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 Lorenzo
Duct sealing in San Lorenzo typically costs $400 – $1,200 for a whole-home system, depending on access, the condition of existing runs, and whether asbestos-containing materials need abatement. Most San Lorenzo jobs are scheduled within a week and completed in a single day. Call (361) 326-5060 for a written estimate before any work starts.
We’ve been driving our vans to San Lorenzo since 2004, and we know the difference between a 1962 Eichler off Via Alamitos and a 1970s ranch near Lewelling Boulevard. The fog rolls in off the Bay, the attics stay damp, and the original ductwork tells a story we can read before we even climb the ladder. Our San Francisco Bay Area office dispatches crews to San Lorenzo daily, so you’re not waiting on a tech driving up from San Jose or across the bridge from the Peninsula.
San Lorenzo’s housing stock is honest, older, and built to a different standard. The ducts we find were never designed for modern filtration, and decades of marine-layer condensation have done what decades always do. We don’t sell you a system you don’t need. We seal what’s there, replace what we can’t save, and write the price down before we touch a tool.
Why Hollis Air Duct Cleaning Is San Lorenzo’s Preferred Duct Sealing Company
We’re part of the Garrison Partners family, and every Hollis location runs on The Garrison Standard: arrive inside the window, price in writing, do it by the book, leave the site clean. In San Lorenzo, that means showing up when we said we would, not leaving your Eichler’s crawl space tracked with mud, and explaining what we found in plain terms before we propose a fix.
Our technicians are background-checked and uniformed. You know who’s walking into your home before they arrive. And our phones are answered by a live person, 24 hours a day, 7 days a week. No voicemail loops. No “we’ll call you back Monday.”
The 365-Day Done Right Promise covers every duct sealing job we do in San Lorenzo. If the work fails within a year, we come back and make it right at no charge, including a free second visit. That’s written on every invoice, not implied over the phone.
We stock professional-grade equipment from Nikro, Honeywell, and Abatement Technologies, the same tools commercial crews use in hospitals and schools. For San Lorenzo’s older homes, that matters. You can’t seal a compromised 1950s trunk with hardware-store tape and hope it holds through another wet winter.
Duct Repair in San Lorenzo
Duct Repair in San Lorenzo means fixing the physical damage that sealing alone won’t solve: disconnected runs in shallow-pitch attics, crushed flex duct behind knee walls, and sheet-metal trunks corroded by decades of fog-belt condensation. We see this most often in the Eichler tracts and 1960s ranches between Via Alamitos and Lewelling Boulevard, where original ductwork has simply reached the end of its service life. A typical duct repair in San Lorenzo runs $300 – $800 for spot fixes, or $1,000 – $2,500 if we’re replacing a significant portion of the system.
Disconnected Runs and Attic Access
San Lorenzo’s low-clearance attics make physical inspection difficult. We use borescope cameras to find separations without tearing out drywall. When we do find a disconnected run, we reconnect with mechanical fasteners first, then seal with mastic rated for the temperature swings these attics see.
Corroded Trunks and Condensation Damage
The marine layer doesn’t just make mornings gray. It keeps attic surfaces damp for months, and sheet-metal trunks without proper insulation sweat themselves into rust. We replace compromised sections with galvanized metal or insulated flex, depending on the routing constraints of your specific home.
Air Duct Sealing in San Lorenzo
Air Duct Sealing in San Lorenzo addresses the leakage points that make your HVAC system work harder than it should: gaps at plenum connections, loose joints in flex duct, and deteriorated tape at trunk branches. In San Lorenzo’s climate, sealing is rarely a simple matter of applying mastic. The substrate has to be dry, the joint has to be structurally sound, and any legacy asbestos tape has to be handled per abatement standards. Whole-home air duct sealing in San Lorenzo typically runs $400 – $1,200, with most single-story ranch jobs falling in the $600 – $900 range.
Negative-Pressure Sealing Protocol
We pressurize the duct system and apply sealant under controlled conditions. This lets us verify the seal in real time, not guess at it. For San Lorenzo’s older homes, this step is critical. Aerosol sealant slapped over wet, fog-condensed joints fails within a season. We dry first, seal second, test third.
Asbestos Tape Assessment
Original 1950s duct wrap in Eichler neighborhoods often contains asbestos tape. Sealing over it without proper handling traps a legacy hazard. Our techs identify this material during camera inspection and coordinate abatement-qualified handling before any sealant touches the joint. It’s slower. It’s the only way to do it safely.
Trusted Brands We Service in San Lorenzo
We carry parts and filtration products from Honeywell, Aprilaire, and Abatement Technologies, brands we specify because they hold up in the conditions San Lorenzo attics actually present. Honeywell media filters handle the fine particulate that fog-belt mold spores and wildfire ash produce. Aprilaire humidistat controls help manage the moisture loads that degrade duct joints in the first place. We stock common fittings and sealants locally, so a San Lorenzo job doesn’t wait on a parts run to a warehouse across the Bay. Our Nikro negative-air machines and rotary brush systems are the same units commercial crews run in schools and medical buildings. We don’t bring less to a residential job. The Garrison Standard doesn’t work that way.
