new insulated flex, reconnects separated joints using mechanical fasteners and Guardsman flex repair tape, and restores proper slope and support. Every repair is photographed before and after, and the new run is sealed with mastic to prevent leakage at connection points.
Mastic Sealant Application
Air leaks at duct joints and plenum connections can waste 20-30% of conditioned air before it reaches your registers. In Fairfax’s humid climate, those leaks also pull unconditioned attic or basement air into your system, along with the pollen and mold spores that thrive here. We apply professional-grade mastic sealant - a thick, fiber-reinforced compound that remains flexible after curing - to all accessible joints, seams, and penetrations. Unlike foil tape, which degrades in temperature swings, mastic holds through Fairfax’s summer attic extremes and winter freeze cycles. We photograph every sealed joint for your job record.
Air Leak Repair
Some leaks are obvious: a disconnected return duct dumping air into a crawl space, a supply register boot pulled away from the floor joist. Others require pressure testing or camera inspection to locate. In Fairfax’s older homes, we frequently find leaks caused by ductwork settling on Virginia clay soils, vibration from blower motors running against undersized returns, and previous DIY repairs that used the wrong materials. Our air leak repair identifies the source, fixes it with appropriate methods - mechanical reconnection, saddle tap replacement, or section replacement - and verifies the fix with a post-repair pressure differential check when indicated.
Duct Insulation
Uninsulated or degraded duct insulation in Fairfax attics creates two problems: thermal loss that drives up energy bills, and condensation that breeds mold. We replace damaged insulation with foil-faced fiberglass wrap or closed-cell foam insulation, depending on the application and accessibility. In Fairfax’s 1980s colonials with attic-mounted air handlers, proper insulation is often the difference between a system that maintains setpoint and one that runs continuously without catching up.
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 Fairfax
We stock repair materials from Honeywell, Aprilaire, and Guardsman - brands with published specifications customers can verify independently. For Fairfax jobs, that means no waiting for parts orders on standard repairs. Honeywell dampers and zone controls integrate with existing Fairfax HVAC systems. Aprilaire media cabinets and filter housings replace deteriorating original equipment in 1990s builds. Guardsman flex repair tape and mastic compounds meet SMACNA sealing standards for residential ductwork. Our equipment roster also includes Rotobrush mechanical agitation systems, Nikro HEPA-filtered negative-pressure extractors, and Abatement Technologies containment gear - all named so you can look up what we’re using before you agree to a price.
Common Duct Repair & Sealing Problems We See in Fairfax Homes
- Joint separation in attic-run flex duct. The 130°F+ temperatures in Fairfax’s unvented attics crack flex-duct liners and loosen clamped joints. We find separated sections leaking conditioned air directly into the attic, a failure mode rare in Loudoun County’s newer slab-on-grade builds with basement mechanical rooms.
- Shared dryer vent stacks in condos and apartments. Fairfax’s multi-unit buildings often route dryer exhaust through a common vertical stack. Lint accumulates through the full height, creating fire hazards individual owners can’t address alone. We clean and seal these stacks with proper access fittings and document the full pathway.
- Duct-board deterioration in damp basements. Fairfax homes on Virginia clay frequently have basement humidity issues. Original fiberglass duct-board absorbs moisture, sheds particles into the airstream, and degrades air handler components. We replace deteriorated duct-board with metal or new insulated flex, sealed at all connections.
- Collapsed flex duct from physical damage. Storage in attics, rodent activity, and decades of compression from walking paths leave Fairfax flex duct flattened or torn. These sections restrict airflow, increase static pressure, and cause blower motors to short-cycle - the exact pattern we found in the Mantua raised-ranch.
Pricing for Duct Repair & Sealing in Fairfax, VA
Here’s what duct repair and sealing costs in the Fairfax market:
| Service | Typical Range |
|---|---|
| Single-point mastic sealing (accessible joint) | $180-$280 |
| Flex duct section replacement (per 25 ft. run) | $340-$520 |
| Metal duct repair / reconnection | $280-$450 |
| Full duct-board plenum replacement | $650-$950 |
| Duct insulation replacement (per run) | $220-$380 |
| Comprehensive system sealing with pressure test | $480-$780 |
Attic access difficulty, extent of contamination, and whether we need to coordinate with your HVAC contractor for refrigerant recovery affect the final price. We deliver that price in writing before work starts - Haven Standard Clause 1 - and include the Documented Photo Record as standard. No per-vent pricing, no teaser coupons, no invoice inflation once the van is in your driveway.
