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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After
Before
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Before
AfterFast, Reliable Duct Sealing Across Issaquah
Duct sealing in Issaquah typically runs $800 – $2,400 for a whole-home system, with most single-family jobs falling between $1,200 and $1,800. We’re the Duct Sealing crew that serves Issaquah from our Seattle office, dispatching background-checked, uniformed technicians to neighborhoods from downtown cottages to the newer builds up in Issaquah Highlands. Call (361) 326-5060 for a free written estimate before any work starts.
We’ve worked in Issaquah long enough to know the local patterns: the flex-duct pinholes in 2005-era attics, the rodent-chewed returns backing onto Squak Mountain greenbelts, the shared dryer vent stacks in condo clusters where one clogged line affects half a building. Our pricing is written down before we touch anything. No per-vent bait-and-switch. No invoice that balloons once the van is in your driveway.
Why Hollis Air Duct Cleaning Is Issaquah’s Preferred Duct Sealing Company
Hollis Air Duct Cleaning has been part of the Garrison Partners family since 2004, and our Issaquah crews operate under The Garrison Standard: arrive inside the quoted window, price in writing, complete the job by the book, leave the site clean. Issaquah homeowners know us for showing up when we said we would, not for the lowest teaser price that jumps at the door.
Our technicians are background-checked and uniformed. You know who’s walking into your home before they arrive. Phones are answered by a live person 24 hours a day, 7 days a week. No voicemail loops, no callback queues, no waiting until Monday for a scheduling answer.
Every duct sealing job in Issaquah carries our 365-Day Done Right Promise in writing. If the seal fails within a year, we come back and make it right at no charge, including a free second visit. That’s not a verbal assurance. It’s on the paperwork.
We know Issaquah’s housing stock: the 1990s – 2010s suburban developments with flexible ductwork and tight envelopes, the older downtown cottages with original galvanized runs, the split-levels from the 1970s and 80s where moisture condensation and rodent intrusion are routine. This isn’t generic suburban knowledge. It’s specific to the Cascade foothills climate and the way this city was built.
Duct Sealing Services in Issaquah
Duct Sealing Services in Issaquah address the leaks, gaps, and disconnected joints that let conditioned air escape and unconditioned air infiltrate. In this market, the job is rarely just about energy efficiency. Issaquah’s location in the Cascade foothills means long, damp winters and heavy tree pollen seasons force residents to rely on closed windows and HVAC systems for months, but the resulting duct problems are compounded by aggressive moss and mold spores that infiltrate outdoor air intakes. When your ducts leak, they don’t just waste heated or cooled air. They pull in crawlspace moisture, attic dust, and rodent debris from greenbelt-adjacent walls.
A typical whole-home duct sealing in Issaquah runs $800 – $2,400 depending on system size, accessibility, and whether we find rodent damage or mold that requires remediation first. We use mastic sealant and UL-181 tape on all accessible joints, then pressure-test the system to verify results. The price is written before we start. It does not move.
Leak Detection and Pressure Testing
We pressurize your duct system and measure airflow loss at the registers. In Issaquah’s tightly sealed newer homes, even a 15% leak rate forces the HVAC system to work significantly harder. Our technicians document the before-and-after with digital manometers so you see the improvement in hard numbers, not promises.
Mastic Sealing and Joint Repair
We seal plenum connections, takeoff collars, and flex-duct joints with brush-applied mastic that remains flexible through freeze-thaw cycles. Tape alone fails in Issaquah’s humid crawlspaces. Mastic doesn’t. For rodent-damaged sections near greenbelt walls, we remove the contaminated material, sanitize the run, and install new duct with proper mechanical fastening before sealing.
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 Issaquah
Duct Insulation in Issaquah protects against the condensation that forms when warm, humid air hits cold duct surfaces in crawlspaces and attics. With over 150 rainy days per year and persistent high humidity, Issaquah’s climate creates ideal conditions for mold and mildew growth inside ductwork. Uninsulated or poorly insulated ducts sweat. That moisture drips onto ceiling drywall, breeds mold spores, and degrades the duct sealant we just applied.
Duct insulation in Issaquah typically adds $400 – $1,200 to a sealing job, depending on linear footage and whether we’re working in a tight attic or accessible crawlspace. We use Guardsman insulation products rated for Pacific Northwest moisture exposure, installed with vapor-barrier facing correctly oriented to the conditioned side. The price is agreed in writing before work begins.
Condensation Control in Crawlspaces
Issaquah’s 1970s – 80s split-levels and older cottages often have ducts routed through vented crawlspaces where ground moisture meets cold supply air. We wrap the sealed ducts with insulation that maintains its R-value at high humidity, then secure it with proper fasteners that won’t sag or create gaps where condensation can restart.
