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 typically costs $280-$680 for most homes, with full-system sealing running $1,200-$2,400 depending on access and the condition of the original ductwork. Our crews serve Fairfax daily from our Washington, DC scheduling office, and we carry the equipment to handle both the sheet-metal trunk lines common in 1970s colonials and the flex-duct retrofits found in split-levels from Kings Park to Greenbriar. Call (240) 771-1508 for a written estimate before any work begins.
We’ve been in enough Fairfax crawl spaces to know the patterns. The 1960s-1990s federal-boom subdivisions that dominate this market, Mantua and Kings Park especially, hold original ductwork that was never designed for fifty years of continuous May-through-September cooling. Our Duct Repair & Sealing crews document every run with before-and-after photography, and every price is written and agreed before a panel comes off.
Why CleanRun Air Duct Cleaning Ashburn Is Fairfax’s Preferred Duct Repair & Sealing Company
CleanRun has served Fairfax since 2013 under the H.A.V.E.N. Standard, with 52,000+ homes documented and every job starting with a written price. Our reputation here is built on what we can show, not what we claim. Fairfax customers receive the same deliverable every time: a written scope, a written price under Haven Standard Clause 1, and a photo record of every duct run before and after work.
Our crews know the local housing stock. We’ve sealed metal trunks in Greenbriar ramblers, replaced crushed flex in Mantua crawl spaces, and reinsulated runs over Difficult Run tributaries where moisture drives biological growth at the seams. This isn’t generalized experience. It’s repeated fieldwork in the same neighborhoods, the same construction eras, the same failure modes.
Calls are answered by a live person, 24/7, and technicians are background-checked, uniformed, and identified by name before arrival under Haven Standard Clause 3: Verified Crews. Our 365-Day Done Right Promise applies to every Fairfax job in writing, not as a verbal courtesy.
We also offer a Free Second Opinion on any written estimate. Bring a competitor’s quote; we put our number next to it in writing.
Our Duct Repair & Sealing Services in Fairfax
Duct Sealing
Air leakage from supply and return ducts is the single biggest efficiency loss in Fairfax’s older homes. We seal with mastic compound and metal-backed tape at every joint, collar, and plenum connection. In the 1960s and 1970s colonials around Mantua, we regularly find original seams that were never sealed beyond a friction fit, bleeding conditioned air into wall cavities and crawl spaces for decades. Our sealing work is photographed, and the leakage reduction is measurable.
Flex Duct Repair
Flex duct is common in Fairfax additions, retrofits, and crawl-space runs from the 1980s and 1990s. It crushes, sags, and pulls off collars. In a 1968 colonial off the Mantua loop, our tech climbed into the crawl space over a Difficult Run tributary and found a sagging flex run pulled clean off its collar, feeding conditioned air into the joists while the back bedroom ran hot. We ran a camera inspection, reset and mastic-sealed the connection, then wrapped the repaired run in new insulation before a full source removal of the system. The supply and return ducts stopped whistling and the room held temp for the first time in years. Flex duct repair in Fairfax typically runs $180-$340 per run.
Metal Duct Repair
The galvanized steel trunk lines in Fairfax’s original 1960s-1970s systems corrode at seams, separate at hangers, and develop whistle-inducing gaps where vibration has worked joints loose. We repair with matching gauge metal, rehang with proper supports, and seal with mastic. Metal duct repair in Fairfax homes typically costs $240-$480 per section, depending on access and the extent of corrosion.
Duct Insulation
Uninsulated or degraded duct insulation is a major issue in Fairfax crawl spaces and attics, particularly along the creek corridors where moisture is chronic. We install new fiberglass or closed-cell insulation wraps, sealed with vapor barriers, to maintain supply air temperature from the plenum to the register. Duct insulation in Fairfax typically runs $4-$7 per linear foot, with most homes needing 80-150 feet of coverage.
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
Our equipment roster includes Rotobrush for mechanical agitation, Abatement Technologies for negative-pressure containment, and Aprilaire for filtration and humidity control components. We stock common repair parts for Fairfax’s dominant HVAC brands, and our crews carry mastic, insulation wraps, and collar fittings on every truck. That means most Fairfax repairs are completed in a single visit, with no waiting on parts orders.
Common Duct Repair & Sealing Problems We See in Fairfax Homes
- Delaminating fiberglass duct liner in Mantua and Kings Park colonials. The original internal liner installed in the 1960s and 1970s is now crumbling after 50+ years of thermal cycling. Our cameras show friable fragments shedding into the airstream, a failure mode that almost never appears in newer Loudoun County builds just 20 miles west.
