Fast, Reliable Duct Repair & Sealing Across Los Altos
Duct repair and sealing in Los Altos typically costs $280–$650 for most residential jobs, with same-week scheduling available throughout the 94022, 94023, and 94024 ZIP codes. If your ranch home’s original 1960s ductwork is leaking air into the crawlspace, blowing dust after a remodel, or struggling to keep rooms even, we’re the team that fixes it without cutting corners.
Richard Anderson, owner and lead technician at Landmark Air Duct Cleaning Service California, has spent 14 years working on the exact trunk-and-branch systems found in Los Altos’s 1950s–1970s housing stock. We’re familiar with the fiberglass-lined metal ducts in the Old Los Altos neighborhood, the uninsulated crawlspace runs near El Camino Real, and the post-remodel debris that contractors regularly leave behind in homes north of Foothill Expressway. When you call (833) 958-5022, Richard shows up — not a crew you’ve never met. Our Duct Repair & Sealing team handles everything from mastic resealing of deteriorating liner to full flex duct replacement after additions.
Why Landmark Air Duct Cleaning Service California Is Los Altos’s Preferred Duct Repair & Sealing Company
Los Altos homeowners aren’t looking for the cheapest bid — they’re looking for someone who won’t damage a $3 million property’s aging infrastructure or track construction dust through a finished interior. Richard Anderson personally leads every job, and that accountability shows in our numbers: 364+ verified customer reviews averaging 4.9 stars, built across 14 years of focused air-duct work.
Our response time to Los Altos is typically 24–48 hours for standard repairs, and we keep Nikro negative-air equipment and Rotobrush rotary systems on every truck — the same tools commercial restoration contractors use, not a shop vac and a sales pitch. We know the local permit landscape, the general contractors who pre-schedule post-remodel duct cleaning as standard close-out, and the specific failure modes that vintage Los Altos duct systems develop. That local fluency means faster diagnosis, cleaner repairs, and no surprises when we open a crawlspace and find 1962 sheet metal with crumbling fiberglass liner.
Our Duct Repair & Sealing Services in Los Altos
Mastic Sealant Application
Standard foil tape fails on the fiberglass-lined ductwork common in Los Altos ranches — it can’t bond to deteriorating liner, and the adhesive degrades in crawlspace temperature swings. We use professional-grade mastic sealant, brushed or sprayed onto joints and seams, to create a permanent flexible seal that won’t release glass fibers into your living space. On a recent job in the Old Los Altos neighborhood, we sealed a trunk-and-branch metal duct system in a 1965 ranch home that had been partially disconnected during a kitchen remodel. The homeowner reported uneven heating in the addition; we used mastic to reattach the flex duct runs and restored full airflow, matching the existing Honeywell zoning controls for seamless integration. Mastic sealing a typical Los Altos trunk system runs $320–$480.
Metal Duct Repair
Original sheet-metal trunk-and-branch systems in Los Altos homes weren’t designed for the static pressure loads of modern HVAC equipment. We see crushed sections from past renovations, rusted low-point drains, and separations at register boots where decades of thermal cycling have loosened the original fasteners. Richard Anderson repairs these with matching gauge galvanized steel, proper mechanical fastening, and mastic finish — never duct tape. A section replacement in a Los Altos crawlspace typically runs $180–$340 per linear foot of trunk, with most residential repairs falling in the $380–$620 range.
Flex Duct Repair & Replacement
Flex duct connectors added during 1980s–2000s HVAC upgrades often used incompatible fittings with the older 8-inch trunk takeoffs standard in Los Altos ranches. The result: air leaks, condensation in crawlspaces, and temperature imbalances between rooms. We replace deteriorated flex with properly sized, insulated flex duct and secure it with mechanical collars sealed in mastic — not zip ties and hope. Flex duct repair in Los Altos typically costs $220–$420 per run, depending on crawlspace access and length.
Duct Insulation for Uninsulated Crawlspace Runs
Many Los Altos ranch homes have bare metal trunk lines running through vented crawlspaces — code-legal when built, but now a major efficiency loss and condensation risk. We wrap existing ducts with formaldehyde-free fiberglass insulation jacket, sealed at all seams, or replace uninsulated sections with pre-insulated flex where appropriate. Full crawlspace trunk insulation in Los Altos runs $680–$1,200 for typical single-story homes.
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 Altos
We maintain stock of common repair components for the systems Los Altos homeowners actually have: Honeywell zoning controls and damper actuators, Aprilaire media filters and fresh-air intakes, and Guardsman sealants for fire-rated applications. Our trucks carry Rotobrush and Nikro equipment for pre- and post-repair cleaning, plus the specialized mastic and mechanical fasteners that vintage ductwork demands. When we encounter an unusual configuration — say, a custom Honeywell zone panel in a remodeled Loyola Corners home — we source compatible parts fast, because Richard Anderson has built relationships with regional HVAC distributors over 14 years. No waiting two weeks for a specialty fitting while your system runs half-open.