Attic Insulation for Tight Newer Homes
In Issaquah Highlands and similar 1990s – 2010s developments, attics are often cramped and ducts run near the roof deck. We use compact, high-R insulation that fits in tight bays without compressing, maintaining thermal performance where space is limited and access is awkward.
Trusted Brands We Service in Issaquah
Our Issaquah crews carry professional-grade equipment from Nikro negative-air machines, Honeywell filtration components, and Aprilaire humidity control products. We stock Guardsman insulation and sealing materials locally so we’re not waiting on freight when your job is scheduled. For duct sealing specifically, we source mastic compounds and UL-181 tapes rated for the Pacific Northwest’s wet climate, not the hardware-store variety that peels in crawlspace humidity. When we need replacement flex duct or fittings for Issaquah’s common 6-inch and 8-inch residential systems, we have them on the van or can get them next-day from our Seattle-area inventory.
Common Duct Sealing Problems We See in Issaquah Homes
- Flex duct pinholes in Issaquah Highlands attics. The original flex duct in 2000s-era homes develops condensation pinholes where the vapor barrier degrades in hot-cold attic cycling. Sealing the leaks without replacing the damaged section is a temporary fix at best. We camera-inspect first, then seal or replace based on what we find.
- Rodent-chewed returns near Squak Mountain greenbelts. Homes backing onto wooded areas frequently have duct runs penetrated by mice or rats seeking warmth and nesting material. Sealing over the damage traps droppings and urine in the airflow path. We remove the contaminated duct, sanitize the cavity, and install new material with rodent-resistant screening where appropriate.
- Disconnected takeoff collars in tight 1990s attics. installers in that era often had minimal working space and sometimes failed to secure flex duct to metal collars with proper mechanical fasteners. The joint loosens over years of thermal cycling. We reattach with screws or draw bands, then seal with mastic.
- Shared dryer vent stack restrictions in condo clusters. Issaquah’s denser apartment and condo buildings often have lint buildup in shared vertical runs that restricts airflow and creates fire risk. Sealing the duct without clearing the lint pathway and verifying the full run through camera inspection leaves a serious hazard and fails the point of the service.
Pricing for Duct Sealing in Issaquah, WA
A typical duct sealing job in Issaquah runs $800 – $2,400 for a whole-home system. Most single-family homes in the $1,200 – $1,800 range. Duct insulation adds $400 – $1,200. What moves the needle: system size (more ducts, more labor), accessibility (tight attics take longer), and whether we find rodent damage, mold, or disconnected sections that need repair before sealing.
We do not quote per-vent prices. That structure invites bait-and-switch. We price per system, agreed in writing before work starts, based on what we find during inspection. The inspection itself is free. No charge to look, measure, and give you a written number you can compare.
If you’re in a condo or apartment with shared systems, call (361) 326-5060. We’ll coordinate with building management and work within your HOA scheduling requirements. The estimate is still free, and the price is still fixed before we begin.
We Also Serve Cities Near Issaquah
Our Duct Sealing in Issaquah crews also work in Hobart, Maple Valley, Sammamish, and Snoqualmie. Scheduling is coordinated from our Seattle office, with local technicians dispatched to each area. Same written pricing, same 365-Day Done Right Promise, same background-checked uniformed crews.
Serving Issaquah, WA - Our Local Coverage Area
We’re based in the Issaquah 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 Issaquah
Yes. We’ve worked in Issaquah Highlands buildings with underground parking, loading-zone restrictions, and narrow stairwells. We coordinate with your building management for access, use compact equipment that fits through standard doorways, and schedule within HOA maintenance windows when required. Call (361) 326-5060 and we’ll walk through the logistics before we quote.
Issaquah’s damp climate means leaky ducts pull in crawlspace moisture and mold spores year-round, not just during heating or cooling seasons. In a drier climate, a 20% duct leak mostly wastes energy. Here, it feeds biological growth inside your ducts and circulates musty air through your home. Sealing stops both the energy loss and the moisture intrusion.
We remove the damaged duct section entirely, HEPA-vacuum the cavity, and apply sanitizing treatment before installing new material. Sealing over rodent debris traps contaminants in your airflow. We use camera inspection to verify the full run is clean, then seal with mastic and install rodent-resistant screening at exterior entry points where appropriate.
No. Sealing a dryer vent without clearing existing lint restricts airflow and increases fire risk. We camera-inspect the full vertical run, remove lint accumulation with rotary brushing and negative-air extraction, then seal any disconnected joints or gaps. The lint removal is the critical step; sealing comes after.
We follow NADCA ACR standards for assessment, cleaning, and restoration of HVAC systems, including post-sealing verification testing. For Issaquah’s tightly built homes, we pay particular attention to pressure balancing after sealing, since reducing duct leakage changes the home’s air exchange rate and can affect combustion appliance drafting if not verified.
Written by Roy Castellanos, Owner at Hollis Air Duct Cleaning, serving Issaquah since 2004 as part of the Garrison Partners family.