By Daniel Watkins, Noble Chimney Sweepers.
Most chimney fires are never reported, because most of them go out on their own before anybody realizes what happened. A homeowner in Mokena hears a roaring sound for a couple of minutes, it stops, the fire in the fireplace looks normal again, and life goes on. The damage upstairs is done, and it stays there until somebody looks. This post covers what a chimney fire looks and sounds like while it is happening, what to do in that moment, and the physical evidence it leaves behind for the next inspection to find.
What it is like while it is happening
A chimney fire is the creosote lining the flue igniting. Depending on how much fuel is up there and how much air reaches it, it presents in two very different ways.
The loud version
A fast, oxygen-fed chimney fire is unmistakable. People describe a low roaring or a sound like a freight train or a jet engine overhead, sometimes with cracking and popping. From outside, dense smoke and sparks or flames come out of the top of the chimney. It is loud enough that neighbors notice.
The quiet version, which is more common
A slow-burning chimney fire gets far less air and makes almost no noise. There may be nothing but a hot, dense smell and a fire that seems to be drawing oddly. These are the ones that go unnoticed, and they are not less serious. A slow burn holds high temperatures against the flue and the surrounding structure for a long stretch, which is exactly the condition that damages tile liners and transfers heat to nearby framing.
What to do if you think one is happening
Get everyone out of the house and call the fire department from outside. That is the first and only priority. Do not go on the roof and do not open the cleanout to look. If you can do it safely on the way out, closing the glass doors or the damper reduces the air feeding the fire, and some homeowners keep a chimney fire extinguisher stick for this, but none of that replaces evacuating and calling. After the fire department clears the house, the chimney should not be used again until it has been inspected internally. A flue that has had a fire has to be assumed damaged until somebody has actually looked inside it.
The evidence a past fire leaves behind
This is what we look for when a homeowner says they are not sure whether something happened. Several of these you can spot yourself from inside the house or from the ground.
Puffy or honeycombed creosote
Creosote that has burned and expanded looks completely different from normal buildup. Instead of flat, shiny, or flaky deposits, you get a puffed, spongy, honeycomb-textured material, often lighter in color, sometimes described as looking like burnt marshmallow. It is the clearest single indicator there is.
Cracked or displaced flue tiles
Clay tile liners crack when they heat fast and unevenly. In a flue that has had a fire, you find cracks running through tiles, chunks of tile in the smoke chamber or at the cleanout, and sometimes tiles pushed out of alignment at the joints. This is only visible with a camera scan, and it is the finding that most often turns into a relining job. Our chimney relining page explains what that involves.
Heat damage at the top and outside
Look at the chimney from the ground. A warped, discolored, or partly melted rain cap, or a cap with the mesh burned or distorted, points to serious heat coming out the top. So does creosote that has run down the outside of the crown, discolored exterior masonry, or roofing shingles near the chimney that look scorched or curled on the chimney side.
A warped damper or scorched smoke chamber
A cast-iron damper plate that has warped out of shape, or one that suddenly will not seat properly when it used to, is a heat sign. So is fresh scorching or spalled brick visible in the smoke chamber above the firebox.
Cracks in the exterior masonry or an odd smell in the attic
Vertical cracking in the chimney masonry outside can follow a fire that expanded the structure. And a persistent burnt smell in an attic or upstairs closet near the chimney chase deserves a look, because heat transferred through a cracked flue reaches wood framing.
Why it matters more than the fire itself
The danger of a chimney fire is usually not the fire you heard. It is the next one. A cracked liner has an open path from the flue to the framing that surrounds it, so a fire that would have been contained now has somewhere to go. That is why a chimney is taken out of service after a suspected fire until it has been inspected, and why an inspection after a fire is a camera scan of the full flue rather than a look with a flashlight. Our chimney inspection page describes what that scan covers, and the surest way to avoid the whole situation is keeping the creosote load down in the first place with regular chimney sweeping.
Noble Chimney Sweepers is certified, bonded and insured, owner-operated, and I have 14 years in this trade. If you heard something you cannot explain, stop using the fireplace and call us. We will tell you what we find and give you the price up front before anything gets done. We are at (708) 432-5747, seven days a week, 7 AM to 7 PM.
Frequently asked questions
Can a chimney fire happen without me knowing?
Yes, and that is the usual case. Slow-burning chimney fires get little air, make almost no noise, and leave the fire in the fireplace looking normal. The evidence is up in the flue, which is why the damage is often found later during an unrelated sweep.
How hot does a chimney fire get?
Hot enough to crack clay tile liners and to warp cast iron, which is well past the temperature a chimney is built to handle in ordinary use. The exact number varies with the fuel load and the air supply, so the practical answer is that any suspected fire means the flue gets inspected before the next burn.
Is a stainless steel liner immune?
No. A properly sized and installed stainless liner handles heat far better than aged clay tile, but a chimney fire can still buckle, discolor, or open the seams of a liner, particularly a thin single-wall product. Any liner that has been through a fire gets inspected the same way.
Do I have to call my insurance company?
That is a decision between you and your insurer, but the documentation matters either way. Ask for a written inspection report with photos of what was found. If there is structural damage to the liner, having that record from the start is far better than reconstructing it later.
What if the fire department already came out and said it was out?
They put the fire out, which is their job, and that is separate from assessing the condition of the flue. The department will normally tell you not to use the chimney until it is inspected. Take that at face value and get a camera scan before the next fire.
Can I just have it swept and start using it again?
A sweep removes the fuel but does not tell you whether the liner is intact. After a suspected fire you want the internal scan, not just the cleaning. If the scan is clean, you are back in service. If it is not, sweeping a cracked flue has not made it safe.
Does burning hotter fires prevent this?
Burning hot, dry, seasoned wood produces far less creosote than smoldering damp wood, so it reduces the fuel that a chimney fire needs. It does not remove deposits that are already there, and a deliberately overfired stove creates its own problems. Fuel control plus regular sweeping is the combination that works.
How long after a fire can I find the evidence?
Indefinitely, until somebody sweeps or reveals it. Puffed creosote, cracked tiles, and a warped damper do not repair themselves, so a scan will still show a fire from several seasons ago. That is often how we date a problem a homeowner never knew about.
Published September 23, 2026