Whole-system duct and dryer vent check with before-and-after photos - you see exactly what came out of your vents
That "$99 whole-house special" is a bait ad - the real number appears once they are in your hallway, or the "clean" is a shop-vac at the register. We photograph the inside of your ducts before and after instead.
Before
After
Before
After
Before
AfterFast, Reliable Duct Sealing Across Millbrae
Millbrae homeowners deal with a problem most Bay Area duct companies never mention: the kerosene odor that drifts indoors when winter winds blow from SFO. We’re the Duct Sealing crew that knows why it happens and how to stop it at the source. Our technicians are dispatched from the San Francisco Bay Area office and serve Millbrae directly, arriving inside the quoted window with written pricing in hand. If your registers carry that telltale jet-fuel smell, or if your energy bills have climbed without explanation, call (361) 326-5060. We’ll inspect the seams, show you what the camera sees, and seal what actually needs sealing.
Why Hollis Air Duct Cleaning Is Millbrae’s Preferred Duct Sealing Company
We’ve been working in Millbrae long enough to recognize the housing patterns: the post-WWII ranches off El Camino Real, the 1960s tracts near Mills High School, the original galvanized steel ductwork that still runs through most of them. That local knowledge matters because sealing ducts in a 1954 ranch with corroded trunk lines is different work than sealing flex duct in a newer build.
Our technicians are background-checked, uniformed, and held to The Garrison Code: arrive inside the window, price in writing before touching anything, leave the site clean. Every duct sealing job in Millbrae carries our 365-Day Done Right Promise in writing. If the seal fails or the smell returns within a year, we come back and make it right at no charge, including a free second visit.
Phones are answered by a live person 24 hours a day, 7 days a week. No voicemail loops. No callback queues.
Air Duct Sealing in Millbrae
Air Duct Sealing in Millbrae means closing the gaps in your supply and return ductwork so conditioned air reaches your rooms and contaminated outdoor air stays outside. In this city, the work is especially critical because of what sits outside: SFO’s flight path deposits jet exhaust, tire rubber particulates, and kerosene byproducts that get pulled straight into loose duct seams when the wind shifts. A typical Air Duct Sealing job in Millbrae runs $450 – $850 for a single system, depending on how many joints need mastic and mesh, whether the air handler cabinet requires sealing, and how accessible the trunk lines are in your crawl space or attic.
What We Seal and What We Skip
We seal supply and return joints, register boots, and air handler cabinets with duct mastic and fiberglass mesh, not tape that dries and falls off. We do not seal over damp or microbially active surfaces. Fog-damp galvanized steel needs to be dry and clean first, or the mold simply grows behind the sealant.
Camera Verification
We run a borescope before and after. You see the corroded seams. You see the sealed joints. No guesswork, no “trust us” handoff.
Duct Sealing Services in Millbrae
Duct Sealing Services in Millbrae cover the full range of joint and seam closure work for residential HVAC systems, from spot repairs on disconnected flex runs to complete trunk-line sealing in older homes with original galvanized steel. Most Millbrae homeowners call us after noticing uneven heating, rising Pacific Gas & Electric bills, or that distinct kerosene odor during fall and winter wind shifts. Duct Sealing Services in Millbrae typically range from $450 for targeted spot sealing to $1,200 for whole-system trunk and air handler cabinet work in larger homes with multiple zones.
Source Removal Before Sealing
We do not seal over dirty ducts. Our Duct Sealing Services include negative-air source removal with HEPA filtration if needed, using Nikro negative-air machines and Rotobrush rotary systems to clear debris before mastic goes on.
The Air Handler Cabinet
Millbrae’s marine fog condenses on blower motors and pulls damp air through loose panel seams. We seal those too. Most companies ignore the cabinet entirely.
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 Millbrae
We stock sealing materials and filtration components from Aprilaire, Abatement Technologies, and Guardsman, the same brands commercial HVAC crews specify. For Millbrae homeowners, that means no waiting on special orders when your system needs a new filter rack seal or an upgraded return-air gasket. Our vans carry mastic, fiberglass mesh, and foil tape rated for the temperature swings your attic sees. We also work with Honeywell and Aprilaire filtration upgrades when sealing reveals your return system is pulling in more SFO-area particulate than your current filter can catch.
Common Duct Sealing Problems We See in Millbrae Homes
- Kerosene odor through registers during wind shifts. Jet exhaust from SFO gets drawn into return-side seams that have loosened over decades. Sealing the return trunk and air handler cabinet stops it. Masking it with air fresheners or “sanitizing fog” does not.
- Mold regrowth behind fresh mastic. Millbrae’s morning fog and high humidity keep galvanized steel damp. Seal over that moisture and mold grows behind the mastic within a season. We dry and treat first.
- Disconnected flex runs in crawl spaces. The older ranches near Millbrae Avenue often have sagging flex duct that pulled loose from register boots. We reconnect and seal with proper supports so it stays put.
- Corroded galvanized trunk lines. Original steel ducts from the 1950s-70s develop pinholes and seam gaps. We assess whether spot sealing suffices or if section replacement is the honest recommendation.
Pricing for Duct Sealing in Millbrae, CA
A typical duct sealing job in Millbrae runs $450 – $850 for a single HVAC system with standard accessibility. Whole-system sealing in larger homes with multiple zones or difficult crawl-space access can reach $1,000 – $1,200. What moves the price: how many linear feet of trunk need mastic, whether the air handler cabinet requires sealing, if we need to perform source removal first, and how accessible your ductwork is. We give you a written price before any work starts. That price does not move at the door. No per-vent add-ons, no “we found another problem” upsells. Call (361) 326-5060 for a free estimate. We’ll inspect your system, show you camera footage of the seams, and quote the exact work.
We Also Serve Cities Near Millbrae
Our crews work throughout the mid-Peninsula. We provide Duct Sealing in Millbrae and also serve San Bruno, Burlingame, South San Francisco, and Pacifica. Same written pricing, same 365-Day Done Right Promise, same live-answer phones in every service area.
Serving Millbrae, CA - Our Local Coverage Area
We’re based in the Millbrae 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 About Duct Sealing in Millbrae
Yes, if the odor is entering through loose return duct seams or an unsealed air handler cabinet, which is the most common path in Millbrae homes under SFO’s flight path. We verify this with a camera inspection before sealing. Call (361) 326-5060 to schedule.
No. Fogging masks odor temporarily but does not remove the particulate load that jet exhaust deposits in your ducts. Source removal with negative-air equipment and HEPA filtration, followed by physical sealing of the seams, is what actually stops the contamination cycle.
Often yes, if the metal is structurally sound and the seams are accessible. We camera-inspect first. If corrosion has perforated the trunk line, we’ll tell you honestly that section replacement makes more sense than sealing pinholes.
The constant moisture accelerates corrosion in galvanized steel and promotes microbial growth on damp surfaces. Homes without proper attic or crawl-space ventilation see these problems sooner. We check for condensation sources as part of every sealing evaluation.
Yes. The blower cabinet is where Millbrae’s humidity condenses and pulls damp outdoor air through loose panel seams. Sealing the trunk lines but ignoring the cabinet leaves a major leak path open. We include cabinet sealing in our whole-system scope.
Written by Roy Castellanos, Owner at Hollis Air Duct Cleaning, serving Millbrae since 2004.