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 Palo Alto
Duct sealing in Palo Alto typically runs $800 – $2,400 for a whole-house job, depending on whether we’re patching accessible joints in a crawlspace or re-routing crushed runs in a mid-century retrofit. Most Palo Alto homes we work on need the full treatment: sealing, reinsulating, and often reconfiguring ductwork that was never sized for modern equipment. Call (361) 326-5060 for a written estimate before any work starts.
We’ve been crawling through Palo Alto attics and crawlspaces since 2004, and the housing stock here is unlike anywhere else in the Bay Area. From the Eichler tracts in Greenmeadow to the Craftsman bungalows south of University Avenue, you’re dealing with legacy systems that out-of-town crews misread. Our dispatch runs out of the San Francisco Bay Area office, so crews serving Palo Alto know the local building department’s requirements and the specific headaches these older homes present. That matters when your ductwork runs through a 14-inch crawlspace above a radiant slab.
Why Hollis Air Duct Cleaning Is Palo Alto’s Preferred Duct Sealing Company
Palo Alto homeowners don’t call us because we’re the cheapest. They call because they’re tired of estimates that balloon once the technician is inside. Every Hollis job starts with a written price that doesn’t move at the door. Our Duct Sealing team arrives uniformed, background-checked, and on time, inside the window we quoted.
We know the local terrain. In Old Palo Alto, we’ve sealed ducts in 1920s Spanish Revival homes where the original gravity furnace was replaced with forced air in the 1970s, leaving a mismatch of duct sizes and materials. In Professorville, we’ve found asbestos-wrapped supply runs that needed careful abatement before sealing could begin. This isn’t theoretical. We’ve got the photos, the mastic receipts, and the static-pressure readings to prove what changed.
Our 365-Day Done Right Promise applies to every Palo Alto job in writing. If the seal fails, if a joint opens, if the blower motor starts fighting leaks again within a year, we come back and make it right at no charge. No negotiation, no “let us check the notes.” The Garrison Standard means what it says.
Duct Insulation in Palo Alto
Duct Insulation in Palo Alto is often the missing half of the sealing equation. You can seal every joint with mastic and foil tape, but if your supply runs sit uninsulated in a ventilated crawlspace, you’re still losing conditioned air and pulling in whatever’s outside. In Palo Alto’s mild climate, that outside air carries oak pollen in spring, crawlspace dust year-round, and enough moisture during winter rains to degrade fiberboard ductwork from the outside in.
Most Palo Alto homes we insulate fall in the $1,200 – $2,800 range for full duct sealing plus insulation wrap or replacement. Eichler add-on systems with only two or three short runs might run $600 – $1,100. We price by the system, not by the linear foot, and we write it down before we touch anything.
When Uninsulated Ducts Waste Energy
In Greenmeadow and the Green Gables neighborhood, we regularly find wall-furnace supply ducts that were never insulated when installed in the 1980s or 1990s. The metal runs sweat in winter, grow mold in the crawlspace, and lose 15 – 25% of their heat before the air reaches the register. Wrapping those runs with formaldehyde-free fiberglass and sealing the vapor barrier stops the losses and the microbial growth.
Radiant-Slab Homes Need Different Thinking
Eichler owners often assume duct insulation doesn’t apply to them. If you’ve got add-on ducts feeding a evaporative cooler or a high-velocity mini-duct system, it absolutely does. Those runs are typically the only ductwork in the house, and they’re usually the worst insulated because they were installed as an afterthought.
HVAC Duct Sealing in Palo Alto
HVAC Duct Sealing in Palo Alto means fixing the leaks that make your blower motor work harder, your rooms heat unevenly, and your energy bills climb despite the mild climate. We use mastic compound and mechanical fasteners for permanent joints, foil tape from Guardsman for temporary access points, and negative-air verification to confirm the seal held. A typical whole-house HVAC duct sealing job in Palo Alto runs $1,000 – $2,400, with simpler crawlspace-access repairs at $800 – $1,500.
The real question in Palo Alto isn’t whether your ducts leak. They do. We’ve tested hundreds of local systems; the average leakage rate in pre-1990 homes is 25 – 35% of total airflow. The question is where the leaks are and whether sealing alone will fix the underlying problem.
Static Pressure Testing Before and After
Every HVAC duct sealing job we complete in Palo Alto includes pre- and post-sealing static pressure readings. If the pressure doesn’t drop after sealing, the leaks weren’t the real problem. Often in Palo Alto’s older homes, the ducts are simply too small for the modern air handler, and no amount of mastic will fix that. We tell you before we start, not after we’ve charged you.
Source Removal Comes First
We don’t seal dirty ducts. In Palo Alto’s legacy homes, decades of accumulation coat the duct walls. Sealing over that traps the debris where the blower keeps recirculating it. Our rotary brush systems from Rotobrush and negative-air machines from Nikro clean the runs first. Then we seal. The order matters.