- Flex duct sags and disconnects in creek-corridor crawl spaces. Homes over Pohick Creek, Difficult Run, and Bull Run tributaries experience chronic moisture that weakens flex duct supports and drives biological growth at seams. The duct doesn’t just leak, it physically separates from its collar.
- Crushed or kinked runs from decades of unrecorded prior use. Fairfax’s transient federal-contractor and military population means most home sales include no duct maintenance history. Crushed runs from storage, renovation, or pest activity go undiagnosed through years of uninterrupted AC operation.
- Return-air leakage pulling unfiltered attic and crawl-space air. In split-levels from Kings Park to Greenbriar, we find return plenums with gaping seams or missing panels, pressurizing attics with conditioned air while pulling fiberglass, dust, and pollen into the system.
Pricing for Duct Repair & Sealing in Fairfax, VA
Most Fairfax homeowners pay between $280 and $680 for targeted duct repair and sealing, with full-system sealing ranging from $1,200 to $2,400. Here’s how typical jobs break down:
- Single flex duct repair/replacement: $180-$340
- Metal duct section repair: $240-$480
- Mastic sealing of accessible joints (per system): $280-$550
- Duct insulation replacement: $4-$7 per linear foot
- Full system sealing with photo documentation: $1,200-$2,400
What moves the price: access difficulty (crawl space vs. basement), the number of disconnected or crushed runs, and whether the original fiberglass liner requires full replacement rather than spot repair. Every Fairfax job starts with a camera inspection, a written scope, and a written price under Haven Standard Clause 1. No per-vent pricing. No coupon bait. Call (240) 771-1508 for a free estimate with exact numbers for your home.
We Also Serve Cities Near Fairfax
Our crews work daily across Northern Virginia. We also provide Duct Repair & Sealing in Fairfax and surrounding communities including Burke, Vienna, Annandale, and Chantilly. Scheduling is coordinated from our Washington, DC office with local dispatch to your 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
The first sign is visible debris at registers: gray or brown fibrous material collecting on vanes or blowing into rooms when the system cycles. We confirm with a camera inspection of the supply and return trunks. If the internal fiberglass liner is delaminating, we document the extent and provide a written scope for liner replacement or full duct remediation. Call (240) 771-1508 to schedule a camera inspection.
In Kings Park split-levels, we most often find a disconnected, crushed, or uninsulated flex run serving that room, sometimes buried in a crawl space where sagging has pulled the duct off its collar. The system runs continuously but delivers no conditioned air to the register. We camera-locate the break, repair or replace the run, seal with mastic, and reinsulate. Most Kings Park bedroom fixes run $180-$340. Call (240) 771-1508 for a written estimate.
Yes. Northern Virginia ranks among the worst mid-Atlantic metros for spring tree pollen, with oak and tulip poplar peaking April through May. Saturated return-air intakes pull that load directly into duct systems, where it combines with dust and moisture to form matting at elbows and transitions. Sealed, intact ductwork contains this buildup at the filter; leaky returns pull pollen past the filter into the trunk lines. We document this accumulation during camera inspections and remove it with source extraction before sealing the system.
We start with a full camera inspection of every accessible duct run, documented with photography. In Fairfax’s 1960-1995 housing stock, we expect to find disconnected flex, delaminating liner, or unsealed metal seams. You receive the photo record, a written findings report, and a written price for any recommended repair before work begins. No surprises. Call (240) 771-1508 to book a new-homeowner inspection.
Sealing alone won’t hold if the flex is undersized, overstretched, or improperly supported. We reset the run with proper tension, secure it with a mechanical clamp and mastic sealant, then add support straps to prevent future sag. In moisture-prone Fairfax crawl spaces, we also wrap the repair in new insulation with a vapor barrier. The combination of mechanical support and sealed insulation prevents the recurrence that simple tape cannot. Call (240) 771-1508 for a crawl-space inspection and written repair scope.
Ready to see what’s actually inside your ducts? Call (240) 771-1508 for a free estimate. Every Fairfax job includes a written price before work starts, a Documented Photo Record of every run, and our 365-Day Done Right Promise in writing.
Written by Tomas Reyes, Owner at CleanRun Duct Repair & Cleaning, serving Fairfax since 2013.