A water stain on the ceiling next to your chimney means water is getting in at the top of the chimney or where it meets the roof, running down the outside of the chimney structure, and landing on the drywall. The six causes we find most often in Seattle-area homes, in rough order of how common they are, are: failed flashing, a cracked crown, a rusted chase cover on a framed chimney, saturated brick and mortar, a missing or damaged cap sending water down the flue, and condensation inside the flue. A roof leak that has nothing to do with the chimney is the seventh possibility, and we rule it out rather than assume it.
Because a stain on the ceiling is water that has already traveled through the attic and the framing, it is a late symptom. By the time the drywall shows a brown ring, the roof deck, chimney framing, or insulation above it has been wet for a while. That is why we treat a chimney-adjacent ceiling stain as something to diagnose now, not after the wet season. At Sea-Tac, the NOAA 1991-2020 normals put November at 6.31 inches of rain and the November-through-January stretch at about 17.8 inches, roughly 44 percent of the year's total. A leak found in October has the whole winter ahead of it.
How to read the stain before you call
A few details tell us a lot, and none of them require going up a ladder. Please stay off the roof.
- Position. A stain on the uphill (toward the ridge) side of the chimney points to flashing or a missing cricket. A stain on the downhill side can be flashing or a crown or cap leak running down the face. A stain centered on the chimney, or in the firebox, points to the top of the stack.
- Timing. Does it darken during rain, a few hours after, or only after several wet days in a row? Fast means an open path. Slow means seepage through masonry or a small flashing gap.
- Color and edge. A crisp brown ring that grows is active water. Rust-colored streaks suggest corroded metal (flashing or chase cover). A white powdery bloom on exposed brick is efflorescence, which means the masonry itself is saturated.
- Chimney type. Brick masonry, or a siding-wrapped framed chase with a flat metal top? The likely causes are different.
The 6 causes
1. Failed flashing
Flashing is the layered metal that seals the joint between the chimney and the roof. When the sealant dries out, the counter flashing pulls loose from its mortar joint, the metal rusts, or a re-roof left the step flashing caulked to the brick with no counter flashing at all, water runs behind it and down into the attic. This is the single most common cause of a ceiling stain beside a chimney, and it often shows up on one side of the chimney only. The fix is a flashing repair if the metal is sound and only the seal has failed, or a full replacement if the metal is rusted, lifted, or was installed wrong.
2. Cracked crown
On a masonry chimney, the crown is the sloped slab on top that sheds water away from the brick. Crown cracks are a Puget Sound specialty because of the winter pattern: Sea-Tac's normal lows in December through February hover around 37 F, so the region sees roughly 60 days a year that touch freezing but only about 4 that stay below freezing all day. Water in a crack freezes overnight and thaws by midday, again and again, and the Brick Industry Association notes that repeated freeze-thaw of saturated masonry causes cracking and spalling. Water that gets through the crown runs down between the flue liner and the brick and can emerge anywhere below, including the ceiling. Minor cracks in a solid crown can be sealed; a crown that is broken through needs a crown rebuild, which starts at $299.
3. Rusted chase cover
If your chimney is wrapped in siding rather than brick, it is a framed chase around a factory-built fireplace, and the top is a flat metal chase cover. These are common in homes built around the region since the mid-1980s, which describes a large share of Renton, Kent, Federal Way, Redmond, Bothell, and Gig Harbor housing. Galvanized covers rust where water ponds and around the flue collar. Once they rust through, water drops straight into the chase, soaks the framing and the insulation around the flue pipe, and shows up as a ceiling stain or a drip at the fireplace. Rust streaks on the siding below the top of the chase are the giveaway. A chase cover replacement starts at $299. If the framing under it has rotted, the chase needs repair or a rebuild, which starts at $299.
