Smoke and draft problems
- Smoke rolls into the room instead of up the flue. Usually a draft problem: a blocked flue, heavy creosote, a cold or undersized flue, or a missing cap letting downdrafts in. A sweep and inspection find the cause; an insulated liner often fixes chronic poor draft.
- Fires are hard to start or keep going. Weak draft, a damp flue, or a partial blockage. Start with a sweep.
- A downdraft blows cold air or ash into the room. Often a missing or damaged cap, or a damper that no longer seals.
Smells coming from the fireplace
- A strong smoky or barbecue smell, worse in summer or humidity. Creosote in the flue absorbing moisture. Sweeping removes the source.
- A musty, damp smell. Water is getting in — typically a failing cap, crown or flashing.
- An animal or rotting smell. A bird, squirrel or raccoon, or an old nest, in the flue. A cap keeps them out once the flue is cleared.
Water, stains and white deposits
- Water in the firebox, or dripping sounds inside the chimney. A failed cap, a cracked crown, or bad flashing where the chimney meets the roof.
- White, crusty staining on the brick (efflorescence). Water is moving through the masonry — a moisture problem even when you see no drips.
- Rust on the damper or firebox, or a damper that sticks. Moisture is reaching metal parts it should never touch.
- Stains on the ceiling or wall around the chimney. A leak that has already reached the interior; it will not fix itself.
Most of these trace back to water, which is why they are covered in detail on our chimney repair page.
Masonry damage you can see from the ground
- Crumbling, recessed or missing mortar joints. Repoint before water gets deeper into the stack.
- Flaking, pitting or spalling brick faces. Freeze-thaw damage — the brick is soaking up water and breaking apart.
- A cracked or crumbling crown at the very top. The crown is the chimney’s first line of defense; small cracks are cheap to seal, a failed crown is not.
- A chimney that leans, or a visible gap opening between the chimney and the house. A structural problem — stop using it and get it inspected. Your repair options short of a teardown are on our alternatives to a rebuild page.
Signs inside the firebox and flue
- Thick, tar-like or shiny black deposits in the flue. Stage 2 or 3 creosote — a real fire hazard. See the three stages on our chimney anatomy guide.
- Cracked or gapped flue tiles, or pieces of clay tile in the firebox. A failing liner; relining is usually the fix.
- A gas pilot that will not stay lit, or soot building on a gas unit. A venting or appliance issue for gas fireplace service.
What to do when you notice a symptom
Do not keep burning if you see a leaning chimney, a cracked liner, or any sign of a chimney fire. For everything else, the fix should follow a diagnosis rather than a guess: the symptom tells us where to look, and a camera inspection confirms the cause before anyone quotes a repair. Book an inspection, or see the full list of what we do on our services page.
Frequently Asked Questions
How do I know if my chimney needs sweeping?
Common signs are a smoky smell, smoke rolling back into the room, visible soot or tar in the flue, or simply a year passing since the last sweep. Once build-up reaches about one eighth of an inch, it is time.
Why does my fireplace smell, especially in summer?
Creosote left in the flue absorbs humidity and gives off a strong smoky odor in warm, damp weather. Sweeping removes the creosote, which removes the smell at its source.
Why is smoke coming into my house instead of going up the chimney?
It points to a draft problem: a blocked or dirty flue, a cold or undersized flue, or a missing cap allowing downdrafts. An inspection finds which one, and the fix ranges from a sweep to an insulated liner.
What do white stains on my chimney mean?
That white, crusty deposit is efflorescence, left behind as water moves through and evaporates out of the masonry. It is a reliable sign of a moisture problem that needs addressing before the brick deteriorates.
Is a leaning chimney dangerous?
Yes. A lean or a widening gap from the house signals a structural failure in the footing or masonry. Stop using the fireplace and have it inspected promptly.
What does a cracked flue tile mean?
The liner is the barrier that keeps heat and combustion gases away from the surrounding masonry and framing. A cracked or gapped tile breaks that barrier, which is both a fire and a carbon-monoxide risk, and usually calls for relining.
Can I ignore a small chimney leak?
No. Water is the number one enemy of masonry, and a small leak compounds every freeze-thaw cycle. A repair that would have been a cap or a crown seal becomes repointing or a rebuild if it is left.
How fast can you come out if I notice a problem?
Call and we will tell you honestly how soon we can get there. If you suspect an active chimney fire, call 911 first and stop using the appliance.
Written by Johnathan Mason, owner of Ace Chimney Service, Crystal Lake, IL — 29 years in chimney and fireplace work.
Published: October 3, 2026 · Updated: October 3, 2026
Noticing any of these signs? Call Ace Chimney Service at (815) 320-0883 or book an inspection online. We serve Crystal Lake and McHenry County seven days a week.