Fast, Reliable Duct Repair & Sealing Across San Francisco
Most duct repair jobs in San Francisco run $280-$650 and our Duct Repair & Sealing crew can usually be there same day or next. We’re familiar with the parking constraints on Nob Hill, the tight alley access in the Mission, and the multi-unit coordination that Victorian flats always seem to require. Call (855) 401-6006 and you’ll reach a live person, 24 hours a day. We’ll give you an honest price before we lift a single tool, and we stand behind the work with our 90-Day Done Right Promise in writing.
Why Bellows Air Duct & Vent Co. of California Is San Francisco’s Preferred Duct Repair & Sealing Company
We’ve been serving California homeowners since 1984, and Roger Castañeda has built this company on the idea that a square deal shouldn’t be rare. In San Francisco, that means showing up when we say we will, working around your building’s access quirks, and never treating your Victorian flat like a suburban ranch house.
Our technicians are background-checked and uniformed, and they’ve worked in enough San Francisco buildings to know that a standard San Francisco HVAC Cleaning repair rarely exists here. The ductwork in a 1920s Edwardian on 94127’s Monterey Boulevard isn’t the same as what you’d find in a new build. We bring Rotobrush inspection cameras and the patience to work in cramped chases where other companies won’t bother.
Calls are answered by a live person, not an app or a voicemail tree. Most jobs finish in one visit. And our pricing is disclosed upfront, before work begins, consistent with the number you were quoted on the phone.
Our Duct Repair & Sealing Services in San Francisco
Duct Sealing
Leaky ducts waste 20-30% of heated and cooled air in most San Francisco homes, and in older buildings with retrofit ductwork that percentage climbs higher, which is why Air Duct Cleaning - San Francisco matters. We seal joints, seams, and connections using professional-grade mastic sealant and metal-backed tape rated for the humidity that San Francisco’s marine layer pushes through building envelopes year-round. Our camera inspection verifies the seal before we leave, so you see the difference, not just hear about it.
Flex Duct Repair
Flex duct gets crushed during retrofit installation in San Francisco’s tight floor cavities, or it degrades after years of flexing in spaces never designed for HVAC. We replace damaged runs with properly sized flex duct, support it to prevent sagging, and seal every connection. In Victorian flats where the original run snakes between tenant units, we often need custom lengths and careful routing, our Duct Repair & Sealing in San Francisco team has the experience to get it right without unnecessary demolition.
Metal Duct Repair
Rigid metal duct panels pop loose in narrow floor cavities as San Francisco’s old buildings settle, especially on hillsides in Noe Valley and Visitacion Valley. We reseat panels, reinforce seams, and apply mastic sealant to stop air from bypassing into dead spaces between walls. Where corrosion has eaten through galvanized steel from decades of condensation, we section in new metal or transition to flex duct where space demands it.
Duct Insulation & Mastic Sealant
San Francisco’s cool, moisture-laden marine layer raises indoor humidity even on sunny days. Uninsulated or poorly sealed ducts sweat, and that condensation breeds mold in ways dry-summer Central Valley cities never see. We wrap repaired runs with new duct insulation and seal every penetration with mastic sealant formulated to withstand persistent coastal moisture. In pre-1980 homes, we first identify any asbestos-wrapped insulation or original asbestos-backed duct tape that must be handled before repair work proceeds.
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 San Francisco
We stock parts and materials from Abatement Technologies, Nikro, and Rotobrush, the same brands serious HVAC contractors specify for commercial jobs, including Carrier repair in San Francisco work. For San Francisco homeowners, that means faster turnaround without waiting for special orders to clear the bridge. We also work with Honeywell and Aprilaire components when your system calls for them. Our trucks carry the mastic sealant, duct insulation, and flex duct sizes most common in San Francisco’s older housing stock, so we’re not making multiple trips while your system stays offline.
Common Duct Repair & Sealing Problems We See in San Francisco Homes
- Building settlement pops rigid duct seams in hillside neighborhoods. Noe Valley and Visitacion Valley homes on sloped lots see more than their share of separated metal duct panels as foundations shift over decades. The air escapes into wall cavities, and your furnace or heat pump works harder for no gain.
