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.
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AfterFast, Reliable Duct Sealing Across San Francisco
Duct sealing in San Francisco typically costs $800 – $2,400 for a whole-home system, depending on whether we’re sealing accessible metal ductwork or addressing the joist-cavity returns common in pre-war housing. Most jobs take one day, and we provide a written price before any work starts. Call (361) 326-5060 for a free estimate.
We’ve been working in San Francisco homes long enough to know the difference between a standard duct-wrap job and what this city’s housing stock actually demands. Our crews serve San Francisco from our Bay Area dispatch office, and we regularly handle calls from the Richmond District down to Bernal Heights, across to the Sunset, and up through the Mission. The fog, the salt air, and the century-old framing aren’t quirks here. They’re the baseline we plan for.
San Francisco’s homes weren’t built for modern HVAC. Gravity furnaces from the 1920s and 1930s, shared wall chases in attached row houses, and ductwork that has never been retrofitted for filtration or sealing – these are what we find on most jobs. Our Duct Sealing team treats every house as its own puzzle, because in this city, they always are.
Why Hollis Air Duct Cleaning Is San Francisco’s Preferred Duct Sealing Company
Hollis Air Duct Cleaning, founded in 2004 as part of the Garrison Partners family, brings written prices, background-checked uniformed technicians, and the 365-Day Done Right Promise to every San Francisco job. That promise means if our sealing work fails within a year, we return and make it right at no charge, including a free second visit. It’s in writing on every invoice.
Our San Francisco Bay Area office coordinates dispatch and scheduling locally, so crews arrive inside the quoted window. We don’t subcontract to random vans. Our technicians carry professional-grade equipment from Rotobrush, Nikro, and Abatement Technologies, and they follow The Garrison Standard: price in writing before work starts, complete the job by the book, leave the site clean.
Phones are answered by a live person 24 hours a day, 7 days a week. No voicemail loops. No callback queues. When a Richmond District homeowner called at 6 a.m. about a musty smell after a week of fog, we had a crew there that afternoon.
Duct Repair in San Francisco
Duct Repair in San Francisco almost always means fixing what decades of Pacific marine air and original galvanized steel have destroyed. We find corroded seams, crushed flexible duct runs from botched renovations, and disconnected branches in attic-less roof cavities that have never been inspected. A typical duct repair in San Francisco runs $400 – $1,200 for accessible supply runs, but jobs involving joist-cavity returns or shared chases in attached housing can reach $1,800 – $2,800.
Corroded Galvanized Supply Runs
The zinc coating on original 1920s – 1940s ductwork flakes off after years of salt-fog exposure. We cut out the damaged section, fabricate a replacement from matching gauge steel, and seal with foil-backed butyl tape rated for damp environments. Standard mastic won’t bond to pitted metal; we learned that the hard way on early jobs.
Disconnected or Crushed Flexible Duct
Retrofit flex duct from the 1970s and 1980s often sags in San Francisco’s tight crawlspaces or gets crushed by storage in basement areas. We replace with properly supported modern flex or rigid metal where space allows, then pressure-test the repair before we leave.
Air Duct Sealing in San Francisco
Air Duct Sealing in San Francisco is rarely the simple wrap-and-mastic job shown in suburban marketing. In the Sunset and Richmond districts, return-air paths are often open floor joist cavities rather than metal ducts, so sealing means addressing the building’s structural framing, not just the ductwork. A typical whole-system sealing job in San Francisco runs $800 – $2,400, with simpler supply-only work at the lower end and full joist-cavity encapsulation at the upper end.
Joist-Cavity Return Sealing
When your return path is the space between floor joists, every seam in the subfloor and every plumbing penetration becomes a leak point. We line these cavities with rigid board insulation and seal all edges with fire-rated caulk and metal tape, turning structural framing into actual ductwork. It’s labor-intensive. It’s necessary. And it’s specific to pre-war housing stock like San Francisco’s.
Mastic Sealing of Metal Trunks and Plenums
For intact metal ductwork, we brush-apply water-based duct mastic at all joints, seams, and register boots. At the air handler plenum, we use reinforced mesh tape embedded in mastic for a permanent seal that won’t crack with thermal cycling. We photograph before and after so you see what was done.
