A chimney fire burns the creosote lining the flue, not the chimney itself, and it can be almost silent. Slow-burning chimney fires smoulder with little noise while cracking clay tiles and warping metal liners. Any chimney that has had a fire needs a Level 2 inspection with a camera before it is used again — the flue can look fine from the firebox and no longer be a sealed passage.
What is actually burning
Not the chimney — the creosote lining it. Creosote is a tarry condensate deposited as smoke cools on its way up the flue, and in its hardened glazed stage it behaves like fuel oil. Once it reaches ignition temperature it burns inside the flue at temperatures far beyond what the structure was built to contain.
The signs
A loud, continuous roaring, often compared to a freight train. Cracking and popping from inside the chimney. Dense smoke and an intense hot smell. Flames or glowing debris visible at the top of the chimney from outside.
A slow-burning chimney fire may produce none of those. It can smoulder with barely any noise, and the only evidence afterwards is damage found during an inspection: puffy or honeycombed creosote, cracked flue tiles, warped metal components, discoloured masonry.
What to do in the moment
Get everyone out of the house. Call the fire service. Do not stay to fight it, and do not go outside to look at the top of the chimney while it is happening.
If you can do so safely on the way out, close the fireplace doors or damper to starve it of air, and move anything flammable away from the hearth. Those are secondary to leaving.
Why the flue cannot simply be used again
This is the part people underestimate. A chimney fire routinely cracks clay flue tiles through thermal shock, opens joints between them, and warps or damages metal liners and connectors. The flue may look fine from the firebox and no longer be a sealed passage.
Once that seal is broken, the next ordinary fire can send heat and combustion gases into the wall cavity and the framing behind the masonry. A second fire in a chimney damaged by the first is how a flue fire becomes a house fire.
Any chimney that has had a fire needs a Level 2 inspection with a full camera scan before it is used again. That is not an upsell; it is the specific circumstance the Level 2 exists for.
The prevention is unglamorous
Burn seasoned wood. Do not damp a fire down to smoulder overnight. Have the flue swept when buildup reaches about an eighth of an inch. That is the whole list, and it works.
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Think you have had a chimney fire?
Do not light another fire until it has been inspected. Call us.
Related questions
Can I have a chimney fire without knowing?
Yes. Slow-burning chimney fires can smoulder with very little noise, and the damage is often only found later during an inspection.
What should I do first if I suspect one?
Get everyone out and call the fire service. Closing the damper helps, but only if you can do it safely on your way out.
Can I use the fireplace after the fire service leaves?
No. They make the situation safe; they do not assess the flue. It needs a Level 2 camera inspection first.
What damage does a chimney fire usually cause?
Cracked or displaced clay tiles, open joints, warped metal liners and connectors, and sometimes damage to nearby framing.
Does home insurance cover it?
That is between you and your insurer, but a documented inspection report with photographs is usually what they ask for.
How do I stop it happening again?
Seasoned wood, no smouldering overnight burns, and sweeping at the eighth-of-an-inch mark.
Written by Rick Lee, owner of Zenith Chimney Service, Geneva IL. Published September 14, 2026 · Last updated September 4, 2026.