Common Duct Sealing Problems We See in San Lorenzo Homes
- Fog-belt condensation rotting flex joints. San Lorenzo’s cool, damp summers keep attic duct surfaces wet for months. The original vinyl or cloth-backed tape loses adhesion, the flex duct pulls away from the collar, and your conditioned air leaks into the attic before it reaches the register. We find this in nearly every pre-1970s home we inspect.
- Asbestos tape crumbling at trunk branches. In the Eichler tracts off Via Alamitos, the white wrap on original sheet-metal ducts is often asbestos-containing duct tape. It was standard practice in 1958. Now it’s friable, and any disturbance requires abatement protocol. We identify it, handle it correctly, and seal only after the hazard is managed.
- Crushed flex runs hidden behind attic knee walls. San Lorenzo’s shallow-pitch roofs leave little maneuvering room. Installers from decades past folded flex duct to make it fit, and those kinks remain in place until a camera finds them. Sealing the visible joints doesn’t help if half the air is blocked by a crushed run we never saw.
- Wildfire ash and mold spore accumulation degrading seals. The East Bay hills fires of recent years sent fine ash through attic vents, and the marine layer keeps mold viable year-round. This debris collects at duct joints, preventing proper sealant adhesion. We clean before we seal. Every time.
Pricing for Duct Sealing in San Lorenzo, CA
A typical whole-home duct sealing in San Lorenzo runs $400 – $1,200. Single-story ranch homes with accessible attics usually fall at the lower end, around $600 – $900. Eichler homes with shallow-pitch roofs, asbestos tape abatement needs, or significant disconnection repair push toward $1,000 – $1,500. We do not quote per-vent prices. We price per system, in writing, before any work begins.
What moves the number: the linear feet of ductwork, the number of joints requiring attention, whether we need to coordinate asbestos abatement, and the physical access your attic allows. A crawl-through Eichler attic takes longer than a walk-up ranch. That’s not a surprise we spring at the door. We inspect, we measure, we write it down, and the price doesn’t move.
Estimates are free. Call (361) 326-5060 to schedule. We’ll give you a real number you can compare, not a teaser that doubles once the van is in your driveway.
We Also Serve Cities Near San Lorenzo
Our crews work throughout the East Bay, including San Lorenzo and neighboring Castro Valley, San Leandro, Union City, and Oakland. Dispatch and scheduling are coordinated from our San Francisco Bay Area office, with local technicians assigned to minimize drive time and keep appointments inside the quoted window. Whether you’re in the hills above Castro Valley or the flatlands near San Leandro’s Marina Boulevard, the same Duct Sealing standards apply: written price, background-checked tech, 365-Day Done Right Promise.
Serving San Lorenzo, CA - Our Local Coverage Area
We’re based in the San Lorenzo 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 Lorenzo
Eichler homes in San Lorenzo were built with uninsulated attics, original sheet-metal or early flex duct, and no provision for the humidity control modern HVAC expects. The fog-belt condensation these attics collect rots joints and loosens asbestos tape that newer homes never had. Sealing isn’t just efficiency here. It’s often the difference between conditioned air reaching your rooms and bleeding into the attic. Call (361) 326-5060 for a free inspection and written estimate.
Yes, but not by sealing over the tape. We identify asbestos-containing materials during camera inspection, coordinate abatement-qualified handling per NADCA standards, and seal only after the hazard is properly managed. This adds steps and cost, but it’s the only safe approach for San Lorenzo’s 1950s-era ductwork. We’ll explain exactly what we found and what it requires before any work starts.
The marine layer keeps attic surfaces damp for much of the year, which prevents sealant from bonding properly to wet or condensed substrates. Aerosol or mastic sealant applied over fog-belt-moistened joints fails within a season because the underlying material never dried. We dry ducts thoroughly before sealing, using heated negative-air flow when necessary. San Lorenzo’s climate demands this step. Skipping it is why cheap seals don’t last.
Yes. Fine ash from East Bay hills fires and mold spores from persistent dampness accumulate at duct joints, creating a barrier that sealant can’t penetrate. We clean these surfaces with rotary brush systems and negative-air extraction before applying any sealant. A seal is only as good as the surface it bonds to. In San Lorenzo, that surface is rarely clean enough without pre-treatment.
Whistling registers usually mean high static pressure from duct leakage or blockage, not the register itself. In San Lorenzo’s 1960s ranches, we find disconnected runs, crushed flex behind knee walls, or gaps at the plenum that force air through the remaining openings faster than designed. Sealing the leaks and reconnecting separated runs drops the static pressure back into range. The whistle stops because the system breathes properly again. Call (361) 326-5060 and we’ll find the source.
Ready to stop losing conditioned air to your attic? Call Hollis Air Duct Cleaning at (361) 326-5060 for a free, written estimate on duct sealing in San Lorenzo. We’ll inspect your system, explain what we found in plain terms, and give you one flat price per system before any work begins. No per-vent pricing. No surprises at the door. Just The Garrison Standard, backed by our 365-Day Done Right Promise.
Written by Roy Castellanos, Owner at Hollis Air Duct Cleaning, serving San Lorenzo since 2004.