Fast, Reliable Duct Repair & Sealing Across San Antonio
Duct repair and sealing in San Antonio typically runs $180-$650 depending on whether you need spot sealing, flex duct replacement, or full system remediation, and most jobs are completed in a single visit. If your utility bills are climbing, rooms won’t cool evenly, or you’re noticing dust pouring from vents after every construction season, your ductwork is likely leaking conditioned air into the attic or drawing contaminants back into your living space. Call (866) 347-2063 - we answer live, 24 hours a day, and we’ll give you an honest price before a single tool is lifted.
We’ve been serving Texas homeowners since 1984, and our San Antonio customers know the difference between a quick patch and a repair that holds. The Hill Country’s brutal attic heat, Gulf moisture surges, and that fine caliche dust that never quite settles - these aren’t abstract climate facts to us. They’re the conditions we plan for when we spec mastic sealant, choose duct insulation ratings, and route replacement flex duct through your 1960s bungalow near McCreless Market or your retrofit system off Fredericksburg Road.
Our background-checked, uniformed technicians carry R-8 insulated flex duct, professional-grade mastic from Abatement Technologies, and the camera equipment to show you exactly what’s failing before we start. Most San Antonio repairs are done same-day. We stand behind it with our 90-Day Done Right Promise - in writing, no arguing, no paperwork if something needs attention.
Why Bellows Air Duct & Vent Co. of Texas Is San Antonio’s Preferred Duct Repair & Sealing Company
San Antonio homeowners have kept us busy for over four decades because we treat retrofitted systems with the respect they deserve. A 1950s West Side bungalow with central AC shoehorned into a window-unit frame wasn’t built for modern airflow demands. We know where the original plaster meets the retrofit flex, where the caliche dust cakes thickest, and where Gulf moisture turns that dust into the sludge that corrodes metal fasteners.
Our reputation here is built on showing up when we say and leaving camera-verified results. Every job gets inspected before and after - a visual record, not just a claim. Customers in Alamo Heights and Terrell Hills call us back because the number on the phone matches the number on the invoice. No bait coupons, no price changes at the door.
Calls are answered by a live person, 24/7. Not a voicemail tree. Not an app. A real person who can dispatch a technician to King William, Dignowity Hill, or Windcrest with the right materials already on the truck. That’s how most San Antonio jobs finish in one visit.
We also honor a permanent 5% Senior and Veteran discount, and we never inflate prices to absorb it. A square deal means one honest price, shown before we start.
Our Duct Repair & Sealing Services in San Antonio
Duct Sealing
Leaky ducts waste 20-30% of conditioned air in a typical San Antonio home, and in our 8-9 month cooling season, that waste adds up fast. We seal supply and return plenums, trunk lines, and branch connections with Abatement Technologies mastic sealant - not tape that dries and curls in 150°F attic heat. For homes in 78211 and 78212, where 1940s masonry construction meets 1980s retrofit ductwork, we often find original mastic joints that failed decades ago, bleeding cooled air into unconditioned spaces.
A typical duct sealing job in San Antonio runs $180-$340 for partial system sealing, or $450-$650 for full trunk-and-branch remediation. We show you the camera footage so you see exactly where the leaks are.
Flex Duct Repair
Flex duct in San Antonio attics lives a hard life. That orange-tinge R-4 or R-6 insulation from the 1980s retrofit era has turned brittle after years of 150°F peak temperatures. We replace compromised sections with R-8 insulated flex duct rated for extreme thermal cycling, properly supported to prevent sagging that traps condensation.
In the 78201-78210 ZIP codes covering King William and the West Side, we regularly find flex duct that was undersized from the start - 6-inch runs trying to serve rooms that need 8-inch, strangling airflow and forcing your compressor to run longer. We size replacements correctly and seal every connection with mastic, not zip ties and hope. Typical flex duct repair in San Antonio: $220-$480 per run, depending on attic access and length.
Metal Duct Repair
Older San Antonio homes with galvanized steel trunk lines suffer a specific local failure pattern. Caliche limestone dust - that chalky white particulate from Edwards Plateau construction - combines with summer Gulf moisture to form an abrasive sludge that corrodes seams and fasteners from the inside. We’ve opened metal ducts in Government Hill homes where the bottom seam has rusted through completely, dumping conditioned air into the crawl space.
We repair or replace damaged sections, re-seal with mastic, and apply corrosion-resistant coatings where metal meets masonry. Metal duct repair in San Antonio typically ranges $280-$550.
Duct Insulation
Uninsulated or poorly insulated ductwork in a San Antonio attic is like running cold water through a hot pipe - condensation forms, insulation degrades, and your system works harder for less comfort. We install R-8 insulation on replacement flex duct and wrap exposed metal trunks with fiberglass insulation and vapor barrier, sealed at every seam. For homes near the 78213 ZIP code corridor, where 1960s ranch-style construction dominates, this upgrade often pays for itself in a single summer of reduced compressor runtime.
Duct insulation work in San Antonio runs $320-$580 depending on linear footage and attic accessibility.
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 Antonio
We stock parts and materials from Rotobrush, Honeywell, and Aprilaire - the same brands serious HVAC contractors specify for Texas installations. Our San Antonio trucks carry R-8 flex duct, Abatement Technologies mastic sealant, and insulated connectors so we’re not making supply runs while your attic heat soars. When a Kirby homeowner calls with a failed flex duct run on a Saturday, we don’t need to order parts. We need to drive.
This matters more in San Antonio than in milder climates. Every hour of delay means more conditioned air wasted, more caliche dust drawn through gaps, more strain on a compressor that’s already running nine months a year.
