Fast, Reliable Duct Repair & Sealing Across Los Angeles
Duct repair and sealing in Los Angeles typically costs $280-$650 for most residential jobs, with mastic sealant work on a standard Valley tract home running $320-$480 and flex duct repair in older retrofit systems ranging $180-$340 per section. Most of our Duct Repair & Sealing jobs in Los Angeles are completed in a single visit, and we answer calls with a live person 24 hours a day at (844) 685-6342.
We’ve been working in Los Angeles homes since 1984, and we know the difference between a house that was built with central air and one that had it shoehorned in later. The 1950s stucco ranches across the San Fernando Valley, the post-war bungalows in Highland Park, the hillside homes in Echo Park - each carries its own ductwork story, usually involving decades of dust, retrofit flex duct, and joints that were never properly sealed to begin with. Our technicians are background-checked, uniformed, and equipped to handle what they find, not to sell you what you don’t need.
Why Bellows Air Duct & Vent Co. Is Los Angeles’s Preferred Duct Repair & Sealing Company
Bellows has served Los Angeles homeowners for over 42 years. Ray Castillo leads our operation, and our reputation here is built on one thing: we return only when scheduled, never because the job failed. Our 90-Day Done Right Promise means if the seal doesn’t hold, we come back at no charge with no paperwork to file.
Los Angeles customers tell us they chose us after a discount coupon turned into a four-figure upsell. We don’t work that way. Our pricing is disclosed before we lift a single tool, and the number we give on the phone is the number on the invoice. Camera inspection before and after every job gives you a visual record, not a verbal claim.
We answer calls live, 24/7. Not an app. Not a callback queue. A real person who can dispatch a technician to Koreatown, Silver Lake, or the Valley today. Most repairs are completed in one visit because our trucks carry the parts and equipment - Rotobrush agitation systems, professional-grade mastic, and flex duct inventory sized for the retrofitted systems common in Los Angeles.
Our Duct Repair & Sealing Services in Los Angeles
Duct Sealing & Air Leak Repair
Los Angeles homes lose 20-30% of conditioned air through leaks on average, and in the Valley’s 1960s tract houses with retrofit flex duct, we’ve measured losses above 40%. The LA Basin’s thermal inversion traps exhaust and industrial particulate at breathing level year-round, so every leak pulls that dirty air into your living space while your system works harder to compensate. We seal with mastic compound and metal-backed tape rated for California Title 24 energy standards, then verify with pressure testing. A typical duct sealing job in Los Angeles runs $320-$550 for a single-zone system.
Flex Duct Repair
Flex duct in older Los Angeles homes - the ribbed plastic stuff snaked through attics in the 1970s and 1980s - collapses, tears, and separates at joints. We’ve replaced crushed flex runs in Woodland Hills where a contractor walked through the attic twenty years ago and never told the homeowner. Our crew sizes replacement flex for the static pressure demands of your system, supports it with proper strapping, and seals every connection with mastic. Flex duct repair in Los Angeles typically costs $180-$340 per section, with full attic replacement on a Valley ranch running $1,200-$2,100.
Metal Duct Repair
Galvanized metal duct in pre-war homes and some commercial conversions around Downtown Los Angeles corrodes at seams and collects debris in low spots. We patch with matching gauge metal, seal with high-temperature mastic, and reinsulate where the original wrap has degraded. Metal repair is slower work, often in tight crawl spaces or behind walls, but it’s permanent when done right. Most metal duct repairs in Los Angeles fall between $260-$580.
Duct Insulation & Mastic Sealant
Uninsulated or poorly insulated duct in Los Angeles attics bleeds cooling into 140-degree summer air. We apply closed-cell insulation and vapor barrier where code requires it, with particular attention to the Santa Ana wind paths that blast through attic vents and strip away loose wrap. Mastic sealant application - brushed onto every joint and seam - is the backbone of our sealing work. It takes longer than tape alone, but it outlasts the tape by decades. A full mastic sealant job on a typical Woodland Hills ranch house takes 4-6 hours and runs $380-$620.
We sealed a 1960s stucco tract home in Woodland Hills where Santa Ana winds had blown desert grit through unsealed attic duct joints for decades. Our crew used Mastic Sealant and Rotobrush agitation to lock down every leak in the flex duct, restoring static pressure and stopping the fine dust that had been coating every room.
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 Los Angeles
We stock parts from Rotobrush, Abatement Technologies, and Aprilaire - the same brands serious HVAC contractors specify for Los Angeles’s demanding climate. Our trucks carry mastic sealant rated for the temperature swings of Valley attics, flex duct sized for the negative-pressure systems common in retrofit installations, and HEPA-filtered equipment for post-wildfire contamination jobs. That inventory means we don’t order parts and return next week. We finish today.
Common Duct Repair & Sealing Problems We See in Los Angeles Homes
- Santa Ana wind infiltration through attic penetrations. Every fall, desert winds blast through unsealed duct joints in Valley and foothill attics, recontaminating systems within weeks of a standard cleaning. We see this in Woodland Hills, Granada Hills, and across the north Valley - dust coating registers that were spotless in September.
