Fast, Reliable Duct Repair & Sealing Across San Antonio
Duct repair and sealing in San Antonio typically costs $280–$680 for most residential jobs, with flex duct replacement running $180–$340 per section and full mastic sealing of an attic trunk line ranging $450–$920. We’re usually on-site within 24–48 hours across the San Antonio metro, including Alamo Heights, Terrell Hills, Leon Valley, and Windcrest. Call (844) 886-2161 for a free estimate.
San Antonio’s older neighborhoods tell a story you won’t find in newer Texas suburbs. In King William, Dignowity Hill, and the historic Westside, homes built before WWII got central air decades later — often through hasty 1950s–1970s retrofits that are now failing in predictable ways. Our Duct Repair & Sealing team works exclusively on air pathways: we don’t install new HVAC systems, and we don’t send sales crews. Michael Brown, our owner, arrives as the lead technician with Rotobrush and Nikro equipment built for accessing and repairing the tight, cluttered attics these historic homes present.
The 78201–78210 ZIP codes are our regular territory. We know the alley-load access points, the low-pitch roofs, and the blown-in insulation depths that make ductwork in these homes a different job than tract housing in Helotes or Stone Oak.
Why Summit Air Duct Cleaning Service Texas Is San Antonio’s Preferred Duct Repair & Sealing Company
Eight years focused on one trade means we’ve seen the specific failure patterns that repeat across San Antonio’s housing stock. We’re not a general HVAC company that cleans ducts between installation jobs — this is what we do, and San Antonio’s older homes are where our expertise shows.
Our reputation here is built on 775 verified customer reviews averaging 4.9 stars. That’s a volume that rules out cherry-picking; it reflects consistent results across repeat service calls and referrals. San Antonio property managers in the urban core specifically request us for pre-sale inspections and tenant turnover work because we document what we find with photos and explain whether repair, sealing, or replacement is the right path.
Response time matters in a city where AC season stretches from April through October with barely a break. We schedule San Antonio calls within 24–48 hours, and we carry mastic sealant, insulated flex duct, and access port hardware on every truck — no waiting for parts while your system runs inefficiently.
Michael Brown works every job personally. Customers in San Antonio get the decision-maker doing the actual sealing and repair, not a subcontracted crew learning the house on your dime.
Our Duct Repair & Sealing Services in San Antonio
Mastic Sealant Application
Foil tape fails. In San Antonio attics, it fails faster. The temperature swings between our mild winters and brutal summers — plus the physical pressure of blown-in insulation added during energy retrofits — cause tape adhesive to degrade and joints to separate. We seal metal trunk lines and connections with mastic, a fiber-reinforced compound that remains flexible and airtight for decades. In homes near 78204 and 78203, we regularly apply mastic to original 1960s galvanized trunks that have never been properly sealed since installation.
Flex Duct Repair & Replacement
Flex duct crushed by insulation weight is one of the most common calls we get from San Antonio’s pre-WWII neighborhoods. The lightweight flex installed during mid-century retrofits wasn’t designed to support decades of compressed fiberglass or cellulose overhead. We remove damaged sections, install new R-6 or R-8 insulated flex with proper support straps, and ensure turns maintain a gentle radius rather than the kinked 90-degree angles that choke airflow to back bedrooms. In a King William craftsman bungalow, we found a 1960s galvanized trunk line sagging under attic insulation, with foil tape joints failing and flex duct kinked at a 90-degree turn. We replaced the damaged flex section with new insulated duct, sealed the trunk with mastic, and installed a Rotobrush access port for future maintenance — restoring airflow to two choked-off bedrooms.
Metal Duct Repair
Galvanized sheet-metal trunk lines in San Antonio’s historic homes corrode at seams, separate at joints, and occasionally get punctured during roofing or insulation work. We repair metal ducts with patch kits, custom-cut replacement sections, and proper mechanical fastening before sealing. These trunks often run through structural spaces that can’t be easily rerouted, so preserving and repairing the original metalwork is usually more practical than full replacement.
Duct Insulation & Condensation Control
San Antonio’s spring humidity spikes — May and June especially — create condensation on under-insulated attic duct runs. That moisture feeds mold growth inside ducts and degrades surrounding insulation. We install or replace exterior duct insulation with proper vapor barriers, focusing on the supply lines that carry 55-degree air through 130-degree attics. For homes in 78207 and surrounding historic Westside areas, this is often the critical repair that stops recurring mold calls.
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 Honeywell and Aprilaire air quality components for San Antonio customers who want integrated solutions — humidity controls, media filters, and UV sanitizing units that work with repaired duct systems. Our Rotobrush and Nikro equipment is the same professional-grade systems used by commercial restoration contractors, not the consumer-grade shop vacs some competitors bring to residential jobs. When we repair ducts in Terrell Hills or Alamo Heights homes with existing Aprilaire media cleaners, we ensure the sealed ductwork is sized and sealed to maintain the manufacturer’s rated static pressure. Parts availability means we don’t leave San Antonio attics half-finished waiting on orders.
Common Duct Repair & Sealing Problems We See in San Antonio Homes
- Foil tape joints failing after insulation retrofits. The energy-efficiency push of the 2000s–2010s added blown-in insulation across San Antonio’s older neighborhoods, but contractors rarely re-secured duct joints first. The weight pulls tape loose; the leaks pull attic air into your living space. Mastic sealing is the permanent fix.
