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 Snohomish
We seal ducts in the Victorians along Avenue D, the hillside ranches above Blackman Lake, and the apartment blocks near the riverfront. Dispatch runs out of our Seattle office, but our crews live and work in Snohomish, so we know which streets flood in January and which crawlspaces stay damp year-round from river-valley fog. Most sealing jobs here run $450 – $1,200 for a typical single-family system, and we quote in writing before touching anything. Call (361) 326-5060 to schedule a free estimate.
Why Hollis Air Duct Cleaning Is Snohomish’s Preferred Duct Sealing Company
We’ve been part of the Garrison Partners family since 2004, and our Duct Sealing team has worked in Snohomish long enough to recognize the telltale signs of original gravity ducts before we even enter the basement. Homeowners here don’t need another outfit that treats a 1910 Craftsman like a 2005 spec house.
Our technicians are background-checked, uniformed, and held to The Garrison Code: arrive inside the quoted window, price in writing, complete the job by the book, leave the site clean. The 365-Day Done Right Promise covers every sealing job in writing. If the work fails within a year, we return 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 Snohomish
Air Duct Sealing in Snohomish means closing the gaps, disconnected joints, and corroded seams that let heated air escape into crawlspaces, attics, and wall cavities. In this market, we see two distinct housing stocks with two distinct sealing problems: the historic downtown and riverfront neighborhoods built between 1890 and 1920, and the hillside subdivisions from the 1970s through 1990s. A typical residential sealing job in Snohomish runs $450 – $1,200 depending on accessibility, duct material, and whether we find disconnected runs that need reconnection before sealing.
Historic Homes with Original Metal Ductwork
The unlined galvanized steel or gravity furnace ducts in pre-1920 Snohomish homes were never designed for forced-air retrofit. Joints loosen from thermal cycling. River-valley humidity corrodes seams from the inside. We inspect with cameras before sealing, because mastic over a disconnected run just traps moisture against the metal.
Hillside Flex-Duct Tracts
The corrugated plastic flex duct on Snohomish’s steeper slopes collects condensation in its ridges. Tape alone fails within a season here. We seal with mastic and mesh, or replace deteriorated flex with properly supported insulated duct where the material itself has degraded.
Duct Sealing Services in Snohomish
Duct Sealing Services in Snohomish cover more than slapping tape on a vent boot. We pressure-test the system to quantify leakage, inspect with cameras to locate hidden disconnects, then seal accessible joints with mastic and fiberglass mesh or mechanical fasteners depending on the duct material. For apartment and condo buildings with shared chases, we coordinate with building management to avoid pressurizing neighboring units. Most single-family jobs finish in one day; larger Victorians with multiple attic and crawlspace access points may need a second day. Pricing starts around $450 for straightforward flex-duct sealing and runs to $1,200 for extensive unlined metal restoration with multiple disconnected runs.
Moisture and Mold Protocol
Snohomish’s fall and winter river fog keeps indoor humidity elevated for weeks. We treat visible mold with EPA-registered sanitizer before sealing, and we won’t seal over active moisture problems without addressing the source. The fog feeds mold inside duct walls, not just at the registers.
Shared Systems and Multi-Unit Buildings
In dense downtown apartment buildings, shared return chases and dryer vent stacks complicate sealing. We map airflow paths before starting to avoid pushing odors or moisture through unsealed party-wall joints. Building management coordination is standard on these jobs.
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 Snohomish
We carry sealing and filtration products from Honeywell, Aprilaire, and Abatement Technologies, the same lines commercial HVAC crews specify. For Snohomish homeowners, that means no waiting on special orders when a job needs replacement dampers, access panels, or upgraded filtration downstream of the sealed ductwork. Our Nikro negative-air machines and Rotobrush rotary systems are on every van, so we can clean before we seal and verify after. Parts are stocked for common Snohomish configurations, including the older 6-inch and 8-inch unlined metal diameters still found in riverfront Victorians.
Common Duct Sealing Problems We See in Snohomish Homes
- Original gravity ducts leaking into wall cavities. In the 1890s – 1920s homes along the Snohomish River, unlined metal supply trunks often terminate in wall stacks that have separated from floor registers. Heated air dumps into stud bays all winter. Camera inspection finds these before we seal anything.
