A brown ring on the ceiling next to the chimney says water got in. It does not say where. Flashing, the metal that seals the gap between the stack and the roof, is the most common suspect, but a cracked crown, porous brick, an open flue or a failing roof nearby can leave exactly the same stain. Fixing the wrong one means paying for a repair and still putting a bucket out in November. The good news is that leaks leave clues: where the water shows up, what kind of weather brings it, and how long after the rain starts. This guide walks through reading those clues around a Tacoma house, and what a proper flashing repair involves when the metal is to blame.
Reading the clues
Start inside, with a flashlight, during or just after a rain. The attic is more useful than the ceiling below it, because it shows where the water first touches wood.
| What you notice | Most likely source | How to confirm |
|---|---|---|
| Wet rafters or sheathing where the roof meets the chimney | Flashing lifted, rusted or missing counter-flashing | Look at the metal from the roof; check for gaps at the brick |
| Damp only on the uphill side of the stack | Water and debris pooling behind the chimney | Check for a missing or undersized cricket |
| Water inside the firebox or on the damper | Open flue or cracked crown | Look for a cap and inspect the crown surface |
| Brick face dark and wet inside the attic | Water soaking through the masonry itself | Spray test on the exterior brick |
| Stain appears only in wind-driven storms | A gap on the windward face | Compare stain timing with wind direction |
Why wind matters here
WeatherSpark reports that Tacoma's wind blows mainly from the south from about September through June, turning to the northwest only in mid-summer. The windier season runs from mid-October to late April, which lines up closely with the rainy one. Through the rainy months, then, a southerly wind is the usual companion of a storm.
That tends to put the south face of a chimney, and the flashing along it, in the path of the hardest wind-driven rain. A leak that shows up only in certain storms and stays dry in steady drizzle often traces back to that side.
Moss, debris and the uphill side
The back of a chimney, the side facing up the roof, catches everything that slides down: needles, leaves, moss. Moss, in Oregon State University Extension's account, acts like a sponge full of grit: it keeps the roof surface damp and, given time, pries shingles up so water gets underneath. Against a chimney, that damp mat sits right on top of the flashing joint.
Washington's residential code addresses the problem for larger stacks by requiring a cricket, a small peaked diverter, on the uphill side of any stack more than 30 inches across that stops short of the ridge. If your chimney is that wide and the roof behind it is flat, water has nowhere to go but sideways into the joint. When treating moss, keep in mind OSU's warning that zinc sulfate corrodes copper, since some older chimneys carry copper flashing.
What a proper repair includes
Good chimney flashing is two layers. Step flashing is woven in with the shingles along the sides, and counter-flashing is set into a cut in the mortar joint and folded down over it, so water running down the brick lands on metal instead of the gap. A repair that only smears sealant along the top edge skips the second layer.
Depending on what the inspection finds, the work may be a reseal of sound metal, replacement of rusted pieces, or new step and counter-flashing all around, plus a cricket if one is missing. It is also the moment to check the crown and cap, because a flashing job on a chimney that leaks from the top will not stop the stain.
Ask to see photos of the old metal once it is off. Rust holes, nails driven through the exposed face, or counter-flashing that was only glued to the brick explain why the leak happened, and they give you a reference point if a stain ever returns.
What flashing work runs
Our chimney flashing repair is priced from $330 to $1,500; resealing sound metal sits at the low end and full replacement with counter-flashing at the top. Homeyou's Tacoma estimate for resealing cracks and replacing flashings is $300 to $400, and Fixr's national average for flashing repair is $200 to $300. Those published figures belong to other companies and rarely include a cricket or crown work. For $99 plus tax we inspect the chimney in person, and that fee is applied to the flashing job once you accept the written quote.
Frequently asked questions
Can I seal leaking flashing with roofing caulk?
As a stopgap, sometimes. Caulk bridges a gap for a season or two, but if the metal has lifted, rusted through or was never counter-flashed into the brick, the leak returns once the sealant ages.
Why does my chimney only leak in some storms?
Wind direction is the usual answer. Rain driven hard against one face can find a gap that ordinary vertical rain never reaches, so note which way the wind blew the day the stain grew.
Does a wide chimney need anything special?
Yes, if it is broad and sits below the ridge line: the state code calls for a cricket there once the width passes 30 inches. Without one, water and debris pool against the uphill side.
How soon should a flashing leak be fixed?
Before the next wet season if you can. Water that reaches the framing stays there through the months of rain, and soaked wood and insulation cost far more to replace than metal.
Sources
- WeatherSpark — Tacoma climate — accessed September 24, 2026
- OSU Extension — Controlling roof moss — accessed September 24, 2026
- UpCodes — WA Residential Code 2021, Chapter 10 — accessed September 24, 2026
- Homeyou — Chimney Repair in Tacoma — accessed September 24, 2026
- Fixr — Chimney Repair Cost — accessed September 24, 2026
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