What a chimney fire is
A chimney fire is creosote, the tar-like residue that wood smoke leaves on the flue walls, catching fire inside the chimney. It can burn far hotter than the fire in the fireplace, hot enough to crack flue tiles, damage mortar and, in the worst cases, reach the framing of the house.
They are most likely in flues that haven't been swept, and in fireplaces that burn a lot of short, cool fires, which is exactly the pattern most Southern California homes have.
The loud signs
A fast-burning chimney fire is hard to miss:
- A loud roaring or rumbling, often compared to a freight train or a low-flying plane
- Popping and cracking from inside the chimney
- Dense smoke, or a strong hot, acrid smell
- Flames or sparks shooting out of the top of the chimney
- The chimney breast or the wall around it becoming hot to the touch
- A strong pull of air into the fireplace
What to do if you think it's happening
- Get everyone out of the house
- Call 911
- If you can do it safely, close the fireplace doors or the damper to cut off air to the fire
- Don't throw water into the firebox, as the steam and sudden cooling can crack hot masonry
- Don't use the fireplace again until the chimney has been inspected
Even if the fire seems to burn itself out quickly, have the fire department check the house and the attic. A chimney fire can spread into the framing without being visible from inside the room.
The quiet signs
Slow-burning chimney fires often go unnoticed. The signs they leave behind include:
- Puffy, honeycomb-looking creosote in the flue, quite different from flat glaze
- A warped or discoloured damper, or a cap that looks heat-damaged
- Cracked or collapsed flue tiles, or pieces of tile in the firebox or on the roof
- Roofing damaged by hot debris near the chimney
- Smoke escaping through cracks in the masonry
Any one of these is a reason to stop using the fireplace and have it inspected.
Why an inspection afterwards matters
After a chimney fire, the national standard calls for a Level 2 inspection, which includes a camera survey of the whole flue. The damage that matters most, cracked tiles and gaps in the liner, is inside the chimney where nobody can see it. Lighting another fire in a damaged flue lets heat reach the masonry and the house.
A dated report with photographs is also what you'll want if you make an insurance claim.
Want a professional to take a look?
OakStone Chimney Solutions serves 15 cities across Los Angeles County, 24 hours a day. Estimates are free and there is no obligation.
Frequently Asked Questions
It's rare, since gas produces almost no creosote. It can happen if the fireplace once burned wood and the flue was never swept after the conversion.
Have the chimney swept when buildup reaches about an eighth of an inch, burn only dry seasoned wood, avoid long smouldering fires, and never burn trash, cardboard or treated wood.
Fire damage is commonly covered by homeowners policies, but every policy differs. Check yours, and keep the inspection report and photographs.