Fast, Reliable Duct Repair & Sealing Across Seattle
Duct repair and sealing in Seattle typically costs $280-$650 for most residential jobs, with flex duct replacement running higher and simple mastic re-sealing toward the lower end. Most repairs are completed in a single visit, and our Duct Repair & Sealing team carries the sealants, insulation, and replacement flex duct needed to finish the job that day.
We’ve worked in Seattle homes since 2012, from the original Craftsman bungalows of Capitol Hill to the mid-century ramblers climbing Beacon Hill’s slopes. Seattle’s damp marine climate and retrofitted ductwork create problems you won’t find in drier markets, and we’ve built our repair methods around them. When you call (833) 700-5198, you’ll reach a live person at our office, 24 hours a day. We’ll give you an upfront price before we lift a single tool, and we back every job with our 90-Day Done Right Promise in writing.
Why Bellows Air Duct & Vent Co. of Seattle Is Seattle’s Preferred Duct Repair & Sealing Company
Forty-two years in this trade means we’ve crawled through more Seattle crawl spaces than we can count. We’ve sealed leaky metal joints in Ballard basements, replaced crushed flex duct in Rainier Valley, and pulled rodent-damaged runs from Seward Park homes where the original oil furnace left behind a tangle of incompatible fittings. That history matters when your technician recognizes your home’s duct configuration before they even open the access panel.
Seattle homeowners have left us reviews for decades. They mention the camera inspection we show before and after work, the uniformed technician who arrived on time, and the price that matched the phone quote exactly. Our background-checked crews answer to a live dispatcher, not an app or voicemail tree, and most repairs finish in one visit because our trucks carry Rotobrush and Nikro equipment plus the sealants and replacement duct stock that Seattle’s older housing stock demands.
We’re not the cheapest option in town. We’re the one you don’t have to call back.
Our Duct Repair & Sealing Services in Seattle
Duct Sealing
Seattle’s retrofitted duct systems leak more air than purpose-built installations, and the leaks are rarely where you’d expect. In Capitol Hill bungalows, we find original metal joints where mastic sealant has degraded after decades of damp crawl-space exposure. Our crews pressurize the system, locate every leak with a smoke pencil or thermal camera, then re-seal with fresh mastic or foil-backed tape rated for Pacific Northwest humidity. A typical duct sealing job in Seattle runs $280-$420 for a single system, and most homeowners see measurable improvement in room-to-room airflow within hours.
Flex Duct Repair
Flex duct collapses under its own weight when insulation becomes waterlogged, and Seattle’s unencapsulated crawl spaces provide plenty of moisture. We recently sealed the flex-duct splices in a 1920s Craftsman on Beacon Hill where the original oil-to-gas-converted system had collected both mold and mouse nesting in the same run. After HEPA-containment cleanup, we applied mastic and insulation to the exposed joints in the crawl space, preventing further moisture intrusion and improving airflow by 30%. Flex duct replacement in Seattle typically runs $340-$580 per run, depending on crawl-space accessibility.
Metal Duct Repair
Galvanized steel ductwork in Seattle’s pre-WWII homes rusts from the outside in when crawl-space moisture condenses on cold metal. We patch small rust-throughs with galvanized sheet and seal the repair, but we’re direct with homeowners when a section is too far gone. Metal duct repair in Seattle runs $180-$320 for localized patching, while full section replacement climbs to $450-$680. We’ll show you the camera footage and explain which path makes sense for your system and budget.
Mastic Sealant Application
Standard duct tape fails in Seattle’s humidity. We use water-based mastic sealants formulated for damp environments, applied with brushes and spatulas to ensure complete joint coverage. In Ballard ramblers and Columbia City foursquares, we often find original sealant that has turned to powder after years of moisture cycling. Re-application typically costs $220-$380 for a full system and lasts substantially longer than tape in our climate.
Duct Insulation
Uninsulated or degraded duct insulation in Seattle crawl spaces creates condensation that drips onto joists and attracts mold. We replace waterlogged insulation with fiberglass wrap or closed-cell foam where appropriate, sealing the vapor barrier at every seam. Insulation replacement runs $260-$480 depending on linear footage and whether we need to remove contaminated material first.
What happens when you call
- 1
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.
Trusted Brands We Service in Seattle
Our trucks stock sealants, tapes, and replacement components from Abatement Technologies, Rotobrush, and Nikro, the same brands serious HVAC contractors specify for commercial installations. We don’t order parts from a warehouse across the country and make you wait. For Seattle homeowners, that means we can often complete a flex duct repair or full mastic re-sealing without a return trip. We also source insulation and vapor-barrier materials sized for the irregular runs common in Seattle’s retrofitted systems, not just standard new-construction dimensions.
Common Duct Repair & Sealing Problems We See in Seattle Homes
- Collapsed flex duct in uninsulated crawl spaces - Moisture weight and rodent activity crush flex duct from the inside, common in Rainier Valley and Seward Park homes where retrofitted runs sag between joists. We replace the damaged section and add support straps rated for damp conditions.
