Fast, Reliable Duct Repair & Sealing Across Los Altos
Duct repair and sealing in Los Altos typically runs $280-$650 for most residential jobs, with same-day service available throughout the 94022, 94023, and 94024 ZIP codes. We drive to Los Altos from our Bay Area dispatch points, and most appointments are booked within 24 hours. Call (844) 685-6342 for a free estimate with upfront pricing - the number we quote is the number on the invoice.
We’ve worked Los Altos ranch homes for over 42 years. We know the original trunk-and-branch sheet-metal systems in Old Los Altos, the flex-duct patches added during 1980s room expansions off Grant Road, and the detached workshops that need their own ventilation runs. Our technicians carry the equipment to complete most repairs in a single visit because we understand that Los Altos homeowners value their time and expect the job finished when we arrive.
Why Bellows Air Duct & Vent Co. Is Los Altos’s Preferred Duct Repair & Sealing Company
Our Duct Repair & Sealing team has built its Los Altos reputation on showing up when promised and leaving systems that stay sealed. We are not a coupon operation. Our 90-Day Done Right Promise means if a joint we sealed separates or a mastic application fails, we return at no charge - no paperwork, no arguing. That promise is stamped on every job.
Los Altos customers call us back because we camera-inspect before and after every repair. You see what we see: the cracked flex duct behind the wall, the smoke-blackened metal trunk line, the failed tape seal bleeding conditioned air into the crawl space. Visual proof beats verbal claims.
Calls are answered by a live person, 24 hours a day. Not voicemail. Not an app. A real person who can dispatch a background-checked, uniformed technician to your Los Altos home, usually same day or next.
We also offer $50 off any repair over $250, a free second opinion on any written estimate, and a permanent 5% senior and veteran discount. Our $89 seasonal tune-up catches small leaks before they become expensive problems.
Our Duct Repair & Sealing Services in Los Altos
Duct Sealing
Leaky ducts waste 20-30% of conditioned air in a typical Los Altos home. We seal joints, trunk connections, and register boots with professional-grade mastic sealant, not the hardware-store duct tape that fails within months. In neighborhoods around Foothill Expressway and throughout the 94024 ZIP, we’ve found that original 1960s metal systems have never been properly sealed - they were built for gravity furnaces and retrofitted for forced air without attention to pressure integrity. We fix that.
Flex Duct Repair
The ad-hoc flex-duct extensions common in Los Altos ranch additions are prone to insulation breakdown, kinking at bends, and joint separation where they connect to metal trunks. We replace damaged flex runs with properly sized, insulated duct and secure connections with mechanical fasteners and mastic. A patched system from a 1970s family-room expansion off Grant Road is not a design flaw - it’s a repairable condition we handle regularly.
Metal Duct Repair
Original sheet-metal ductwork in 1950s-1970s Los Altos homes rusts at seams, separates at joints, and accumulates decades of wildfire smoke residue that no filter change removes. We repair corroded sections, re-seal joints, and restore structural integrity. Our Rotobrush cleaning removes embedded debris before sealing, so the system operates as designed. Metal duct repair in Los Altos typically runs $340-$580 depending on linear footage and access.
Duct Insulation
Uninsulated or degraded duct insulation in crawl spaces and attics loses thermal energy and promotes condensation. We install new insulation on supply runs, paying special attention to garage and workshop feeds where Los Altos’s temperature swings are most extreme. Proper insulation maintains system pressure and protects against the moisture that corrodes metal over decades.
Mastic Sealant Application
Mastic is the only sealant we trust for permanent repair on Los Altos’s aging metal systems. Unlike tape, mastic remains flexible, penetrates seam irregularities, and lasts the life of the duct. We brush-apply it to every joint and connection after cleaning, then verify with camera inspection. Mastic sealing of a typical ranch-home system in Los Altos runs $280-$450.
Air Leak Repair
Pressure testing identifies leaks invisible to the eye. We pressurize the system, measure loss, and pinpoint exactly where conditioned air escapes. In Los Altos’s older homes with multiple renovation layers, this diagnostic prevents the guesswork that wastes money. Most air leak repairs are completed in one visit.
What happens when you call
- 1
A real person answersNo phone trees - you reach a local pro.
- 2
You get an upfront price rangeHonest numbers before anyone is dispatched.
- 3
A background-checked tech heads outLicensed & insured, dispatched right away.
- 4
You approve before work beginsNothing starts until you say go.
Trusted Brands We Service in Los Altos
We stock parts and service equipment from Honeywell, Aprilaire, and Nikro - the same brands specified by serious HVAC contractors. For Los Altos homeowners who’ve invested in whole-house air purification, this means we can integrate sealing and repair work with your existing Honeywell or Aprilaire system without compatibility issues. We carry common fittings and sealants on every truck, so we’re not driving to a supplier while your system sits open. Most Los Altos jobs are completed start to finish in a single visit.
Common Duct Repair & Sealing Problems We See in Los Altos Homes
- Smoke-embedded ductwork after wildfire seasons. Los Altos’s position at the base of the Santa Cruz Mountains funnels wildfire smoke directly onto older ranch homes, where decades of smoke residue and debris accumulate in original trunk-and-branch duct systems. Standard filter changes cannot address contamination baked into metal surfaces - cleaning and sealing are required.
- High-MERV filters and purifiers installed on uncleaned, leaky ducts. We regularly find that Los Altos homeowners have added whole-house air purifiers or upgraded filtration without addressing the underlying duct system. The new equipment simply recirculates decades of embedded particulates through gaps and separations. The purifier works; the distribution system defeats it.