Trusted Brands We Service in San Francisco
Our San Francisco crews carry equipment from Rotobrush, Nikro, and Abatement Technologies – the same rotary brush systems, negative-air machines, and HEPA filtration units used in commercial buildings. For sealing materials, we stock foil-backed butyl tape, water-based duct mastic, and rigid board insulation from Honeywell and Guardsman product lines. We keep common sizes and materials on our vans to avoid delay. If your system uses an unusual register boot or plenum configuration common in Edwardian or Victorian housing, we fabricate custom fittings in our shop rather than ordering and waiting.
Common Duct Sealing Problems We See in San Francisco Homes
- Sealing only visible supply ducts while leaving joist-cavity returns open. This is common in Sunset and Richmond gravity-furnace homes. The supply side looks fine, but salty fog air still bypasses every seal through the open framing. We always inspect the return path before quoting.
- Standard mastic applied to corroded galvanized steel. Pacific marine air pits the metal surface; mastic bonds to rust flakes, not steel. The seal fails within a season. We grind or replace damaged sections first, then seal.
- Shared wall chases sealed without neighbor coordination. In attached row houses throughout the Mission and Bernal Heights, one unit’s duct chase serves multiple flats. Attempting to seal from one side leaves branches unsealed or damages neighboring connections. We coordinate access before we start.
- Attic-less roof cavities feeding damp air into the system. Many San Francisco homes have no true attic; ducts run through insulated roof cavities that breathe fog. We seal the cavity envelope, not just the duct, when this is the source.
Pricing for Duct Sealing in San Francisco, CA
A typical whole-home duct sealing job in San Francisco runs $800 – $2,400. Supply-only sealing with accessible metal ductwork falls at the lower end, around $800 – $1,400. Jobs involving joist-cavity returns, shared chase coordination, or corroded-section replacement range from $1,600 – $2,400. Single register boot sealing or small repair starts around $250 – $450.
What moves the price: accessibility (crawlspace vs. basement vs. roof cavity), whether returns are actual ducts or open framing, extent of corrosion damage, and whether neighbor coordination is needed for shared chases. We inspect with a camera before quoting. The price we write down is the price you pay. No per-vent add-ons. No equipment fees that appear at the door.
Estimates are free. Call (361) 326-5060 to schedule.
We Also Serve Cities Near San Francisco
Our crews regularly work in San Francisco and the surrounding communities: Daly City to the south, Brisbane along the industrial corridor, Sausalito across the Golden Gate, and South San Francisco on the peninsula side. Same written prices, same 365-Day Done Right Promise, same live-answer phones.
Serving San Francisco, CA - Our Local Coverage Area
We’re based in the San Francisco 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 San Francisco
Edwardians in San Francisco typically have gravity-furnace systems with open joist-cavity returns, shared wall chases, and original galvanized steel corroded by decades of marine air. Sealing these requires addressing the building’s structural framing, not just wrapping metal ducts. Suburban homes with modern flex duct and dedicated return plenums are simpler jobs with lower labor hours. Call (361) 326-5060 for an exact quote on your house – estimates are free.
Yes, we seal gravity-furnace systems regularly in the Sunset District. The return path is usually the open floor joist cavity, which we line and seal to create a contained airway. We also seal supply registers and any accessible trunk lines. The gravity furnace itself isn’t the obstacle; the unconditioned framing acting as ductwork is. We inspect with a camera first, then quote in writing.
Sealing alone does not remove existing mold. We clean the affected duct runs first, typically with a rotary brush system and negative-air containment, then seal to prevent recurrence. The root cause is usually damp air entering through leaks in the duct envelope or building cavity; sealing stops the moisture source. In Bernal Heights, the combination of stucco exterior, uninsulated crawlspaces, and marine-layer humidity makes this pattern common. Call (361) 326-5060 and we’ll inspect for both cleaning and sealing needs.
Often yes, if your ducts share wall chases with adjacent units. In San Francisco’s attached housing, particularly in the Mission and Richmond districts, one chase may serve multiple flats. We can seal your branches from inside your unit, but full chase sealing requires access to neighboring spaces. We handle the coordination, explain the scope to all parties, and schedule accordingly. We don’t start work that leaves a job half-finished.
Signs of leakage include uneven heating between rooms, musty smells at registers, dust that returns quickly after cleaning, and higher-than-expected utility bills. Dirty ducts show visible debris at registers and reduced airflow. We use a camera inspection and pressure testing to distinguish the two. Many San Francisco homes have both problems; we quote each separately so you choose what to address. Call (361) 326-5060 to schedule an inspection.
Written by Roy Castellanos, Owner at Hollis Air Duct Cleaning, serving San Francisco since 2004.