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 Sammamish
Most Duct Sealing jobs in Sammamish run $450 – $1,200 for a whole-home seal on typical 2,500 – 4,000 square foot plateau homes, and we can usually schedule within a few business days. Our crews dispatch from the Seattle office and know the Sammamish Plateau well, from the winding streets of Klahanie to the wooded lots in Trossachs and the older rigid trunk lines in Sahalee. If you’re smelling musty air from your registers or your upstairs rooms never reach temperature, the problem is often leaky ductwork in your vented attic, and sealing it properly takes local knowledge of what this wet climate does to flex duct. Call (361) 326-5060 for a free estimate.
Why Hollis Air Duct Cleaning Is Sammamish’s Preferred Duct Sealing Company
We’ve been sealing ducts in Sammamish since long before the current building boom, and our reputation here rests on one thing: we treat plateau attics differently than drier neighborhoods west of Lake Sammamish. Sammamish homeowners leave reviews mentioning our written prices and the fact that our techs arrive uniformed and background-checked, which matters when you’re letting someone into your crawlspace or attic for two hours.
Response time to Sammamish is typically same-week, with scheduling coordinated from our Seattle office and crews routing daily through the plateau. We know which Klahanie phases have the original 1980s rigid sheet-metal trunks that need camera inspection first, and which Trossachs builds have the flex-duct runs that squirrels love to nest in. That local specificity saves you from paying for a seal that fails six months later because the underlying problem, damp or rodent damage, was never addressed.
Duct Sealing Services in Sammamish
Duct Sealing Services in Sammamish focus on closing leaks in your forced-air distribution system, but the real work here is understanding whether your attic ducts are dry enough to seal in the first place. Our typical Sammamish job involves sealing 20 – 40 year old flex-duct runs in unconditioned attics that have been damp for months, which means we inspect with a camera, confirm moisture levels, and dry or replace wet sections before applying mastic and foil tape to joints and tears. A full-home seal on a 3,000 square foot plateau house generally falls between $650 and $1,100, with larger homes or those needing partial replacement running toward the higher end.
Attic Moisture Assessment Before Sealing
We run a humidity probe and visual camera inspection on every Sammamish attic job before touching tape or mastic. Sealing damp flex duct traps moisture inside the insulation jacket, and in this marine climate that means mold returns within a season. If your runs are wet, we flag it and dry or replace them first.
Mastic and Foil Tape Application
For dry, intact ductwork, we seal joints and tears with duct mastic, a thick water-based sealant that remains flexible, reinforced with foil tape at stress points. This outlasts tape-only repairs by years, especially important in Sammamish where temperature swings between cool wet winters and the occasional summer heat wave stress materials.
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.
Duct Insulation in Sammamish
Duct Insulation in Sammamish addresses the heat loss and condensation that plague unconditioned plateau attics. Original builder-grade insulation on flex-duct runs in homes from Klahanie to Beaver Lake is often compressed, moisture-damaged, or missing entirely at joints, meaning your heated air loses 20 – 30 degrees before reaching the master bedroom. We install new R-6 or R-8 foil-faced insulation over sealed runs, with typical whole-home jobs running $800 – $1,500 depending on linear footage and accessibility. The payoff is immediate: rooms that previously never reached thermostat temperature now do, and your furnace cycles less.
Condensation Control in Wet Attics
Sammamish’s marine air keeps attic surfaces cold and damp eight months a year. Proper insulation with a sealed vapor barrier prevents warm supply air from hitting cold duct walls and condensing, which is what creates the musty smell so many plateau homeowners report.
Insulation Replacement After Rodent Damage
Douglas squirrels and field mice shred flex-duct insulation for nesting material, especially in Trossachs and Sahalee where firs overhang the roofline. We remove contaminated insulation, seal the underlying duct, and install new, properly secured insulation that resists future intrusion.
Trusted Brands We Service in Sammamish
Our crews carry professional-grade equipment from Rotobrush, Nikro, and Abatement Technologies on every Sammamish truck, and we stock filtration products from Honeywell and Aprilaire for same-day installation. That matters on the plateau, where a sealing job often pairs with an air-handler upgrade or filter upsize to handle the pollen and wildfire smoke that increasingly define this market. We don’t run to a supplier in Bellevue mid-job; the parts are on the van, and the work finishes in one visit.
Common Duct Sealing Problems We See in Sammamish Homes
- Wet flex-duct in vented attics. Sammamish’s 400 – 500 foot elevation and marine air mean original builder-grade flex duct in unconditioned attics runs damp six to eight months annually. Sealing over that moisture without drying it first traps mold inside the insulation jacket, and the musty smell returns within weeks.
