A blocked chimney shows itself in five ways: smoke coming back into the room, a smell from the fireplace when there is no fire, debris falling into the firebox, a fire that will not draw or keeps going out, and noises in the flue. If you notice any one of them, stop using the fireplace and call us at 206-453-2045 for a chimney cleaning. We find the blockage with a camera, clear it, and tell you what caused it, with a free quote first and same-day service often available across Seattle, Tacoma, Everett and the Puget Sound area.
Blockages are not the same as the creosote buildup a routine sweep handles. A sweep is maintenance for a working wood-burning flue. A blockage is something physically in the way: a nest, a dead animal, a collapsed flue tile, a chunk of crown, a rusted damper, a wad of leaves, or a plug of wet soot. It needs to be identified and removed, and the flue needs to be checked for damage afterward. Here are the five signs, in the order homeowners usually notice them.
1. Smoke comes back into the room
This is the clearest sign and the one that gets people to call. When you light a fire and smoke rolls out over the top of the firebox instead of going up, the flue is not moving enough air. Sometimes that is a cold-flue problem that clears after a minute of warming. If it does not clear, or it gets worse as the fire grows, something is restricting the flue. A partial blockage from a nest or collapsed tile will let a little air through and then choke once the fire is producing real volume.
Smoke back-up is not just a nuisance. Wood smoke carries carbon monoxide, and a fireplace that smokes into the house is one that is also putting CO into the house. If smoke is coming in, put the fire out the safe way (let it burn down, do not douse a hot firebox with water), open a window, and do not use the fireplace again until it has been looked at.
2. A smell from the fireplace when there is no fire
A healthy flue smells faintly of smoke on a humid day and that is about it. A blocked flue smells of whatever is blocking it. A dead animal produces a rotten smell that peaks on warm days and draws flies. A bird nest smells musty and sharp from droppings. A plug of wet creosote and soot smells like an old campfire that someone poured water on, and in Seattle that one is common: the Sea-Tac normals put annual rainfall at 40.34 inches, and November alone averages 6.31 inches. An uncapped flue takes that water straight down onto the smoke shelf, where it mixes with soot into a heavy paste that swells and blocks the throat of the flue. Many people notice the smell first in late fall when the rain starts and the house is closed up.
Some fireplace odors are a draft problem rather than a blockage, where air is being pulled down the flue into a house that is under negative pressure. We can tell the difference on site, but a strong, new or rotten smell means assume blockage until proven otherwise.
3. Debris in the firebox
Look at the floor of the firebox and the area just inside the damper. Twigs, grass, feathers, leaves, fur or string mean a nest above. Pieces of orange-brown clay with a smooth face mean flue tiles are cracking and falling; that is a structural problem, not just a blockage, and it needs a camera inspection before the fireplace is used again. Gray or white chunks of cement mean the crown is breaking up and dropping into the flue, which also tells you water has been getting into the masonry. Loose, shiny black flakes are creosote shedding off the flue walls; a lot of it at once usually means the flue has had a small fire or is badly overdue for a sweep.
Debris in the firebox is the sign people ignore longest because it does not seem urgent. It is the one we wish people called about sooner, because what is in the firebox is only what made it past the damper. There is usually much more sitting on the smoke shelf.
4. A fire that will not draw or keeps going out
A fire needs a column of hot air rising through the flue to pull fresh air in at the bottom. If the flue is restricted, the fire starves. The symptoms are a fire that is hard to start even with dry wood, that burns lazily with a lot of smoke and not much flame, that goes out when you close the doors, or that only burns well with a window open. The same goes for wood stoves and inserts: if the stove used to run with the air control mostly shut and now needs it wide open, check the flue before blaming the wood.
This sign often shows up gradually over a season as a partial blockage builds. By the time the fire is really struggling the restriction is significant, and burning a smoldering, oxygen-starved fire is exactly how creosote builds fastest, which makes the blockage worse.
5. Noises in the flue
Scratching, fluttering, chirping or thumping means a live animal, and the blockage is likely a nest or the animal itself. Do not light a fire to drive it out; that kills the animal and can ignite the nest, and if the bird is a chimney swift it is protected by the federal Migratory Bird Treaty Act. Read There's an Animal in My Chimney — What Do I Do? for the step-by-step, and call us for animal and nest removal.
