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 Rockville
Duct repair and sealing in Rockville, MD typically runs $340-$890 for most residential jobs, with full-system sealing on older homes reaching the higher end when crawl-space moisture damage is involved. Our crews are scheduled from the Washington, DC office and serve Rockville properties directly, carrying the equipment and materials needed to seal sheet-metal, flex, and hybrid systems without a return trip. Call (571) 526-0015 and a live person will answer, 24/7, to book a free written estimate.
We’ve worked enough Rockville homes to know the difference between a King Farm townhouse built in 2005 and a Twinbrook rambler from 1953. The ductwork tells the story before we open the first panel. That local knowledge changes what we bring, what we expect to find, and how we price the job.
Why CleanRun Air Duct Cleaning Fairfax Is Rockville’s Preferred Duct Repair & Sealing Company
Our Duct Repair & Sealing team has served Montgomery County since 2013, with over 52,000 homes documented in our photo records. Rockville customers specifically mention the before-and-after images in their reviews - the ability to see inside their own ducts rather than take a technician’s word for it.
We answer calls live, schedule Rockville appointments with realistic drive-time built in, and send background-checked, uniformed technicians who are identified by name before arrival. Haven Standard Clause 3: Verified Crews. No subcontractor roulette.
The 365-Day Done Right Promise applies to every Rockville job in writing, not as a verbal assurance that disappears with the crew. If the seal fails or the moisture problem returns, we make it right. That promise is backed by the full H.A.V.E.N. Standard, and it’s why we publish our license number on every page rather than burying it in a footer.
We also offer a Free Second Opinion on any written estimate from another company. Bring your quote. We’ll put our number next to it, itemized, before any work starts.
Our Duct Repair & Sealing Services in Rockville
Mastic Sealant Application
Mastic sealant is a water-based paste brushed onto duct joints and seams, then cured to a flexible, airtight finish - unlike tape, it won’t dry out and peel in Rockville’s humid summer crawl spaces. In Twinbrook homes with original sheet-metal trunks, we apply mastic to every longitudinal seam and transverse joint after source removal, because new mastic on dirty metal traps debris and fails early. The mastic we use is rated for the temperature swings seen in unconditioned Montgomery County crawl spaces, from winter lows below freezing to summer highs over 95°F.
Flex Duct Repair
Flex duct - the insulated flexible tubing common in retrofits and some original 1970s construction - collapses, tears, or disconnects at collars over time. In Rockville’s Hungerford corridor split-levels, we regularly find original flex connections from the 1960s and 70s that have pulled apart at the plenum (the main distribution box), dumping conditioned air into the attic or crawl space. We replace damaged flex runs with new R-8 insulated duct, secure with mechanical fasteners and mastic, and photograph every connection before closing the access.
Metal Duct Repair
Sheet-metal ductwork in Rockville’s older homes often suffers from seam separation, corrosion at low points where condensation pools, and physical damage from decades of maintenance work in tight crawl spaces. Twinbrook’s 1950s systems are particularly prone to corrosion where the original galvanized coating has degraded in moist crawl environments. We cut out damaged sections, fabricate replacement pieces on site, and seal with mastic and mechanical fasteners - not tape alone. Every repair is pressure-tested before we leave.
Duct Insulation Replacement
Insulation on ducts in unconditioned spaces degrades, compresses, or becomes mold-contaminated - especially in Rockville’s vented crawl spaces where ground moisture is present. We remove compromised insulation, treat the duct surface if mold is present, and re-wrap with new fiberglass or closed-cell insulation depending on the application. In Twinbrook homes with no vapor barrier, we document the moisture source and recommend crawl-space encapsulation partners so the insulation investment isn’t wasted.
Air Leak Repair
Air leaks in duct systems waste 20-30% of conditioned air on average, but in Rockville’s older homes with wood-heat supplementation and return ducts pulling from dusty environments, the penalty is higher - the system works harder to move air it already conditioned. We pressurize the system, locate leaks with smoke or theatrical fog, then seal with mastic or replace damaged sections. The repair is verified with a post-seal pressure test, and the results are included in your documented photo record.
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 Rockville
Our equipment roster includes Rotobrush agitation systems, Abatement Technologies negative-air machines, and Guardsman sealants and insulation products - brands you can look up independently before agreeing to any work. We stock common duct repair materials locally for Rockville jobs, so most repairs are completed in a single visit without waiting on parts. For specialized components in older systems, our DC-area warehouse carries hard-to-find sheet-metal fittings and transition pieces that match 1950s-era dimensions.