- Rodent-chewed runs under fir overhangs. Douglas squirrels and field mice nest in attic ductwork throughout Trossachs and Sahalee, shredding flex-duct liners and packing fir needles into return trunks. Sealing over the damage with tape hides the problem but doesn’t restore airflow or filtration.
- Debris accumulation in rigid sheet-metal joints. Older Klahanie and Sahalee pockets built in the late 1970s and 1980s used rigid trunk lines with screwed joints that collect decades of dust and pollen. Resealing without source removal boxes in the grime and restricts airflow.
- Undersized filters allowing bypass. Many original Sammamish systems use 1-inch filter slots rated for MERV 8 maximum, but plateau homeowners increasingly want MERV 13 for wildfire smoke season. We check static pressure before and after any seal to ensure your blower motor isn’t overworking.
Pricing for Duct Sealing in Sammamish, WA
A typical duct sealing job in Sammamish runs $450 – $650 for partial sealing of accessible leaks in a smaller home, $650 – $1,100 for whole-home sealing on a standard 2,500 – 3,500 square foot plateau house, and $1,100 – $1,500 for larger homes or those needing significant flex-duct replacement before sealing. Duct insulation adds $800 – $1,500 depending on linear footage. What moves the price: attic accessibility (tight trusses versus walkable space), extent of moisture or rodent damage requiring repair before sealing, and whether we’re also upsizing filtration or addressing static pressure issues. We write the price down before any work starts, and it does not move at the door. Call (361) 326-5060 for a free estimate.
We Also Serve Cities Near Sammamish
Our Duct Sealing in Sammamish crews route daily through Redmond, Bellevue, Kirkland, and Duvall, but the plateau’s wet attics and fir-overhung roofs make Sammamish a distinct market with distinct failure modes. We bring the same written pricing and 365-Day Done Right Promise to every job, whether it’s a 1990s flex-duct system in Klahanie or a rigid trunk line in Sahalee.
Serving Sammamish, WA - Our Local Coverage Area
We’re based in the Sammamish 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 Sammamish
Duct sealing helps with musty smells only if the root cause is leaky, damp ductwork drawing attic air into your living space. In Sammamish’s wet plateau climate, that is often exactly the problem: moist marine air enters torn flex-duct runs, mold grows on the insulation jacket, and your blower distributes the smell. Sealing dry, clean ducts with mastic stops that infiltration. A fogging “sanitiser” sprayed into dirty ducts without sealing the leaks is a temporary cover-up that does nothing to stop new moisture from entering. Call (361) 326-5060 and we’ll camera-inspect to tell you which problem you actually have.
Seal it if the metal is intact and the joints are accessible; replace sections if the trunk is corroded or the joints are packed with decades of debris that can’t be source-removed. In Sahalee’s older pockets, we often find rigid trunks with screwed joints that have never been opened, collecting fir pollen and dust since installation. We run a camera first. If the interior is reasonably clean, we disassemble, clean, reseal with mastic, and reinstall. If the metal is failing or the debris is baked on, we quote replacement by section. Call (361) 326-5060 for an inspection.
Sealing alone does not solve rodent intrusion; it must be paired with exclusion work and often replacement of chewed flex-duct sections. In Trossachs, where Douglas fir branches touch or overhang roofs, squirrels and mice treat attic vents and damaged soffits as entry points. We seal the ductwork with mastic and foil tape after removing contaminated insulation and damaged liner, but we also flag the entry points we find and recommend a pest professional for exclusion. Sealing over chewed flex-duct without addressing the rodent access guarantees repeat failure. Call (361) 326-5060 for a full assessment.
Yes, if your system can handle the static pressure; no, if it can’t and you haven’t sealed your ducts first. MERV 13 captures fine particulate from Cascade wildfire smoke, but it also restricts airflow more than standard filters. In Sammamish homes with leaky ductwork, the blower already works harder than designed; adding MERV 13 without sealing leaks first can overheat the motor or freeze the coil. We measure static pressure before and after sealing to determine whether your system can support MERV 13, or whether MERV 11 with sealed ducts is the better match. Call (361) 326-5060 for testing.
Ask for a pre-seal moisture reading and a post-seal pressure test, both of which we provide in writing on every Sammamish job. NADCA standards require inspection before sealing, source removal of contamination, and verification of seal integrity with a duct blaster or pressure pan test. In Sammamish’s wet climate, the critical deviation from standard is skipping the moisture check: any tech who applies mastic or tape without confirming the flex-duct is dry is not following best practice, regardless of what standards they claim. We document humidity levels, photo the camera inspection, and give you the written report. Call (361) 326-5060 if you want to verify a previous company’s work.
Written by Roy Castellanos, Owner at Hollis Air Duct Cleaning, serving Sammamish since 2004.