Trusted Brands We Service in Palo Alto
We stock parts and materials from Guardsman, Rotobrush, and Nikro for Palo Alto jobs, which means most repairs don’t wait on a warehouse run to San Jose. Guardsman foil tape and mastic handle the sealing work; Rotobrush rotary agitation tools clean before we seal; Nikro negative-air machines verify the job held. We also work with Honeywell and Aprilaire filtration products when the sealed system needs better air cleaning on the return side. For Eichler neighborhoods like Greenmeadow, where parts availability can delay out-of-town crews, our local inventory means we finish what we started on the same visit.
Common Duct Sealing Problems We See in Palo Alto Homes
- Crushed runs in shallow crawlspaces. In Greenmeadow Eichlers, add-on ducts were often routed through 12-inch crawlspaces above radiant slabs, where decades of settling joists or careless storage have flattened the flex duct against the framing. Sealing the joints won’t restore airflow; we re-route or replace the crushed sections.
- Fiberglass particle infiltration from exposed batts. In Palo Alto’s older crawlspaces, the return plenum often sits inches from unwrapped fiberglass insulation. Negative pressure pulls those particles straight into the air handler. We seal the plenum, box it with rigid duct board, and verify with camera inspection.
- Original ductwork undersized for modern equipment. A 1970s retrofit in an Old Palo Alto Craftsman might have 6-inch supply runs feeding a 3-ton air handler installed in 2015. The static pressure reads high, the blower screams, and the upstairs rooms never cool. Sealing helps; resizing fixes it. We quote both.
- Disconnected joints from thermal cycling. Palo Alto’s dry summers and wet winters mean metal ducts expand and contract more than in consistently hot climates. Tape dries out, joints separate, and conditioned air dumps into the attic. We find these with blower-door-directed infrared, then seal with mastic that flexes.
Pricing for Duct Sealing in Palo Alto, CA
A typical whole-house duct sealing job in Palo Alto runs $1,000 – $2,400. Smaller Eichler add-on systems with two to four runs run $600 – $1,100. Duct sealing plus full insulation wrap or replacement runs $1,200 – $2,800. What moves the price: accessibility (crawlspace height, attic hatch location), extent of damage (crushed runs cost more than loose joints), whether cleaning is needed first, and whether the ductwork is properly sized for the equipment.
We don’t quote per-vent or per-linear-foot. That’s the bait-and-switch game. We quote one flat price per system, agreed in writing before work starts. The price on the paper is the price at the door. Free estimates; call (361) 326-5060 to schedule.
We Also Serve Cities Near Palo Alto
Our crews work throughout the mid-Peninsula. We regularly handle Duct Sealing in Palo Alto and neighboring Stanford, Menlo Park, Atherton, and Los Altos. Each city has its own housing stock and its own duct problems; we adjust our approach to what we find, not to a one-size-fits-all checklist.
Serving Palo Alto, CA - Our Local Coverage Area
We’re based in the Palo Alto 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 Palo Alto
It depends on whether you have add-on ducts. Many Eichler and Eichler-style homes in Greenmeadow and Green Gables were built with radiant slabs and no central ducts, but later got wall furnaces or evaporative coolers with short duct runs. Those add-on ducts are often the leakiest, most poorly insulated in any Palo Alto home because they were installed as afterthoughts. We inspect first; if you have no ductwork, we’ll tell you. Call (361) 326-5060 for a free check.
Because sealing over decades of accumulated dust traps debris against the duct walls where the blower keeps recirculating it. In Palo Alto’s legacy homes, we regularly find 30 – 40 years of accumulation in original ductwork. Our Rotobrush and Nikro systems remove that source first. Then we seal. The order isn’t negotiable if you want the job done right.
Disconnected joints, crushed flex runs, and return plenums pulling fiberglass particles off exposed crawlspace batts. In a 1962 Eichler in Greenmeadow, we found two supply runs crushed flat against joists and a return box drawing air straight through unwrapped insulation. We sealed the runs, reinsulated the boxes with Guardsman foil tape and mastic, and verified the static pressure dropped back into spec. Out-of-town crews often miss these hybrid radiant-slab setups entirely.
Sometimes both, in stages. Sealing fixes leakage; replacement fixes sizing. Original undersized duct runs in mid-century Palo Alto homes were never designed for modern forced-air equipment, so sealing alone won’t balance the system. We test static pressure before we quote. If the ducts are too small, we tell you, and we quote re-routing or replacement separately from sealing. No surprises after we’re inside.
Palo Alto’s mild, dry summers and wet winters mean HVAC systems run less year-round, so dust and allergens accumulate during long idle periods. Spring oak and redwood pollen infiltrates leaky ductwork, then the first hot day in May blasts it through the house. Sealing stops that infiltration. The climate also means thermal cycling: metal ducts expand in summer, contract in winter, and tape joints dry out faster than in consistently hot climates. We use mastic, not tape, for permanent seals.
Written by Roy Castellanos, Owner at Hollis Air Duct Cleaning, serving Palo Alto since 2004.