Fast, Reliable Duct Repair & Sealing Across Boulder
Duct repair and sealing in Boulder typically runs $280-$850 depending on the scope, and most jobs are completed in a single visit. If your home is pulling in wildfire ash, losing heated air to the crawlspace, or struggling with uneven temperatures between rooms, sealed ductwork is the fix.
We’ve been driving up the Diagonal Highway to Boulder since 1984. Our technicians know the difference between a 1960s ranch off Table Mesa Drive and a converted rental on University Hill near CU Boulder, and we treat them accordingly. Calls to (844) 685-6342 are answered by a live person, 24 hours a day, and we schedule arrival windows we actually keep.
Why Bellows Air Duct & Vent Co. Is Boulder’s Preferred Duct Repair & Sealing Company
Forty-two years in this trade means we’ve seen what Boulder’s unique conditions do to ductwork. The 2021 Marshall Fire deposited smoke particulates into systems across the city, and the Chinook winds that tear through Boulder Canyon at 100-plus mph create pressure differentials that pull outdoor contaminants through every unsealed joint. Generic duct companies don’t account for this. We do.
Our Duct Repair & Sealing team carries mastic sealant, R-8 insulation wrap, and professional-grade equipment from Nikro and Honeywell on every truck. Every job starts and ends with a camera inspection, so you see the gaps before we seal them and the sealed result after. Our 90-Day Done Right Promise covers every Boulder home we touch: if it’s not right, we return at no charge, no paperwork, no arguing.
Background-checked, uniformed technicians. Upfront pricing disclosed before a single tool is lifted. The number on the phone is the number on the invoice.
Our Duct Repair & Sealing Services in Boulder
Mastic Sealant Application
Mastic is the only proper sealant for metal duct joints, and it’s what we apply to the unsealed sheet-metal connections common in 1950s-1970s Boulderranches. Paint-on sealants and tape fail within months in Boulder’s temperature swings; mastic remains flexible and airtight for years. We recently sealed a flex duct run in a 1950s ranch home on Table Mesa Drive in South Boulder (80305) where original sheet-metal ductwork had never been serviced. After the Marshall Fire, loose joints were sucking in wildfire ash from the crawlspace; we applied mastic sealant and re-insulated the ducts with R-8 wrap, stopping the infiltration. A typical mastic sealing job in Boulder runs $280-$520.
Duct Insulation Replacement
At 5,430 feet in Boulder’s semi-arid climate, uninsulated or degraded duct insulation wastes serious energy. Crawlspace ducts in older homes along Boulder Creek still carry moisture damage from the 2013 flood, and compromised insulation creates condensation points where mold takes hold. We strip damaged wrap, treat affected metal, and install fresh R-8 insulation rated for Colorado’s temperature extremes. Most insulation replacement jobs in Boulder fall between $340-$680.
Air Leak Repair
Disconnected flex duct, corroded metal seams, and poorly sealed return plenums leak conditioned air into attics and crawlspaces. In Boulder’s student rental market near CU Boulder, years of tenant turnover mean small leaks go unaddressed until airflow is cut in half. We pressure-test the system, identify every leak with camera verification, and repair with proper materials, not duct tape. Air leak repair in Boulder typically ranges $320-$620.
Metal Duct Repair
Original galvanized ductwork in South Boulder and Table Mesa homes corrodes at seams and hanger points after sixty-plus years. We patch, reinforce, or section-replace metal runs, always sealing with mastic, never tape alone. Where metal is too far gone, we transition to modern flex duct with proper support and sealing. Metal duct repair in Boulder generally runs $380-$850 depending on linear footage and access difficulty.
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.
Trusted Brands We Service in Boulder
We stock parts and specify equipment from Nikro, Honeywell, and Aprilaire, the same brands serious HVAC contractors in Boulder rely on for permanent repairs. This means no waiting on special orders for standard fittings, and no improvised solutions that fail the next Chinook season. Our trucks carry R-8 insulation wrap, professional-grade mastic, and replacement flex duct in common diameters so most Boulder jobs finish in one visit.
Common Duct Repair & Sealing Problems We See in Boulder Homes
- Wildfire ash infiltration through unsealed joints. The Marshall Fire pushed smoke into duct systems across Boulder, and loose metal joints in older homes continue pulling in particulates during high-wind events. Mastic sealing stops this migration at the source.
- Neglected flex ducts in student rentals near CU Boulder. Properties in 80302 and 80303 accumulate years of particulate buildup and rodent damage between tenants, but landlords rarely schedule sealing repairs until mold or severe airflow loss forces the issue.
