By Johnathan Mason, Ace Chimney Service.
Not every chimney fire is dramatic. Some announce themselves with flames above the roofline; many burn slowly and quietly and are discovered later by a sweep who finds the damage. Both do harm. Knowing the signs is genuinely useful to any Algonquin household that burns wood.
The signs while it is happening
A loud, low rumble often compared to a freight train or a low-flying aircraft. Sharp cracking or popping from inside the chimney. Dense smoke with an unusually strong, hot smell. Flames or glowing fragments visible above the chimney top. A section of the flue or connector pipe that starts glowing. If any of that occurs, the fire is in the flue, not the firebox.
What to do
Get everyone out of the house and call 911 from outside. Do not stop to investigate and do not go on the roof. If you can do it in seconds on the way out, closing the appliance’s air controls or the glass doors reduces the air feeding it — but only if it costs you no time. People come first, always. Let the fire service confirm it is out; a chimney fire can travel inside a wall and reignite hours later.
The quiet kind
A slow chimney fire may never be noticed from the living room. We find the evidence afterwards: creosote that has puffed up into a honeycombed, crusty texture, discoloured or warped metal, cracked flue tiles, a damaged or displaced cap, and creosote flakes on the roof. That is why a flue that has had a fire is not safe to use until it has been inspected, whatever it looks like from below.
Afterwards, the flue is a different flue
Heat cracks clay tile and opens joints. Those cracks are a direct path for the next fire’s heat to reach framing, which is how a second event becomes a house fire. After any suspected chimney fire the correct step is a Level 2 inspection with a camera scan, and if the liner is compromised, relining before the fireplace is used again.
Prevention is short and unglamorous
Burn dry, seasoned wood. Do not smoulder a fire down overnight for warmth — low, oxygen-starved burns are what deposit creosote fastest. Never burn cardboard, wrapping paper, or manufactured logs in quantity. And have the flue swept and inspected annually, because removing the fuel is the only reliable prevention there is.
Ace Chimney Service has 29 years in this work, is insured and bonded, gives the price up front, and covers Crystal Lake and McHenry County seven days a week from 7 AM to 7 PM. Call (815) 320-0883 or see our services.
Frequently asked questions
What does a chimney fire sound like?
Most often a deep roaring or rumbling, sometimes with cracking and popping. Slow-burning chimney fires may make no noticeable sound at all.
Should I throw water on it?
No. Leave the house and call 911. Water into a hot flue can cause rapid steam expansion and crack the masonry.
Can I use the fireplace after a small chimney fire?
Not until it has been inspected. Even a brief fire can crack tiles and open joints that let the next fire reach framing.
How do sweeps know a fire happened?
Puffed, honeycombed creosote, heat-damaged tile, warped metal, and creosote debris on the roof are the usual evidence.
What causes chimney fires?
Ignition of accumulated creosote, which builds fastest from wet wood and slow, smouldering fires.
Are chimney fires possible with gas?
Creosote fires are a wood-burning issue, but gas appliances have their own venting hazards, including blockages and carbon monoxide.
Does a chimney fire always damage the chimney?
Assume yes until an inspection says otherwise. Damage is frequently internal and not visible from the room.
Will annual sweeping prevent one?
It removes the fuel, which is the single most effective step. Combined with dry wood and hot, clean burns, the risk drops sharply.
Published September 8, 2026