4. Saturated brick and mortar
Brick and mortar absorb water and release it when they dry. In a wet season where the region gets roughly 150 to 156 days of measurable precipitation a year, an older chimney may not get a chance to dry out between storms. BIA Technical Note 7B describes what follows: eroded or improperly filled joints let water through, and masonry that takes on disproportionate water shows efflorescence, cracking, and spalling. Moss on the shaded side of a chimney holds water against the brick and spreads fastest October through April. This kind of leak is slow and diffuse. The stain grows over days, the plaster feels damp rather than dripping, and paint may peel. Repointing open joints and replacing spalled brick is a chimney repair job, and a breathable sealer only makes sense after the masonry is sound.
5. Missing or damaged cap
An uncapped flue takes rain straight down to the smoke shelf and damper. Most of that water shows up in the firebox, but a flue with a cracked liner or an open joint can also shed it into the space between the liner and the brick, and from there into the attic framing. A chimney cap replacement is usually the least expensive item on this list, and it also keeps birds, raccoons, and leaves out of the flue.
6. Condensation inside the flue
Not every stain is rain. A gas or high-efficiency appliance venting into an oversized or unlined masonry flue produces exhaust that cools and condenses on the flue walls. That moisture soaks into the brick and can work its way to the ceiling just like a rain leak. The tell is that the stain tracks the appliance running rather than the weather, and it may be worst on cold, dry mornings. We check for this during the inspection because the fix is a liner issue, not a flashing or crown issue.
The seventh possibility: it is the roof, not the chimney
A chimney is often the nearest thing to a roof leak, so it gets the blame. A cracked pipe boot, a nail pop, or a damaged shingle uphill of the chimney can let water track along a rafter and drop next to the chimney. We look at the roof surface around the chimney during the inspection. If the chimney is not the cause, we tell you so you can call a roofer, rather than selling you chimney work that would not have stopped the stain.
Why we inspect before we quote
Each of these causes has a different fix and a different price, and two of them can be present at the same time. Sealing the flashing on a chimney with a broken crown stops half the leak. A chimney inspection looks at the crown, cap or chase cover, flashing, masonry, and the inside of the flue, with a camera where needed, and gives you a written answer about what is letting water in. The quote is free. If you already have a quote from another company, we give a free second-opinion quote, price match, and take 10 to 25 percent off.
Our guarantee is plain: if you're not happy, we're not done. We come back and make it right at no charge.
What to do next
- Photograph the stain today and again after the next rain so you can see whether it is growing.
- Check the attic, if you can do so safely from inside, for wet insulation or dark framing around the chimney. Do not go on the roof.
- Do not light a fire if the firebox or damper is wet.
- Call 206-453-2045 or request a free quote online. Same-day service is often available across Seattle, Tacoma, Everett, and the surrounding Puget Sound area.
Questions homeowners ask
Is a water stain near the chimney always a chimney leak?
No. It is the most likely cause, but a roof leak uphill of the chimney can track along a rafter and drop in the same spot. We check the roof surface around the chimney during the inspection and tell you if a roofer is the right call instead.
Should I paint over the stain once it dries?
Not until the leak is fixed and the framing above it has dried out. Painting over an active leak hides the evidence you need and can trap moisture in the drywall. Once the repair is done and the area has dried, a stain-blocking primer and paint will cover it.
Can a ceiling stain near the chimney cause mold?
Any drywall or framing that stays wet can support mold growth, and a slow chimney leak keeps the area damp for months in a Seattle winter. That is one reason to diagnose the leak now rather than wait for summer.
Why is the stain on only one side of the chimney?
Flashing fails on one side before the other, and crown cracks and cap gaps often direct water down one face. A stain on the uphill side often points to flashing or a missing cricket; a stain on one lower corner often points to the crown or cap. We use the position as a starting clue and confirm it on the chimney.
Does homeowners insurance cover a chimney leak?
Policies differ, and we are not able to tell you what yours covers. What we can do is give you a written inspection report and quote that documents the cause and the repair, which is what an insurer usually asks for.
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