Mercer Island, King County
Chimney waterproofing on Mercer Island costs $285 to $795, depending on the chimney's height and how much exposed brick sits above the roof. We apply a vapor-permeable repellent: it keeps liquid water from soaking in while letting moisture already in the masonry escape, which a paint or a cheap sealer will not do.
Typical investment
$285–$795
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$99 plus tax, deducted when you approve the repair
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Pick what you're seeing at your Mercer Island home — we'll point you to the right fix.
What we do
The same crew, the same written quote — for Mercer Island homes.
Level 1 or Level 2 inspection, with a camera scan where warranted
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Complete sweep of the flue and firebox, protected by drop cloths and HEPA filtration
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Restoration of brick, mortar joints and firebox
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A stainless-steel or ceramic liner run the full height of the flue
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A stainless cap fitted to your flue's exact dimensions
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Cleaning of the burner, pilot and valve assembly
Learn moreRanges shown for orientation — the exact figure is written up on-site, after the inspection.
Brick is porous. Left bare through a Puget Sound winter, a chimney drinks rain on its exposed faces and holds it for weeks. On the island, that water has nowhere to go but deeper into the masonry, and the damage it does shows up as flaking brick faces, stained interior walls and mortar that crumbles long before its time.
Mercer Island is an island in the full sense: Lake Washington surrounds it, and water makes up roughly 6.5 of the city's nearly 13 square miles. King County's lake page counts it the biggest of the three major lakes in the county.
WRCC's climate summary for the state says the year's strongest blows in western Washington generally arrive from the southwest quadrant from late autumn into winter. Rain carried on that wind is driven into the brick rather than falling past it, so we pay particular attention to coverage on the weather faces.
Wet, shaded masonry is where moss does best, according to OSU Extension, and WSU's demossing manual notes its growing season covers fall, winter and spring. A treatment applied over that growth coats the moss, not the brick.
We clean by hand and brush rather than blasting with a pressure washer, which OSU warns can damage roofing around the chimney. If a tree hangs over the stack, we will mention that trimming it is the best way to keep the moss from coming back.
Every chimney waterproofing we do in Mercer Island includes:
Smoke coming back into the room, or a smell that won't go? Book the inspection first.
Book nowWaterproofing only works on masonry that is already sound. The failures we see come from repellent sprayed over open joints or a cracked crown, which traps water behind the coating. So before quoting a treatment, we check the crown, joints and flashing, and tell you if something needs repair first.
The city's emergency planners note that the island lies within the Seattle fault zone, with a minimum of two fault strands crossing it. When the 2001 Nisqually quake struck, USGS and University of Washington researchers later counted 1,556 damaged chimneys among some 60,000 surveyed in the area reaching to Mercer Island.
Cracks from shaking can be fine enough to miss from the ground. A repellent will not bridge them, and water finds them quickly. Before treating a chimney we look for step cracks and separated joints, and we recommend repair before any coating goes on.
We confirm the crown, mortar joints and flashing are tight. A coating over open cracks does more harm than good, so repairs come first if they are needed.
Moss, algae and loose dirt are brushed off by hand so the repellent reaches the brick, not whatever is growing on it.
The repellent goes on when the brick is dry enough to take it and no rain is due for the curing window, so the application is scheduled around the forecast.
You get photos, the name of the product used and a note of when a reapplication will likely be due, typically every few years.
In CSIA's view, water is a bigger threat to a masonry chimney than fire. The institute's four low-cost defenses are a cap, a correctly built crown, sound flashing and a water repellent, and the repellent works best once the other three are in place.
Western Washington gives that repellent plenty to do. The climate center describes a wet season that opens in October and peaks in winter, with morning humidity in January close to 87 percent.
What this work is quoted at for Mercer Island homes — the exact figure comes from the $99 on-site inspection, credited toward the work.
| Service | Price in Mercer Island | What that covers |
|---|---|---|
| Chimney Waterproofing | $285–$795 | Breathable sealer — reapplied every 3–5 years in this climate |
| Chimney Sweep | $189–$449 | Full flue swept, Level 1 inspection included |
| Chimney Inspection | $99 plus tax | Level 1 visual; Level 2 adds a full camera scan |
| Chimney Relining | From $1,895 | Full-length stainless liner, sized to the appliance |
| Chimney Repair | From $425 | Masonry repair — brick and mortar, scoped after diagnosis |
Ranges are what these jobs are quoted at in Mercer Island. The exact figure is set on site after a $99 inspection (credited toward the job if you go ahead), and you approve it before any work starts.
Mercer Island is an island city in the middle of Lake Washington, on Lake Washington, with mid-century and high-value waterfront homes.
Mercer IslandKing County, WA · 47.571, -122.222
Before and after
Illustrations of what each repair changes on a typical chimney — not photos of a specific job.
Before
After
Before
After
Before
After
Four steps, each one on paper — so you always know what happens next.
Choose a genuine opening on the crew's calendar. Confirmation is immediate.
Liner, crown, cap, flashing and masonry examined in order — each finding photographed.
One document, plain numbers, covering only the work your chimney genuinely needs.
The repair is completed, then handed over with before-and-after photos of every item.
$285 to $795. A short chimney with little exposed brick is near the bottom; a tall exterior stack with several faces to cover is near the top.
Film-forming coatings trap moisture inside the brick. A breathable repellent sheds rain from outside while letting vapor out, which is what brick needs to stay sound.
Usually three to five years before it needs renewing. We note the product and date so the next application can be planned rather than guessed.
A $99 on-site inspection, a written quote before any work, and photos of every item we touch.
