Chimney Fire Prevention

Chimney fire prevention is an essential part of burning wood. On a freezing cold winter night when you are snuggled next to the warm wood stove and happen to hear the roar of what sounds like a freight train coming through the house, guess what, you have a chimney fire. A quick run outside to look at the top of your chimney will confirm this fact as there will be flames streaking out of the top of your chimney along with a rush of black soot deposits. The first thing you need to do is cut off all air to your woodstove by closing the chimney damper that may be open. This will starve the fire of oxygen and the flame will subside almost immediately. The second thing to do is call 911 and report that you have a chimney fire.  

Now that the chimney fire is out and there is no more danger of a secondary fire you have to ask yourself why was there a chimney fire. After all, the chimney is made of masonry which does not burn. The simple answer is because the chimney has not been recently cleaned. Dirty chimneys cause chimney fires, which can damage the chimney structure, destroy homes, and injure or kill people. If you are burning more that 2 or 3 cord of seasoned wood each year your chimney needs to be cleaned once a year. However, if you are burning large amounts of wood or non-seasoned wood your chimney needs to be cleaned more often.

Non-seasoned wood is wood that has more than 10% moisture by weight. It burns at a lower temperature than seasoned wood and produces large amounts of creosote that sticks to the sides of the chimney. As it dries it builds a web of dried creosote that is highly combustible. It is this dried creosote that burns in a chimney fire. It burns at a very hot temperature, as high as 2,000 degrees. As it burns it sucks oxygen from below through the open dampers on your stove. Normally chimney fires are very short in duration. As soon as the creosote is burned the fire is diminished and goes out. If the structure of the chimney is not damaged there is no secondary fire.

Creosote is easy to detect in your chimney. Use a mirror and look up the inside of the chimney. If the chimney is clean you should be able to see an unobstructed passage to the top of the chimney viewing a bright sky at the top. If the view is obscured it is because the chimney is dirty and requires cleaning.  Creosote will appear as black or brown honeycomb on the sides of the chimney liner wall. Conditions other than burning non-seasoned wood causes the buildup of creosote such as; restricted air supply and cooler-than-normal chimney temperatures will contribute to creosote buildup in your chimney. If the wood burns too slowly (cool) the chimney will remain cool causing a low draft which will not permit the venting of the smoke and waste particles out the chimney. This makes a cool smoldering fire and contributes to the creosote.

Chimney fire prevention is not difficult. As a DIY project here are some tips to avoid them:

• Use seasoned woods only. Seasoned wood is wood that is less than 10% moisture by weight.
• Build smaller, hotter fires that burn more completely and produce less smoke.
• Never burn trash in your wood stove such as cardboard boxes or wrapping paper.
• Install a stovepipe thermometer to help monitor flue temperature.
• Have the chimney inspected and cleaned on a regular basis.

Remember if you have a chimney fire close the chimney damper on the stove or stove pipe immediately. Once the fire is starved from the oxygen source it will go out on its own very quickly. Do not use your wood stove again until the chimney  has been leaned by a chimney sweep.