- Flex-duct tape failure on hillside homes. The 1970s – 1990s subdivisions above Blackman Lake and along Route 9 were built with corrugated flex duct taped at joints. The valley’s persistent moisture degrades adhesive within months. We remove failed tape and seal with mastic and mesh, or replace the flex where it has collapsed or torn.
- Shared return chases spreading odors between units. Downtown apartment buildings with original plaster and lath often have sheet-metal return chases serving multiple units. Sealing one unit’s ductwork without checking chase integrity can pressurize neighboring suites and pull cooking odors or moisture through unsealed party-wall joints.
- Rodent debris and mold in unlined metal trunks. Original unlined ducts in riverfront Victorians provide nesting paths for rodents and hold decades of organic debris. Sealing over this material traps moisture and worsens air quality. We HEPA-vacuum under negative pressure and brush-agitate before applying mastic.
Pricing for Duct Sealing in Snohomish, WA
A typical residential duct sealing job in Snohomish runs $450 – $1,200. Straightforward flex-duct sealing in a 1970s hillside ranch with good crawlspace access usually falls at the lower end. Historic downtown Victorians with original unlined metal, multiple disconnected runs, and limited access through original plaster ceilings run toward the upper end. Apartment and multi-unit jobs are priced per system after inspection.
Every job gets a written price before work starts. The price does not move at the door. We do not quote per-vent teaser rates that balloon once the technician is inside. The estimate is free, and it includes pressure testing and camera inspection so you know exactly what we’re sealing and why. Call (361) 326-5060 for an exact quote on your home.
We Also Serve Cities Near Snohomish
Our crews work throughout the north Sound, including Snohomish and neighboring Monroe, Mill Creek, Lake Stevens, and Everett. Each job follows The Garrison Standard: written price, written guarantee, background-checked uniformed technicians, and the 365-Day Done Right Promise.
Serving Snohomish, WA - Our Local Coverage Area
We’re based in the Snohomish 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 Snohomish
We start with camera inspection of the unlined metal runs, because gravity ducts in these homes often have disconnected joints hidden above original plaster ceilings. Where the metal is intact, we seal joints with mastic and fiberglass mesh rated for metal duct. Where runs have separated or corroded through, we reconnect or replace sections before sealing. Adding a single new return-air duct to a Victorian system often costs more than sealing the entire original network, so we quote both options in writing. Call (361) 326-5060 to schedule an inspection.
Yes, if the stack leaks lint into wall cavities or has disconnected joints between floors. Lint accumulation in unsealed sheet-metal stacks is a known ignition source. We inspect the full stack run with cameras, seal accessible joints with high-temperature mastic, and recommend inline lint traps where the building management agrees. We coordinate with building management to avoid disrupting neighboring units. Call (361) 326-5060 for a stack inspection quote.
The Snohomish River Valley fog keeps indoor relative humidity elevated for weeks each fall and winter. Duct leaks pull this moist air into wall cavities and attics, where it condenses on cooler surfaces and feeds mold inside duct walls, not just at the registers. Sealed ducts prevent this moisture migration. In a drier climate, leaky ducts waste energy; here, they actively damage the building and degrade air quality. Call (361) 326-5060 for a humidity and leakage assessment.
Our vans carry Nikro negative-air HEPA vacuums and Rotobrush rotary agitation systems that fit standard residential driveways and parking strips. For downtown Snohomish homes with restricted street parking, we coordinate arrival times and use compact equipment configurations that don’t block traffic. We don’t need a flatbed or crane for residential sealing. Call (361) 326-5060 to discuss access at your specific address.
Signs of leakage include rooms that never reach thermostat temperature, musty odors that return within days of cleaning, and visibly disconnected boots in the crawlspace or attic. We pressure-test the system to measure leakage in CFM, which tells us whether cleaning alone will solve the problem or whether sealing is necessary first. In Snohomish’s damp climate, we often find both: debris that needs removal and leaks that need closure. The inspection and estimate are free. Call (361) 326-5060 to book.
Written by Roy Castellanos, Owner at Hollis Air Duct Cleaning, serving Snohomish and the north Sound since 2004.