- Improper mastic application fails within months under coastal humidity. Discount repairs using consumer-grade tape or thin mastic don’t survive San Francisco’s persistent moisture. We see the failed jobs regularly, the sealant cracked, the tape peeling, the leak returned worse than before.
- Flex duct crushed in retrofit installations restricts airflow and traps moisture. Technicians working in chases never designed for HVAC sometimes force oversized flex duct through openings too small. The duct kinks, airflow drops, and the stagnant air becomes a breeding ground for mold.
- Multi-unit buildings hide co-mingled debris and cross-contamination. In the dense Victorian flats of the Mission District, a single duct system often crosses between separately-tenanted floor units with no clean-out access between levels. We regularly discover decades of accumulated debris from multiple households, and we coordinate building-wide access before work begins.
Pricing for Duct Repair & Sealing in San Francisco, CA
Here’s what honest pricing looks like for San Francisco’s market. A typical flex duct repair in a Victorian flat runs $280-$420. Metal duct panel reseating and reinforcement runs $320-$480. Full duct sealing for a small single-family home or flat unit runs $450-$650. Duct insulation replacement, where we strip old wrapping and install new, runs $380-$580 depending on linear footage. These ranges assume standard access; tight chases or multi-tenant coordination may add labor time, and we’ll tell you before we start.
Factors that affect your specific cost: accessibility of the duct run, whether asbestos-wrapped material requires safe handling, the extent of mold remediation needed before sealing, and whether we’re coordinating with multiple tenants in a multi-unit building. We disclose all of this upfront. No bait coupons, no price changes at the door. Estimates are free. Call (855) 401-6006.
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 San Francisco
Our technicians work throughout the city and in nearby neighborhoods including San Francisco‘s Mission District, Noe Valley, Chinatown, and Visitacion Valley. Same-day and next-day scheduling applies across our service area.
Serving San Francisco, CA - Our Local Coverage Area
We’re based in the San Francisco 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 San Francisco
San Francisco’s persistent marine layer pushes cool, moisture-laden air through building envelopes year-round, raising indoor humidity even on sunny days. This means duct systems sit in damp conditions for months, promoting mold colonization and degrading sealants that would hold fine in drier climates. We use marine-layer-proof mastic sealant and verify every seal with camera inspection to prevent moisture intrusion after repair. Call (855) 401-6006 for a free estimate.
Mastic sealant applied with a brush or caulking tool is the most reliable method for tight floor cavities where metal tape can’t be wrapped around joints. We recently repaired a leaking metal duct in a Nob Hill Victorian flat where the original run had been retrofitted through a floor void between two units. Access required cutting a 12-inch panel in a tenant’s closet, and we sealed the joint with mastic sealant and wrapped it with new duct insulation to prevent condensation mold. Call (855) 401-6006 to schedule.
Yes, frequently. In the dense Victorian flats of the Mission District, a single building’s duct system often crosses between two or three separately-tenanted floor units with no clean-out access between levels. We handle the coordination, explain the scope to each tenant, and schedule access that works for everyone. Estimates are free. Call (855) 401-6006 to get started.
Yes, but asbestos identification and safe handling must happen before any repair or sealing work proceeds. Pre-1980 buildings, a large majority of San Francisco’s housing stock, frequently have asbestos-wrapped duct insulation or original asbestos-backed duct tape. We’re trained to recognize these materials and work with certified abatement partners when removal is required. We never disturb asbestos-containing material without proper containment. Call (855) 401-6006 for an inspection.
During regional fall wildfire events, such as the 2018 Camp Fire that pushed AQI above 200 in San Francisco, residents seal windows and recycle air through duct systems, depositing fine particulate ash throughout the ductwork. This ash is abrasive and can degrade existing seals, and it creates demand for both San Francisco Dryer Vent Cleaning and resealing afterward. We inspect for seal degradation during post-wildfire cleanings and reseal any compromised joints. Call (855) 401-6006 to schedule an inspection after heavy smoke events.
Written by Roger Castañeda, Owner at Bellows Air Duct & Vent Co. of California, serving San Francisco since 1984.