Common Duct Repair & Sealing Problems We See in San Antonio Homes
- Brittle flex duct liner from extreme attic heat. In San Antonio’s unconditioned attics, summer temperatures regularly exceed 150°F. Flex duct installed during the 1980s retrofit boom has exceeded its thermal lifespan. The liner cracks, the insulation compresses, and airflow drops by half before most homeowners notice anything wrong.
- Caliche-moisture sludge in metal ductwork. That fine white limestone dust from Edwards Plateau construction sites doesn’t stay outside. It penetrates poorly sealed return plenums, absorbs Gulf moisture during summer humidity surges, and forms a mold-prone paste that corrodes metal seams and contaminates indoor air.
- Failed mastic joints from thermal cycling. San Antonio’s daily temperature swings - 100°F afternoons, 75°F evenings, month after month - expand and contract duct materials constantly. Original mastic from 1980s retrofits cracks and separates, creating leaks that bypass conditioned air into attics and wall cavities.
- Undersized duct routes from window-unit conversions. Homes in 78207 and 78203 that swapped window units for central AC in the 1980s often have 6-inch flex duct serving rooms that need 8-inch or 10-inch. The system runs longer, wears faster, and never achieves the comfort the compressor is working for.
Pricing for Duct Repair & Sealing in San Antonio, TX
| Service | Typical Range in San Antonio | Most Common Price Point |
|---|---|---|
| Spot duct sealing (mastic, 1-3 joints) | $180-$260 | $220 |
| Partial system sealing (supply or return) | $280-$340 | $310 |
| Full trunk-and-branch sealing | $450-$650 | $520 |
| Flex duct repair/replacement (per run) | $220-$480 | $340 |
| Metal duct repair (sectional) | $280-$550 | $390 |
| Duct insulation upgrade | $320-$580 | $420 |
What moves you within these ranges? Attic accessibility matters - a tight 1940s bungalow crawl with original plaster lath takes longer than a modern ranch with a walk-up attic. The extent of caliche contamination affects prep time. And whether we’re sealing accessible trunk lines or chasing leaks through finished walls changes the scope significantly.
We don’t guess and we don’t bait. Our technician shows you the camera inspection, explains what needs doing, and gives you the exact price before work starts. Estimates are free. Call (866) 347-2063 to schedule.
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 Antonio
Our Duct Repair & Sealing team works throughout Bexar County and into the near suburbs. We regularly repair ductwork in Alamo Heights, where 1930s-1950s homes present similar retrofit challenges to San Antonio’s inner core. Terrell Hills and Kirby homeowners call us for attic insulation upgrades on ranch-style construction. In Windcrest, we address the same caliche and moisture patterns that affect San Antonio proper. Same live-answer dispatch, same camera verification, same 90-Day Done Right Promise.
Serving San Antonio, TX - Our Local Coverage Area
We’re based in the San Antonio 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 Antonio
Caliche limestone dust is finer, more abrasive, and more persistent than typical construction dust, and when it combines with Gulf moisture inside ductwork, it creates a sludge that corrodes metal fasteners and clogs airflow paths in ways standard national cleaning protocols don’t address. Our technicians recognize this chalky white buildup immediately - it’s unique to the Edwards Plateau karst substrate - and we modify our sealing and repair approach to remove it thoroughly and prevent re-accumulation. Call (866) 347-2063 for an inspection if you’re seeing white dust around your vents.
Yes, retrofitted systems from the 1980s almost always have higher sealing demands than original central AC installations. The duct routes were improvised through unconditioned attics, the flex duct is often undersized for the load, and the original mastic joints have failed under decades of San Antonio thermal cycling. We recently sealed a 1940s masonry bungalow on North Zarzamora Street in the West Side, where decades of uninsulated flex duct in a 150°F attic had turned the 30-year-old duct liner brittle and dust-laden with caliche. We replaced the compromised sections with R-8 insulated flex duct, applied Abatement Technologies mastic sealant at every joint, and restored sealed airflow to the retrofitted central system. If your home fits this profile, the repair need is real and typically urgent.
Attic temperatures in San Antonio regularly exceed 150°F from June through September, which accelerates the thermal degradation of flex duct liner, causes mastic sealant to crack and separate, and expands metal duct seams beyond their design tolerance. A repair that might last 15 years in a milder climate can fail in 8-10 years here. We spec materials rated for extreme thermal cycling - R-8 insulation minimum, high-temperature mastic, corrosion-resistant fasteners - and we verify with camera inspection that seals hold under operating pressure. For a free assessment of your attic ductwork’s condition, call (866) 347-2063.
Yes, we address moisture-driven mildew by sealing the leaks that draw humid attic air into the system, replacing degraded insulation that traps condensation, and applying antimicrobial treatments where biological growth is present. Gulf moisture surges push 70%+ relative humidity into poorly sealed return plenums and duct seams, creating the damp, dark conditions where mildew colonizes. Sealing alone often eliminates the moisture source; in cases of significant contamination, we recommend full duct cleaning before sealing to prevent spore redistribution. Every repair includes camera verification so you see the moisture pathways we’ve closed.
We recommend inspection every 3-5 years for masonry homes with 1980s retrofit ductwork, and every 5-7 years for newer systems with original central AC design. The combination of extreme attic heat, caliche dust, and thermal cycling in San Antonio wears seals and liners faster than national averages suggest. Our $89 Seasonal Tune-Up includes a camera inspection of accessible ductwork - a small investment against the 20-30% efficiency loss that leaking ducts typically cause. Call (866) 347-2063 to schedule, or ask about our Free Second Opinion if another company has recommended work you’re unsure about.
Written by Wade Kellerman, Owner at Bellows Air Duct & Vent Co. of Texas, serving San Antonio since 1984.