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 Duarte
We seal ducts in Duarte homes where the real problem isn’t always dirt, it’s air leaking into the attic before it ever reaches the rooms you’re paying to cool. Our crews work the foothill neighborhoods from Encanto Parkway to the lower slopes near Huntingdon Drive, and we dispatch from our Los Angeles office with scheduling windows we actually keep. Most Duarte calls get a technician out within a few business days, and every job starts with a written price that doesn’t move once we’re inside. If your back bedrooms run warm, your energy bill climbs every August, or you feel weak airflow at the register, call us at (361) 326-5060. We’ll inspect the system, show you what we find, and quote the sealing work before we touch anything.
Why Hollis Air Duct Cleaning Is Duarte’s Preferred Duct Sealing Company
We’ve been in business since 2004 as part of the Garrison Partners family, and our Duct Sealing team knows the difference between a Duarte foothill ranch and a valley tract home. That matters because the duct failures we see here, up against the San Gabriel Mountains, aren’t the same patterns technicians find in Monrovia or Baldwin Park.
Our technicians are background-checked, uniformed, and held to The Garrison Code: arrive inside the window, price in writing, finish by the book, leave the site clean. Every repair carries our 365-Day Done Right Promise in writing. If the seal fails or the leak 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, seven days a week. No voicemail loops, no callback queues, no waiting until Monday to get on the schedule.
Roy Castellanos leads this operation, and our Duarte customers deal with the same crew standards we apply across every Garrison Partners location: written prices, written guarantees, and accountability you can verify.
Duct Repair in Duarte
Duct Repair in Duarte usually means fixing the damage that decades of foothill dust, Santa Ana winds, and thermal cycling have done to original galvanized and flex ductwork in 1950s-1970s ranch homes. We find separated trunk joints, crushed collars at takeoffs, and flex runs chewed by rodents or torn on attic framing. A typical duct repair in Duarte runs $280 – $650 depending on how many runs need attention and whether we can access them through the attic or need to open a soffit. We always inspect with a camera first, show you the footage, and write the price before we cut or seal anything.
Disconnected Flex Runs and Crushed Collars
The most common duct repair we make in Duarte older homes is reconnecting flex duct that has pulled free from its collar or sealing a crushed takeoff that has been blowing conditioned air into the attic for years. Our field vignette: on a 1962 ranch off Encanto Parkway, up against the foothills, a homeowner called us because the back bedrooms ran warm all summer; our tech pulled the air handler panel and ran a camera inspection on the supply and return ducts, finding three disconnected flex runs and a crushed collar at the first takeoff that had been blowing conditioned air into the attic for years. We did source removal with agitation tools under negative pressure and HEPA filtration, then sealed the collar, reconnected the runs, and mastic-sealed the plenum seams. The supply registers in those bedrooms finally read within a couple degrees of the thermostat.
Galvanized Trunk Joint Separation
Original galvanized steel trunk lines in Duarte’s mid-century ranches dry out and separate at the joints after decades of expansion and contraction. Tape falls off, gaps open, and your conditioned air leaks into the attic before it reaches the registers. We seal these with mastic and mechanical fasteners, not duct tape, because tape fails again within a season under attic heat.
Air Duct Sealing in Duarte
Air Duct Sealing in Duarte is the service that fixes the leaks cleaning alone cannot solve. We seal with mastic compound and reinforced mesh at joints, plenum seams, and register boots, then pressure-test the system to verify the seal holds. A typical air duct sealing job in Duarte runs $450 – $980 for a single-system home, with larger homes or multiple zones running higher. We use professional-grade sealing materials, not hardware-store tape, and we show you the before-and-after pressure readings so you know the work mattered.
Mastic Sealing at Joints and Plenums
Mastic is a thick, flexible compound we brush onto duct joints and seams. It stays pliable through decades of temperature swings, which matters in Duarte attics that hit 140°F in August. We apply it over fiberglass mesh for reinforcement, then let it cure before we pressurize the system and check our work.
Pressure Testing and Verification
After we seal, we run a duct blaster or static pressure test to measure leakage. If the system still leaks above industry standard, we find the missed joint and reseal. You get the numbers in writing, not a handshake and a promise.
Trusted Brands We Service in Duarte
We carry professional-grade equipment and materials on every Duarte job, including Rotobrush rotary brush systems for agitation cleaning, Nikro negative-air machines for controlled debris removal, and sealing and filtration products from Abatement Technologies and Guardsman. These are the same tools commercial crews use in hospitals and schools, not the hardware-store vacuums some competitors haul around. Because we stock common duct diameters, collar sizes, and mastic compounds locally, most Duarte repairs don’t wait on parts. If your system uses Honeywell or Aprilaire filtration components, we can source and install those during the same visit.
Common Duct Sealing Problems We See in Duarte Homes
- Original galvanized trunk joints dry and separate after decades of thermal cycling. The metal expands every summer and contracts every winter, and the original sealant or tape gives up. We find gaps at the trunk-to-branch connections that have been leaking for years, sometimes since the Nixon administration.