- Wildfire ash degrading mastic adhesion. After the 2025 Palisades and Eaton fires, we found ash residue on ductboard surfaces that prevented proper sealant bonding. Pre-cleaning with Rotobrush agitation is now standard for any sealing job in fire-affected zones.
- Retrofit flex duct collapsing under seal pressure. The 1950s-1970s Valley tract homes we work in were never designed for forced air. Flex duct was added later, often undersized, and improper sealing can choke airflow to a whisper. We test static pressure before and after to prevent this.
- Heavy-metal particulate from structure fires requiring special disposal. After the 2025 Palisades and Eaton fires, duct samples from foothill homes in Altadena showed barium and lead particulates from burned electronics and construction materials, requiring hazmat-level disposal not needed in less fire-prone suburbs like Irvine. This is Los Angeles’s reality now, and our protocols reflect it.
Pricing for Duct Repair & Sealing in Los Angeles, CA
Here’s what duct repair and sealing costs in the Los Angeles market:
| Service | Typical Range |
|---|---|
| Mastic sealant, single-zone system | $320-$550 |
| Flex duct repair (per section) | $180-$340 |
| Full flex duct replacement, attic | $1,200-$2,100 |
| Metal duct repair (seam/patch) | $260-$580 |
| Air leak detection & sealing | $280-$480 |
| Duct insulation (per linear foot) | $8-$14 |
What moves the price: accessibility (crawl space vs. walk-in attic), contamination level (standard dust vs. post-wildfire ash requiring HEPA pre-cleaning), and system size. We disclose the full price before starting, and our $50 Off Any Repair Over $250 applies to qualifying jobs. Seniors and veterans receive a permanent 5% discount. Call (844) 685-6342 for a free estimate - we’ll give you a firm number, not a range that doubles at the door.
We Also Serve Cities Near Los Angeles
Our Duct Repair & Sealing in Los Angeles crews work daily in Koreatown, Echo Park, Silver Lake, and Florence-Graham - the same technicians, the same trucks, the same upfront pricing. If you’re in these neighborhoods or anywhere in the LA Basin, we can usually schedule within 24 hours.
Serving Los Angeles, CA - Our Local Coverage Area
We’re based in the Los Angeles 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 Los Angeles
Yes. Santa Ana winds blast desert particulate through attic vents and any unsealed duct penetration at 40-60 mph, and we’ve documented fresh dust layers in Valley homes within 72 hours of a wind event. The only reliable prevention is thorough mastic sealing of all joints and registers, plus pressure-tested closure of attic bypass paths. Call (844) 685-6342 if you’ve noticed dust returning quickly after cleaning - we’ll inspect for leaks at no charge.
Yes, and in Los Angeles it’s often essential. Smoke from the 2025 Palisades and Eaton fires traveled miles downwind, infiltrating ducts through leaks and open returns in homes that were never near flames. Sealing prevents recontamination and protects your system during future events, which in LA means virtually every autumn. We recommend sealing combined with HEPA-filtered cleaning for any home within 10 miles of a major structure fire. Estimates are free - call (844) 685-6342.
Yes, substantially. Older Los Angeles homes - the 1950s-1970s Valley ranches especially - have flex duct that was retrofit through attics never designed for it, often with sharp bends, inadequate support, and negative pressure that collapses cheap replacement material. New construction uses properly sized, properly supported flex with adequate return air. We specify heavier-gauge flex and additional support straps for retrofits, and we test static pressure to confirm airflow. A typical older-home flex repair in Los Angeles runs $220-$380 per section versus $180-$280 in newer builds.
Structure fires release barium, lead, and other heavy metals from electronics, batteries, and treated building materials. After the 2025 Palisades and Eaton fires, duct samples from Altadena foothill homes showed levels requiring hazmat-level disposal, not standard residential waste. The metals adhere to duct surfaces and recirculate until professionally removed. This is specific to Los Angeles’s wildland-urban interface fires and largely absent in less fire-prone suburbs. If you live near a recent burn zone, we recommend testing before standard cleaning - call (844) 685-6342.
4-6 hours for a single-zone system with attic access. Woodland Hills ranches typically have 1,200-1,800 square feet of conditioned space with flex duct routed through a walk-in attic, which our crews can access and seal methodically. Post-wildfire jobs add 1-2 hours for HEPA pre-cleaning. We complete most jobs in one visit, and you’ll receive before-and-after camera footage. Schedule at (844) 685-6342 - we answer live 24/7.
We’re Bellows Air Duct & Vent Co., and we’ve served Los Angeles since 1984. Ray Castillo and our team stand behind every job with the 90-Day Done Right Promise - in writing, no arguing, no paperwork if something needs attention. If your ducts are leaking, contaminated, or haven’t been inspected in years, call (844) 685-6342 for a free estimate. We’ll give you one honest price before we start, and we’ll be there when we say.
Written by Ray Castillo, Owner at Bellows Air Duct & Vent Co., serving Los Angeles since 1984.