- Post-flood moisture damage in crawlspace ductwork. The 2013 Boulder flood drove water into crawlspaces along Boulder Creek, and many homes still have compromised insulation and corroded metal that was never properly dried, sealed, or replaced.
- Negative pressure drawing in dust during Chinook wind events. Unsealed metal joints in South Boulder ranches create suction that pulls crawlspace dust, pollen from surrounding grasslands, and road grit directly into living spaces when canyon winds hit.
Pricing for Duct Repair & Sealing in Boulder, CO
Honest pricing means you know the range before we start. Here’s what duct repair and sealing costs in Boulder’s market:
- Mastic sealant application (standard residential system): $280-$520
- Duct insulation replacement (partial system): $340-$680
- Air leak repair (diagnosis + sealing): $320-$620
- Metal duct repair / section replacement: $380-$850
- Full system sealing + insulation upgrade: $720-$1,400
Factors that move the needle: accessibility (crawlspace vs. basement), linear footage of ductwork, extent of damage or corrosion, and whether we find additional leaks during camera inspection. We disclose the full price before work begins. No bait coupons, no changes at the door. Call (844) 685-6342 for a free estimate, exact to your Boulder home.
Standing offers: $50 off any repair over $250. Free second opinion on any written estimate. Permanent 5% senior and veteran discount.
We Also Serve Cities Near Boulder
Our technicians regularly cross into Louisville, Lafayette, Erie, and Broomfield for duct repair and sealing calls. The same Marshall Fire contamination and Chinook wind pressure issues affect homes throughout the region, and we bring the same camera-verified process and upfront pricing to every address. If you’re in a neighboring community and need Duct Repair & Sealing in Boulder or the surrounding area, we cover your ZIP code.
Serving Boulder, CO - Our Local Coverage Area
We’re based in the Boulder 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 Boulder
The Marshall Fire deposited smoke particulates and ash into duct systems across Boulder in December 2021, and unsealed joints continue allowing these contaminants to circulate during wind events. Homes that were not professionally cleaned and sealed after the fire still harbor residue in ductwork, particularly in older homes with original metal joints that were never properly mastic-sealed. If you smell smoke when your system runs or notice increased dust, your ducts likely need sealing. Call (844) 685-6342 for a free inspection and exact quote.
High tenant turnover in 80302 and 80303 means duct maintenance is deferred for years, allowing flex duct damage, rodent intrusion, and joint separation to worsen unchecked. Landlords typically only call when airflow fails entirely or mold appears, by which point sealing costs have doubled. Proactive sealing every five to seven years prevents this escalation. We offer upfront pricing for rental properties with no surprises for either owner or tenant. Call (844) 685-6342 to schedule.
Yes, proper mastic sealing of all duct joints eliminates the negative pressure that draws outdoor air, including dust, pollen, and wildfire particulates, into your system during high-wind events. Boulder’s Chinook winds create pressure differentials unique to this elevation and topography, and unsealed ducts act like straws sucking in whatever is outside. Sealed ducts maintain controlled, filtered airflow regardless of canyon wind speeds. Most sealing jobs are completed in one visit. Call (844) 685-6342 for a free estimate.
R-8 fiberglass duct wrap with a reinforced vapor barrier is the standard we install in Boulder’s crawlspaces, where temperature swings and residual moisture from the 2013 flood still challenge lesser materials. At 5,430 feet elevation, thinner insulation allows heat loss and condensation that leads to mold. We remove damaged old wrap, treat corroded metal, and install fresh R-8 with proper overlap and sealing. Typical crawlspace insulation replacement in Boulder runs $340-$680. Call (844) 685-6342 for exact pricing on your home.
Yes, especially in Boulder’s market where these homes represent a large share of available housing and replacement is often impractical. Original sheet-metal ductwork is structurally sound but was installed with unsealed joints that leak 20-30% of conditioned air; mastic sealing restores efficiency without the cost of full duct replacement. We camera-inspect first to assess metal condition, then seal and insulate to modern standards. Most 1950s ranch sealing jobs in Boulder fall between $280-$520. Call (844) 685-6342 for a free inspection and honest assessment.
Ready to stop losing heated air to your crawlspace and breathing whatever the Chinook winds drag in? Call (844) 685-6342 for a free estimate on duct repair and sealing in Boulder. We’ll show you the gaps on camera, quote one honest price before we start, and stand behind the work with our 90-Day Done Right Promise. Live person answering, 24 hours a day.
Written by Ray Castillo, Owner at Bellows Air Duct & Vent Co., serving Boulder since 1984.