Not every noise is an animal. A rattling or clanging on windy days can be a loose or rusted damper, a cap that has come unfastened, or a chase cover lifting. A damper that has rusted and seized partly closed is itself a blockage, and it is common in older Seattle and Tacoma masonry fireplaces that have not been used in years.
What blocks chimneys around Seattle
- Bird and animal nests. The most common blockage we clear, almost always in an uncapped masonry flue.
- Dead animals. Squirrels and birds that fell in and could not climb out.
- Leaves and needles. Seattle-area chimneys sit under a lot of fir, cedar and maple. An open flue fills over a few fall seasons.
- Wet soot and creosote. Rain down an uncapped flue makes a paste that hardens on the smoke shelf and at the throat.
- Collapsed flue tiles and crown debris. Water gets into the masonry, freezes and thaws, and pieces let go. Winter lows at Sea-Tac average just above freezing, so wet masonry here crosses the freezing line over and over rather than staying frozen, and that cycling is what breaks tile and concrete apart.
- Rusted or seized dampers. Especially in fireplaces that have sat unused.
- Moss. Moss grows fastest here from October through April on shaded surfaces, and a mossy chimney top can shed clumps down the flue and hold water against the crown.
How we clear a blocked chimney
First we look. A camera down the flue shows what the blockage is, where it is, and whether the flue behind it is damaged. Then we clear it from the top and the bottom with the firebox sealed off from the room, so nest material, soot and debris go into our containment and not onto your floor. Animals come out alive where possible. Once the flue is clear we run the camera again to confirm it is open end to end and to check for cracked tiles, gaps in the mortar joints, and damage to the smoke chamber. If the blockage came from a failed crown or cap, we tell you and give a free quote for the repair. A chimney cap with a mesh screen prevents most blockages outright, and a crown rebuild starting at $299 stops the top of the chimney from crumbling into the flue.
If the only thing wrong is creosote on the flue walls and there is no physical obstruction, that is a sweep rather than a cleaning, and our sweep and inspection special starts at $299. We will tell you honestly which one you need.
What to do next
If you have noticed any of the five signs, stop using the fireplace, keep the damper closed, and call 206-453-2045. Do not go on the roof to look, and do not try to push anything down or pull anything up the flue yourself; a blockage that shifts can wedge tighter or drop onto a damper. We serve Seattle, Tacoma, Everett, the Eastside and the road-accessible Puget Sound from our Renton office. The quote is free, we give a free second-opinion quote if you already have one, and we match competitor pricing with a 10 to 25 percent discount. If you are not happy with the work, we are not done; we come back and make it right at no charge. NFPA 211 recommends an annual chimney inspection, and a blocked flue is the single best argument for why.
Questions homeowners ask
Is it safe to use the fireplace if only a little smoke comes in?
No. Any smoke entering the room means the flue is not drafting properly, and carbon monoxide enters with it. Stop using the fireplace until the flue has been inspected and cleared.
What is the difference between a chimney cleaning and a sweep?
A sweep removes creosote and soot from a working wood-burning flue as routine maintenance. A cleaning clears a physical blockage such as a nest, debris, a dead animal, or a plug of wet soot, and deals with the odor and damage that come with it.
Why does my fireplace smell when I'm not using it?
Usually something is in the flue: a dead animal, a nest, or wet creosote and soot on the smoke shelf from rain coming down an uncapped chimney. Seattle's wet fall months make the wet-soot smell especially common. A camera inspection finds the cause.
Can I clear the blockage myself?
We do not recommend it. Pushing on a blockage can wedge it tighter or drop it onto the damper, roof access in Seattle is slippery most of the year, and some blockages hide cracked flue tiles that need to be found, not just cleared.
How do I stop my chimney from getting blocked again?
A properly sized chimney cap with a mesh screen stops nests, animals, leaves and most rain. Keeping the crown sound stops debris from above. An annual inspection, which NFPA 211 recommends, catches the rest early.
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