Duct Repair & Sealing in San Bruno - Leakage Measured, Then Priced in Writing

Fast, Reliable Duct Repair & Sealing Across San Bruno

Duct repair and sealing in San Bruno typically runs $180-$650 depending on whether you’re patching a flex-duct leak or replacing a degraded metal trunk line, and most of our San Bruno calls are completed same-day. We’re familiar with the post-WWII tract homes that dominate this city, the persistent marine fog that rolls through the San Bruno Gap, and the particular contamination that comes from living under active SFO flight paths. If your ducts are leaking heated air into a crawlspace, pulling in aviation exhaust, or growing mold behind degraded fiberglass lining, we’ll diagnose it with a camera, show you the footage, and quote the repair before any work begins. Call us at (844) 685-6342.

Call (844) 685-6342

Why Bellows Air Duct & Vent Co. Is San Bruno’s Preferred Duct Repair & Sealing Company

We’ve been serving San Bruno homeowners since 2012, long enough to have worked on the original duct systems in neighborhoods like Rollingwood, Lomita Park, and the Crestmoor area. Our technicians know which 1950s subdivisions have sheet-metal trunks with failing duct-board lining, which crawlspaces stay damp year-round from Gap moisture, and why standard sealing methods sometimes fail here.

San Bruno customers call us back because we answer the phone 24 hours a day with a live person, not an app or voicemail. Our background-checked, uniformed technicians arrive when we say they will, camera-inspect every duct run before touching a tool, and leave a written record of what was found and what was fixed. The price we quote over the phone is the price on the invoice. No bait coupons, no upsells at the door.

Our 90-Day Done Right Promise covers every repair: if something isn’t right, we return at no charge with no paperwork required. That guarantee has been non-negotiable for over 42 years.

Our Duct Repair & Sealing Services in San Bruno

Duct Sealing

Sealing in San Bruno requires more than slapping mastic on a joint and calling it done. The marine humidity that funnels through the San Bruno Gap keeps crawlspace and attic duct surfaces damp for months at a stretch, which means standard water-based mastic can fail prematurely, often within two years. We use professional-grade sealants rated for high-moisture environments, and we verify every seal with a pressure test and camera inspection. Our Duct Repair & Sealing team checks for the greasy, dark-grey hydrocarbon film we often find in homes under SFO departure paths - if that contamination is present, we clean the plenum before sealing so the mastic bonds to metal, not aviation residue.

Flex Duct Repair

Flex duct installed during later furnace upgrades is common in San Bruno’s older homes, and it’s often the first thing to fail. Moisture from the Gap climate condenses on the inner liner, adding weight that causes sagging or kinking in crawlspaces. A kinked flex duct doesn’t just leak - it can collapse entirely, sending all your heated air into the dirt beneath the house. We replace compromised sections with properly supported, insulated flex duct and seal all connections with mastic and mechanical fasteners. We repaired a flex-duct run in a 1950s home on Elm Avenue where the original duct-board lining had delaminated, allowing humid air from the crawlspace to condense inside the supply trunk. We cut out the compromised section, replaced it with insulated flex duct, and sealed all joints with mastic to prevent the re-entry of aviation-exhaust particulates that had been accumulating for decades.

Metal Duct Repair

The original sheet-metal duct runs in San Bruno’s post-WWII homes were built to last, but the fiberglass duct-board lining inside them wasn’t. After 60-70 years, that lining degrades, sheds fibers into your air stream, and creates a porous surface where mold and biofilm colonize - especially given the combination of Gap humidity and SFO particulates. Spot repair isn’t always possible. Sometimes we can reline a section; sometimes the corrosion and contamination are extensive enough that a partial retrofit makes more sense. We’ll show you the camera footage and explain both options with real numbers before you decide.

Duct Insulation

Uninsulated or damaged duct insulation in San Bruno is a double problem. The damp crawlspace air cools the metal surface, causing condensation that drips onto subflooring and promotes mold. Meanwhile, you’re paying to heat air that loses temperature before it reaches your vents. We install foil-faced fiberglass insulation or closed-cell foam wraps rated for marine climates, sealed at all seams to keep moisture out and conditioned air in.

Trusted Brands We Service in San Bruno

We carry parts and materials from Rotobrush, Nikro, and Abatement Technologies - the same brands serious HVAC contractors specify for commercial jobs. For San Bruno homeowners, that means we don’t wait on special orders for most repairs. If your duct system needs a custom fabricated fitting for an odd-sized 1950s trunk line, we can often build it on the truck and complete the job in a single visit. No return trips, no living with a hole in your system overnight.

Common Duct Repair & Sealing Problems We See in San Bruno Homes

• Mastic seals failing within two years. The persistent humidity from the San Bruno Gap keeps duct surfaces damp enough that standard sealants lose adhesion. We see this most often in crawlspace joints on the bay-facing slopes where fog lingers longest.
• Original fiberglass duct-board lining shedding fibers. Those 1940s-1960s tract homes weren’t built with air conditioning, so decades of heating-only cycles let debris accumulate while the lining slowly degraded. The result is a duct that moves air through a deteriorating filter made of its own walls.
• Flex ducts sagging or kinking from moisture weight. Upgraded flex runs in damp crawlspaces absorb atmospheric moisture, get heavy, and pull away from supports. The kink blocks airflow; the sag creates a low point where condensation pools.
• Aviation-exhaust particulate buildup in supply plenums. Homes under the SFO flight path, particularly east of El Camino Real, develop a distinctive dark-grey greasy film that resists standard dry-brush cleaning and can interfere with sealant adhesion if not addressed first.

Air Duct Cleaning in San Bruno, Built on the K.E.Y.S. Code

The Bay Area’s mix of salt air, redwood pollen, and decades-old ranchers with original ductwork means your system works harder than it should. We inspect with a camera before we touch a thing, clean to the collar, and show you after. Dryer vents get cleared to code, because lint fires are real and preventable. One honest price, no surprises on the bill. we coordinate through our San Francisco Bay Area service area

We stand behind it with the Keystone Standard: 90 days, in writing, no arguing. Named for the oldest air-moving tool there is. Clean air, the old craft way.

Pricing for Duct Repair & Sealing in San Bruno, CA

We Also Serve Cities Near San Bruno

Our San Bruno crew regularly works in Millbrae, South San Francisco, Pacifica, and Burlingame. The same flight-path and Gap-humidity conditions affect homes in eastern Millbrae and northern Burlingame, while Pacifica’s direct coastal exposure brings its own duct corrosion patterns. Wherever you are on the mid-Peninsula, we bring the same camera inspection, upfront pricing, and 90-Day Done Right Promise.

FAQs - Duct Repair & Sealing in San Bruno