- Foothill-adjacent attic flex duct disconnects are easy to misdiagnose as a dirty-system problem. After a Santa Ana event or a canyon fire, ash fills the plenum and the run looks clogged when the real fault is a separated collar. We camera every suspicious run before we quote cleaning or sealing, because treating a disconnection with a brush pass wastes your money.
- Rodent and pest debris in accessible attic runs puncture flex and open small tears. Duarte’s older homes with attic access points invite squirrels, roof rats, and raccoons that chew or crush flex duct. Cleaning removes the debris but doesn’t close the hole. Those runs need sealing or replacement, or the leak returns within a season.
- Crushed collars at first takeoffs waste the most energy. The transition from rigid trunk to flex duct gets stepped on, hung wrong, or collapsed by storage items in the attic. Conditioned air dumps into the insulation instead of the bedroom register, and the homeowner cranks the thermostat lower to compensate.
Pricing for Duct Sealing in Duarte, CA
Duct sealing in Duarte typically costs $450 – $980 for a single-system home with accessible attic runs. Duct repair, when we need to replace crushed collars or reconnect separated runs, runs $280 – $650. Whole-system duct replacement on a mid-century ranch with original galvanized trunk lines can reach $2,200 – $4,500, though most Duarte homes don’t need full replacement if we catch the leaks early.
What moves the price: how many runs need sealing, whether the attic is accessible or we need to open soffits, and whether we find rodent damage that requires flex replacement before we can seal. We give one flat price per system, agreed in writing before work starts. No per-vent pricing, no add-ons at the door, no surprise charges because your attic was hotter than expected.
Every sealing job includes before-and-after photos of your own ducts, not stock images. You’ll see the separated joint, the sealed joint, and the pressure-test results. Call (361) 326-5060 for a free estimate. We’ll inspect the system, explain what we found, and write the price down before you decide.
We Also Serve Cities Near Duarte
Our crews work the full San Gabriel Valley foothill corridor. If you’re in Monrovia, Baldwin Park, Arcadia, or Azusa, the same scheduling, pricing, and guarantee standards apply. Dispatch and scheduling are coordinated from our Los Angeles office, and Duct Sealing in Duarte remains our focus for homeowners on the mountain-facing slope where the particulate load and duct conditions differ from what valley crews encounter.
Serving Duarte, CA - Our Local Coverage Area
We’re based in the Duarte 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 Duarte
Duarte’s housing stock sits directly against the San Gabriel Mountains foothills, so duct systems here collect an unusually heavy load of wind-blown mineral dust, oak and pine pollen, and wildfire ash funneled down from the Angeles National Forest canyons. That particulate load accelerates wear on original galvanized joints and flex duct collars, and the Santa Ana winds create pressure differentials that stress connections. Homes in lower-elevation cities like Baldwin Park face different air quality conditions and typically newer duct materials. Call (361) 326-5060 for an inspection if your registers show weak flow or your energy bill spikes every summer.
If your registers blow weakly, some rooms never reach thermostat temperature, or your energy bill climbs despite normal filter changes, you likely have leaks that cleaning won’t fix. We camera-inspect the system first and measure static pressure. High pressure with low airflow at the register means a leak; high pressure with normal airflow usually means blockage. We show you the footage and the numbers, then quote the right fix. Call (361) 326-5060 for a free estimate.
Duarte crews routinely pull visible ash and fine grit from return-air plenums and attic flex ducts in the foothill-adjacent neighborhoods after these events. The ash is finer than typical household dust and migrates through intake vents and any gap in the building envelope. If you smell smoke or see ash on your filter after a wind event, schedule an inspection. We may find the ducts need cleaning, sealing, or both if the pressure surge separated a collar. Call (361) 326-5060 and we’ll check it.
We access the attic, inspect every trunk joint and flex connection with a camera, clean debris with rotary brushes under negative pressure and HEPA filtration, then brush mastic compound onto every joint, seam, and register boot. We reinforce with mesh at high-stress points, reconnect any separated runs, and pressure-test the sealed system. A typical 1,200-square-foot ranch takes four to six hours. You get photos, pressure readings, and a written 365-Day Done Right Promise. Call (361) 326-5060 to schedule.
The EPA has found that indoor air can be two to five times more polluted than outdoor air, and in Duarte that pollution includes mountain-sourced particulates that lower-elevation cities don’t face in the same concentration. Wildfire ash, mineral dust, and oak pollen enter through leaks in the duct system, bypassing your filter entirely. Sealing those leaks keeps the particulate outside your breathing air and forces all intake through your filtration system where it belongs. Call (361) 326-5060 for an inspection and we’ll show you where your system is pulling unfiltered air.
Written by Roy Castellanos, Owner at Hollis Air Duct Cleaning, serving Duarte since 2004.