- Failed handyman tape seals on flex-duct extensions. Ad-hoc flex-duct additions from past renovations develop insulation breakdown and joint separation. Tape applied as a quick fix dries and fails within months, creating hidden leaks that undermine system pressure and indoor air quality.
- Original metal ducts never sealed for forced-air retrofit. Many Los Altos ranch homes were built for gravity heat and later converted to forced air. The original metal trunk lines were never designed for the pressure of a blower motor, and joints that held by friction now leak continuously. Mastic sealing restores the pressure integrity the system was supposed to have.
Pricing for Duct Repair & Sealing in Los Altos, CA
| Service | Typical Range in Los Altos |
|---|---|
| Mastic sealing (whole system) | $280 - $450 |
| Flex duct repair/replacement (per run) | $180 - $340 |
| Metal duct repair (sectional) | $340 - $580 |
| Duct insulation (per linear foot) | $6 - $12 |
| Air leak diagnosis and repair | $220 - $420 |
| Full system inspection with camera | $89 - $150 |
These ranges reflect Los Altos’s market - labor costs, access conditions in older ranch homes with crawl spaces, and the prevalence of systems requiring cleaning before sealing. Every estimate is free and itemized before work begins. No bait pricing, no changes at the door. We also honor $50 off any repair over $250, and our $89 seasonal tune-up often catches issues before they reach these repair thresholds.
We Also Serve Cities Near Los Altos
Our service area extends throughout the Santa Clara Valley. We regularly dispatch to Los Altos from routes that also cover Mountain View, Sunnyvale, Cupertino, and Palo Alto. If you live near the Los Altos border in any of these cities, the same response times and pricing apply.
Serving Los Altos, CA - Our Local Coverage Area
We’re based in the Los Altos 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 Altos
Because the smoke particulates have embedded in your duct surfaces, not just the filter. Los Altos’s position at the base of the Santa Cruz Mountains funnels wildfire smoke directly into older homes, where residue bakes onto original metal ductwork over multiple fire seasons. A filter change only addresses airborne particles passing through - it cannot remove contamination adhered to duct walls. We clean with Rotobrush equipment and seal with mastic to restore the system. Call (844) 685-6342 for a free inspection.
Yes. We regularly service detached workshops and outbuildings in Los Altos’s acreage properties, including flex-duct and metal runs that feed these structures. The vibration from heavy-duty equipment and temperature swings in unconditioned spaces stress joints and insulation differently than main-house systems. We inspect, repair, and insulate these runs for proper pressure and thermal performance. Most workshop duct repairs are completed in one visit.
Professional-grade mastic sealant, brush-applied to clean metal, outlasts every tape product on the market. Mastic remains flexible, penetrates irregular seams, and does not dry and crack like duct tape or foil tape. On Los Altos’s original sheet-metal systems, mastic is the only sealant we guarantee. Application runs $280-$450 for a typical ranch-home system.
Yes. We install insulation on supply runs to garages, workshops, and outbuildings, using materials rated for the temperature extremes these unconditioned spaces experience. Proper insulation prevents condensation that corrodes metal ducts and maintains the system pressure your blower was designed to deliver. Insulation is typically added during repair or sealing work, not as a standalone service.
Every two to three years for homes with original systems, or annually if you’ve experienced wildfire smoke exposure or added high-MERV filtration. Los Altos’s smoke events, temperature inversions, and aging ranch-home infrastructure create conditions that accelerate joint degradation. Our $89 seasonal tune-up includes pressure testing and camera inspection. Call (844) 685-6342 to schedule - estimates are free.
We recently sealed a 1958 ranch home on Grant Road in Old Los Altos where the homeowner had installed an Aprilaire whole-house purifier without addressing the original metal ducts - after our Rotobrush cleaning and mastic sealing of joint separations, the new purifier actually started working as designed, dropping indoor particulate levels by 70%. That’s the difference between adding equipment and fixing the system it depends on.
Los Altos sits directly at the base of the Santa Cruz Mountains foothills, making it a first-capture zone for wildfire smoke that funnels down through the hills each fall - smoke particulates infiltrate HVAC systems and embed in ductwork in ways that standard filter changes cannot address. Compounding this, the city’s core housing stock of 1950s-1970s ranch homes still carries original sheet-metal or early flex-duct systems that have accumulated 50-plus years of allergens, debris, and smoke residue from multiple wildfire seasons, yet are routinely overlooked when affluent owners renovate kitchens and baths. The Santa Clara Valley’s persistent temperature inversions trap ground-level particulates - wildfire smoke, grass pollen from the surrounding hills, and orchard-era agricultural dust - keeping them cycling through residential HVAC systems far longer than in coastal cities with stronger onshore flow. Los Altos’s position at the valley’s western edge, immediately downslope from the fire-prone Santa Cruz Mountains, means duct contamination from smoke events is measurably heavier here than in flatland cities like Sunnyvale or Santa Clara a few miles east. Technicians working Old Los Altos neighborhoods regularly find that homeowners have added whole-house air purifiers or high-MERV filtration upgrades - common given the area’s tech-savvy, health-conscious clientele - without ever cleaning the underlying duct system first, meaning the new equipment is simply recirculating decades of embedded debris and smoke particulates already baked into aged sheet-metal runs.
Ready to fix the ductwork your filtration system depends on? Call Bellows Air Duct & Vent Co. at (844) 685-6342 for a free estimate. We’ll inspect with cameras, quote upfront, and complete most repairs in a single visit - backed by our 90-Day Done Right Promise in writing.
Written by Ray Castillo, Owner at Bellows Air Duct & Vent Co., serving Los Altos since 1984.