Call (240) 363-3380 for your exact quote. Estimates are free.
We Also Serve Cities Near Fairfax
Our crews work Duct Repair & Sealing in Fairfax and the surrounding Northern Virginia corridor, including Reston, Falls Church, Springfield, and Herndon. Scheduling is coordinated from our Washington, DC office, with local technicians dispatched to each area.
Serving Fairfax, VA - Our Local Coverage Area
We’re based in the Fairfax 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 Fairfax
No. Shared dryer vent stacks require building-wide access and coordination with property management or the HOA. We can inspect your unit’s connection point, replace the flex transition duct behind your dryer, and install a proper lint trap, but the vertical stack itself must be addressed as a common element. We document our findings with photos you can present to your building manager, and we offer written estimates for full-stack cleaning and sealing when the association authorizes the work. Call (240) 363-3380 to schedule a unit-level inspection.
Three signs point to repair needs: rooms that won’t maintain temperature despite adequate airflow at the register, blower motors that short-cycle or run continuously, and visible flex duct sagging or disconnected at attic access points. We recently serviced a raised-ranch home in Mantua with a second-floor bedroom that never cooled properly. Our tech ran a camera inspection and found a separated flex-duct joint in the 140°F attic, leaking conditioned air into the unconditioned space. Using mastic sealant and Guardsman flex repair tape, we reconnected and sealed the run, then performed source removal on the supply and return ducts with negative pressure and HEPA filtration. The room finally held temperature, and the blower motor stopped short-cycling. Camera inspection separates cleaning candidates from repair candidates - we offer this as part of our standard assessment. Call (240) 363-3380 to book.
Yes. Sealed ducts prevent the infiltration of unconditioned, pollen-laden, humidity-saturated air that Fairfax’s climate produces in abundance. Unsealed return leaks in attics pull 130°F air and oak pollen directly into your system; supply leaks dump conditioned air you’ll pay to replace. The Department of Energy estimates typical duct leakage at 20-30% of total airflow - in Fairfax’s climate, that translates to higher humidity indoors, heavier allergen loads, and equipment that works harder for shorter lifespan. Mastic sealing pays for itself in reduced energy use and reduced filter loading. Call (240) 363-3380 for a pressure-test assessment and written price.
We use Guardsman flex repair tape and mastic compounds, Honeywell dampers and zone controls, and Aprilaire filtration and media cabinet components on Fairfax jobs. Our cleaning and extraction equipment includes Rotobrush mechanical agitation systems, Nikro HEPA-filtered negative-pressure extractors, and Abatement Technologies containment gear. Every brand is named so you can verify specifications independently before agreeing to a price. We do not use unbranded or consumer-grade materials for duct repairs. Call (240) 363-3380 if you have questions about materials for your specific system.
Fairfax’s 1970s-1990s housing stock was built with flex duct and duct-board materials now 30-50 years old, well past manufacturer lifespan, and routed through unconditioned attics that exceed 130°F in summer. That thermal stress cracks liners and separates joints. Loudoun County’s newer builds use metal ductwork in conditioned basements or mechanical closets - fundamentally different construction with different failure modes. Combined with Fairfax’s heavier pollen burden and higher humidity, aging duct infrastructure here creates indoor air quality problems that newer markets simply don’t face at the same scale. Delaying repair means continued energy waste, equipment strain, and allergen circulation. Call (240) 363-3380 for a free assessment.
Ready to fix your ductwork? Call (240) 363-3380 or schedule online. We’ll deliver a written price before any work starts, complete the repair with documented before-and-after photos of every run, and back it with our 365-Day Done Right Promise. Haven Standard. Since 2013.
Written by Tomas Reyes, Owner at CleanRun Duct Repair & Cleaning, serving Fairfax and Northern Virginia since 2013.