Common Duct Repair & Sealing Problems We See in Los Altos Homes
- Fiberglass liner deterioration releasing particles. The original fiberglass-lined metal ducts in Los Altos’s 1950s–1970s ranches have reached end of life. The liner crumbles, releases fibers into airflow, and standard tape repairs make it worse by trapping and shredding the material. We identify compromised liner and seal or replace sections with mastic and proper mechanical methods.
- Post-remodel debris and disconnected runs. Los Altos’s extraordinary property values drive constant permitted kitchen, bath, and addition work. Contractors routinely disconnect flex runs for access, then reconnect them poorly — or not at all. We find crushed flex, open boots, and drywall-compound-packed registers in newly finished spaces.
- Blown seals from static pressure mismatch. Original trunk-and-branch systems were designed for lower airflow volumes. Modern high-efficiency furnaces and added zoning create pressure that blows mastic joints and register boots. We calculate proper damper settings and reinforce connection points.
- Incompatible flex duct connectors causing condensation. The 8-inch trunk takeoffs common in Los Altos ranches don’t mate cleanly with modern 9-inch or 10-inch flex. Gaps pull crawlspace air, creating moisture and mold risk. We transition properly with reducing collars and sealed mechanical connections.
Pricing for Duct Repair & Sealing in Los Altos, CA
Most Los Altos duct repair and sealing jobs fall between $280 and $650, with larger crawlspace insulation projects or multi-zone resealing reaching $900–$1,400. Here’s how typical line items break down:
- Mastic sealant resealing (standard trunk-and-branch system): $320–$480
- Metal duct section repair/replacement: $180–$340 per linear foot; typical residential repair $380–$620
- Flex duct repair or replacement (per run): $220–$420
- Duct insulation (crawlspace trunk lines): $680–$1,200
- Post-remodel full system inspection and spot sealing: $280–$450
What moves the needle: crawlspace access difficulty, presence of asbestos-containing duct wrap (requires abatement referral), and whether we need to coordinate with an active general contractor’s schedule. We don’t upsell full replacement when targeted repair solves the problem. Every estimate is free, delivered in writing, and valid for 30 days. Call (833) 958-5022 to schedule — Richard Anderson will walk your system and give you the exact number.
We Also Serve Cities Near Los Altos
Our service radius covers the full Peninsula corridor, including Los Altos Hills for estate-scale duct systems, Mountain View and Sunnyvale for the tech-sector homeowners who track indoor air quality data, and Stanford for faculty housing and historic properties with similarly vintage infrastructure. Same equipment, same owner-led accountability, same 4.9-star standard.
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
Yes — we replace crushed sheet-metal sections with matching gauge galvanized steel, properly fastened and mastic-sealed, and we inspect adjacent fiberglass liner for damage that could release fibers. A typical 1962 ranch repair in Los Altos runs $380–$620 depending on crawlspace access and the length of damaged trunk. Call (833) 958-5022 for an exact quote — estimates are free.
Yes, and this requires specific technique: we never use standard tape on deteriorating fiberglass liner, which shreds the material and releases glass fibers into your living space. We apply professional mastic sealant that bonds to metal and encapsulates compromised liner without disturbance. Sealing a typical Los Altos fiberglass-lined trunk system costs $320–$480. Call (833) 958-5022 for an exact quote — estimates are free.
Sealing should follow cleaning in this situation — we first use Rotobrush and Nikro negative-air extraction to remove construction debris, then seal any joints that were disturbed during the remodel. Many Los Altos general contractors now pre-schedule this two-step process as standard project close-out. Post-remodel inspection, cleaning, and spot sealing typically runs $450–$680. Call (833) 958-5022 for an exact quote — estimates are free.
Leaking ducts are the most common cause of room-to-room temperature variation in Los Altos’s aging ranch systems, especially where flex connectors have separated or original mastic has failed. We pressure-test the system, identify leak points, and seal or repair as needed — often restoring balance without touching your Honeywell or other zoning controls. Diagnostic and repair typically runs $280–$550. Call (833) 958-5022 for an exact quote — estimates are free.
Yes — we insulate bare metal trunk lines with formaldehyde-free fiberglass jacket or replace sections with pre-insulated flex, depending on your system’s configuration and access. Uninsulated ducts in Los Altos’s vented crawlspaces lose significant efficiency and create condensation risk. Full crawlspace insulation for a typical single-story Los Altos home runs $680–$1,200. Call (833) 958-5022 for an exact quote — estimates are free.
Written by Richard Anderson, Owner at Landmark Air Duct Cleaning Service California, serving Los Altos and the greater Peninsula area since 2010.