Common Duct Repair & Sealing Problems We See in Rockville Homes
- Twinbrook crawl-space moisture infiltration. Original-era sheet-metal ducts routed through vented crawl spaces with no vapor barrier pull ground moisture directly into the system. We’ve opened ducts in Twinbrook homes where the interior surface was coated with active mold growth the homeowner had no idea existed - no musty smell at the registers, because the leak was downstream of the living space.
- Wood-heat soot loading in return ducts. Rockville properties with wood stoves or pellet heaters draw combustion particulates into return-air systems, especially when the stove is the primary heat source and the HVAC fan runs continuously. The loading is heavier than standard calculations assume, and cleaning intervals need to be shorter - we base our recommendations on what the camera shows, not the calendar.
- Unpaved access road dust infiltration. Homes on or near open land, farm lanes, and unpaved drives in the Twinbrook and eastern Rockville areas pull measurable dust through return-air pathways, even with standard filtration. The dust accumulates at elbows and transitions, creating restriction points that strain the air handler and raise energy bills.
- Garden apartment trunk-line deterioration. The 1970s-80s complexes along Rockville Pike share HVAC trunk lines that are often 15-20 years past recommended service intervals. Leaks in these common systems affect multiple units, and property managers need documented photo records to justify capital repairs to ownership.
Pricing for Duct Repair & Sealing in Rockville, MD
A typical duct sealing job in Rockville runs $340-$620 for a single-system home with accessible ductwork. Full-system sealing on Twinbrook-era homes with crawl-space moisture damage and multiple repair points ranges $680-$890. Flex duct replacement is priced per run, with most residential jobs falling between $180-$340 per replaced section including insulation and mastic seal.
What moves the price: accessibility (crawl space vs. basement), extent of moisture or mold damage, number of separate repairs needed, and whether the system requires negative-pressure containment for safe work. We deliver a written price before any work starts, every time, under Haven Standard Clause 1. No per-vent pricing. No teaser rates that balloon once the truck is in your drive.
Call (571) 526-0015 for a free written estimate. We’ll inspect your system, photograph what we find, and give you a documented price you can compare against any other quote - including our Free Second Opinion if you already have one in hand.
We Also Serve Cities Near Rockville
Our crews work throughout Montgomery County, including Duct Repair & Sealing in Rockville and neighboring Gaithersburg and Silver Spring. Scheduling is coordinated from our Washington, DC office with route efficiency built in - we don’t book a Rockville morning and a Gaithersburg afternoon on the same day, so your appointment window is realistic.
Serving Rockville, MD - Our Local Coverage Area
We’re based in the Rockville 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 Rockville
Every 2-3 years, not the standard 5-year interval, because wood-heat soot and unpaved-road dust load the system faster than suburban homes with gas heat and paved access. We set the next service based on what the camera shows at the current visit - if the return trunk already shows 1/4-inch buildup at year two, we don’t wait for year five. Call (571) 526-0015 and we’ll inspect your system and give you a realistic interval based on your actual conditions.
Twinbrook’s 1950s sheet-metal ducts were installed in vented crawl spaces with no vapor barrier, a construction detail that lets ground moisture migrate directly into the duct runs and grow mold behind any seal that doesn’t address the source. King Farm and Fallsgrove homes built from the 1990s onward use conditioned or sealed crawl spaces, or basement-mounted systems, and don’t face the same moisture loading. A seal job in Twinbrook that ignores the crawl-space environment traps mold behind fresh mastic and fails within a season.
Yes, if the metal is structurally sound - no active corrosion through the wall, no physical damage beyond repairable seam separation. We clean the interior with negative-pressure extraction and mechanical agitation, repair separated seams with fabricated patches and mastic, then re-insulate the exterior. If the camera shows corrosion pinholes or structural failure at multiple points, we’ll document that and quote replacement sections. The decision is always based on photographed evidence, not a sales pitch.
We arrive at the scheduled window, identify ourselves by name, and begin with a visual inspection of accessible ductwork and the air handler. Then we run a camera through every duct run we can access, photographing the interior condition. We show you the images, explain what we found in plain language, and deliver a written price before any repair work starts. Once approved, we set up containment if needed, complete the repairs, pressure-test the system, and deliver a documented photo record of every run - before and after - as part of the standard job record. The entire process typically takes 3-5 hours for a single-system home.
Yes - shared HVAC trunk lines in 1970s-80s garden apartment complexes serve multiple units through common ducts that individual tenants can’t access, and leaks in these systems create pressure imbalances that draw unconditioned air and odors between units. Property managers need documented photo records of trunk-line condition to justify capital repairs, and repairs require coordination with building maintenance to shut down shared equipment. We work with Rockville property managers on these projects, delivering the documentation their ownership groups require for repair approvals.
Written by Tomas Reyes, Owner at CleanRun Air Duct Cleaning Fairfax, serving Rockville since 2013.