A Fine Mess
Chimney fires are often dramatic events, with flames and cinders leaping high enough to come to the attention of neighbors and passersby. But they're not all like this. They can also burn quite slowly if they aren't being fed by much air or fuel. These sleeper fires are no less dangerous than the more visibly dramatic ones. They still reach high temperatures and can damage the chimney and nearby combustible parts of the house. The heat can be so intense that it can actually pick the mortar out from between bricks or stones.
Most chimney fires happen for one simple reason: improper usage and care of wood-burning appliances like fireplaces and woodstoves. (Faulty installation is another key reason, but it ranks a distant second to the first.) We'll talk about proper usage and maintenance in a minute. First, let's address the problem at hand.
A roaring sound—some people describe it as sounding like a freight train or a low-flying airplane—is typically the first indication of a chimney fire. If you hear this sound, and it's growing louder, you have every reason to believe there's a fire raging in your chimney.
Clouds of black smoke and sparks pouring out the top of your chimney are other indications of a chimney fire. If it's a big fire, flames can leap several feet above the top of the chimney.
If you see or hear any of this, here's what to do:
Call the fire department. The fire could be out before firefighters arrive, but it's a good idea to call them anyway.
Get everyone out of the house.
Close the damper or the air inlet controls to the fireplace or stove. This will limit air supply and reduce the fire's intensity.
Grab your fire extinguisher (you do have one, right?). Open the door to the fireplace or stove just enough so you can insert the extinguisher's nozzle. Shoot the contents of the entire canister inside and shut the door. If you don't have a fire extinguisher, baking soda or salt pellets work, too. But you'll have to use a lot of either substance. What you don't want to use is water. It could make things worse by causing more steam and gas to enter the chimney, which could crack or warp it.
Go outside. If the water to your hose connections is still turned on, wet down the roof and the area around your house. This will lessen the chances of sparks igniting other combustibles like shrubs and trees. Keep the water away from the chimney—wetting down a hot chimney could cause it to crack or even collapse.
In the Nick of Time
A quick way to snuff out a chimney fire is to use a chimney-fire suppressor. Available under several brand names—Chimfex Fire Suppressor is one—these flare-type devices snuff out flames by filling the chimney with a mixture of gases that rise up the chimney and cut off the oxygen supply to the fire. If you use your fireplace regularly, it might be worth keeping several of them around.
Don't go inside your home until the fire department tells you it's safe to do so. When you do, don't be surprised if things don't look too good. A large chimney fire can dump a ton of smoke and soot inside. There might be water damage to deal with as well. For information on putting your house back in order, turn to Clearing the Smoke after a Fire.
Don't use your fireplace or woodstove until you've had a professional such as a fire-place or woodstove installer or a chimney sweep come out and inspect the chimney. Chimney fires can cause a lot of damage to the chimney structure, including cracks and holes in the chimney wall, the flue, the flue pipe, and the flue liner. If the damage isn't repaired, any subsequent fires could move beyond the flue and engulf adjoining areas.