- Leaky metal duct joints in retrofitted Capitol Hill systems - Mastic sealant degrades quickly in persistent dampness, and original installations often used tape that failed decades ago. We clean the joint to bare metal and re-seal with fresh mastic rated for marine humidity.
- Mold colonies inside supply runs never dried by central AC - Seattle’s historically heat-only homes never ran a cooling cycle to dehumidify duct interiors. We treat affected runs with biocide, then re-insulate to prevent recurrence, especially in Ballard ramblers with crawl-space supply lines.
- Flex-duct connections pulling apart at crawl-space penetrations - The combination of oil-to-gas conversion hardware and decades of vibration loosens connections where flex meets metal. We secure with mechanical fasteners and seal with mastic, not tape that will fail again.
Pricing for Duct Repair & Sealing in Seattle, WA
| Service | Typical Range in Seattle |
|---|---|
| Duct sealing (mastic re-application, full system) | $280-$420 |
| Flex duct repair/replacement (per run) | $340-$580 |
| Metal duct patching (localized) | $180-$320 |
| Metal duct section replacement | $450-$680 |
| Mastic sealant application (joints only) | $220-$380 |
| Duct insulation replacement | $260-$480 |
These ranges reflect what we charge Seattle homeowners for standard access conditions. Crawl spaces under 18 inches, extensive contamination requiring HEPA containment, or multiple system zones will add labor time. We disclose the full price before work begins, and we honor our standing offers: $50 off any repair over $250, free second opinion on any written estimate, and a permanent 5% senior and veteran discount. Call (833) 700-5198 for a free estimate with no obligation.
We Also Serve Cities Near Seattle
Our crews roll daily from our Seattle base to Seattle neighborhoods and surrounding communities including White Center, Mercer Island, Bellevue, and Kirkland. The same upfront pricing, camera inspection, and 90-Day Done Right Promise apply whether we’re working on a Mercer Island waterfront home or a White Center rambler.
Serving Seattle, WA - Our Local Coverage Area
We’re based in the Seattle 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 Seattle
Seattle’s dominant housing stock was built before central forced-air existed, so ductwork was retrofitted later through crawl spaces and attics with more joints, splices, and irregular runs than purpose-built systems. The original oil-to-gas conversions in neighborhoods like Beacon Hill and Columbia City added incompatible fittings that loosen over decades of vibration and moisture cycling. If your home was built before 1970 and has retrofitted ductwork, we almost always find more leaks than a comparable new build. Call (833) 700-5198 and we’ll show you on camera exactly where your system is losing air.
Yes, but only if the sealing is paired with thorough cleaning of the contamination already inside. The Puget Sound basin’s topography traps Eastern Washington and Cascade wildfire smoke for days, and fine particulate matter embeds deep in duct systems. Sealing prevents new infiltration from crawl spaces and attic bypasses, but existing PM2.5 must be mechanically removed. We seal after cleaning, not instead of it. For a full assessment of smoke contamination in your Seattle home, call (833) 700-5198 for a free estimate.
Water-based mastic sealant outperforms foil tape and duct tape in Seattle’s persistent dampness. We apply it with brushes to ensure complete joint coverage, then allow proper cure time before pressurizing the system. In crawl spaces with standing moisture or vapor intrusion, we may recommend encapsulation or dehumidification in addition to sealing. The right sealant for your specific conditions is part of our upfront assessment. Call (833) 700-5198 to schedule.
Localized rust and small leaks are worth patching if the remaining metal is sound. We replace sections when rust has penetrated through, when original fittings are incompatible with modern equipment, or when repair costs approach replacement. For Seattle’s pre-WWII homes, we often find metal duct that can be patched and re-sealed for $180-$320 rather than $450-$680 for full replacement. We’ll show you the camera footage and give you both numbers so you can decide. Free estimates at (833) 700-5198.
Seattle’s historically heat-only systems never ran an annual cooling cycle to dehumidify duct interiors, so moisture, mold spores, and bio-debris accumulate in ways that don’t occur in markets where AC runs four months a year. This structural moisture trap means Seattle ductwork needs more frequent inspection and more aggressive sealing of crawl-space penetrations. The retrofit era also left more joints and splices to fail. If your Seattle home has never had central AC, your ducts have likely been wet inside for decades. Call (833) 700-5198 for a camera inspection and honest assessment.
Ready to stop losing heated air into your crawl space and start getting what you pay for from your furnace? Call Bellows Air Duct & Vent Co. of Seattle at (833) 700-5198. We’ll answer live, give you an upfront price, and stand behind our work with the 90-Day Done Right Promise. No bait coupons. No paperwork if something needs adjustment. Just a square deal, done right, backed in writing.
Written by Colin Merritt, Owner at Bellows Air Duct & Vent Co., serving Seattle since 2012.