- Flex duct kinked and partially collapsed by insulation weight. Standard cleaning brushes can’t restore airflow through a duct that’s physically pinched shut. We replace the damaged section and install proper support to prevent recurrence.
- Condensation and mold in under-insulated attic runs. San Antonio’s near-continuous AC season keeps ducts cold; our spring humidity spikes provide the moisture. The combination accelerates biological growth faster than in drier Texas metros like El Paso. Insulation repair and vapor-barrier sealing stop the cycle.
- Original galvanized trunks never cleaned since 1960s installation. In Dignowity Hill and King William, we regularly open systems that have accumulated six decades of construction debris, rodent activity, and deteriorated filter media — all sealed behind failing tape that was never meant to last.
Pricing for Duct Repair & Sealing in San Antonio, TX
Here’s what duct repair and sealing costs in the San Antonio market:
| Service | Typical Range |
|---|---|
| Mastic sealing of attic trunk line (up to 40 ft) | $450–$920 |
| Flex duct section replacement (per 25 ft run) | $180–$340 |
| Metal duct patch or seam repair | $220–$480 |
| Duct insulation replacement (per run) | $160–$310 |
| Access port installation for future maintenance | $85–$150 each |
| Full system assessment with photo documentation | Free estimate |
Factors that move San Antonio jobs toward the higher end: multiple attic access points needed, extensive blown-in insulation removal to reach ducts, active mold requiring sanitizing before sealing, and homes with no existing access ports requiring new cuts. Historic homes in 78204 and 78203 often require more labor due to tight clearances and original construction that never anticipated modern ductwork. We quote upfront after inspection — no open-ended hourly billing. Call (844) 886-2161 to schedule your free estimate.
We Also Serve Cities Near San Antonio
Our service radius includes Alamo Heights, Terrell Hills, Leon Valley, and Windcrest — communities with their own housing stock challenges, from Alamo Heights’ mid-century ranch homes to Windcrest’s established subdivisions with aging flex duct. Response times to these areas typically match our San Antonio core schedule. If you’re unsure whether your address falls within our coverage, call (844) 886-2161 and we’ll confirm.
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
The ductwork in these homes was installed as a retrofit decades after construction, often with mismatched materials and minimal support. Original galvanized trunks joined to flex duct with foil tape weren’t designed to handle blown-in insulation loads or sixty years of thermal cycling. Cleaning helps, but it can’t fix physically collapsed flex, separated joints, or insulation that’s fallen away. We assess whether repair and sealing will restore performance or if section replacement is the more durable path. Call (844) 886-2161 for a free inspection — we’ll show you exactly what your system needs.
Condensation on cold supply ducts during San Antonio’s May–June humidity spikes is the primary trigger. When attic duct insulation is compressed, missing, or improperly sealed at joints, the temperature differential between 55-degree conditioned air and 90-degree humid attic air produces moisture that feeds mold growth. This pattern repeats annually because the root cause — inadequate insulation and air leaks — isn’t addressed by cleaning alone. We repair insulation, seal joints with mastic, and can install UV sanitizing where biological growth has been persistent. Call (844) 886-2161 to stop the cycle before next spring.
No. Foil tape adhesive degrades within 5–10 years in attic conditions, and San Antonio’s temperature extremes accelerate that timeline. The tape also fails mechanically when insulation weight pulls at joints or when vibration from air handlers works edges loose. Mastic sealant is the correct material for permanent duct sealing — it remains flexible, fills irregular gaps, and isn’t compromised by the thermal and physical stress that ruins tape. We remove old tape residue and apply mastic to every joint we seal. Call (844) 886-2161 for an estimate on upgrading your duct seals.
We cut new access ports in strategic locations — typically at trunk line junctions or where flex duct transitions occur — then install permanent, gasketed panels for future service. In King William’s low-pitch roofs and compact attic spaces, we use our Nikro compact inspection systems to map duct layout before cutting, minimizing disruption. Michael Brown evaluates each home’s structure to find the access path that preserves your ceiling integrity while allowing complete duct service. Call (844) 886-2161 to discuss access options for your specific home.
Crushed flex duct requires section replacement — the wire helix and insulation are permanently deformed, and no cleaning or sealing process restores original airflow capacity. We remove the damaged section, install new insulated flex with proper support straps that prevent future compression, and seal connections with mastic. For San Antonio homes with extensive blown-in insulation, we also evaluate whether additional support brackets or insulation redistribution is needed to protect the repair long-term. Call (844) 886-2161 for a free assessment and exact quote.
Ready to fix the ductwork San Antonio’s climate and housing stock have been wearing down for decades? Michael Brown will arrive as your lead technician, assess your system with professional-grade equipment, and quote upfront — no pushy sales tactics, no subcontracted crews. Whether you’re in King William dealing with 1960s galvanized trunks or in Leon Valley with spring mold issues, we’ve handled it. Call (844) 886-2161 today for your free estimate.
Written by Michael Brown, Owner at Summit Air Duct Cleaning Service Texas, serving San Antonio since 2017.