Over 24,000 house fires starting from the chimney occur every year in the United States alone. In some cases, only the chimney is affected, but in others the entire house is destroyed. The main cause of such fires is the buildup of creosote in the flue. It poses extremely serious threat which must not be ignored. Effective prevention is possible.
How a Fire Can Start
Creosote is fine powder which contains tar particles and soot particles. It is a byproduct of wood burning. Under certain conditions, it builds up in the flue lining of the chimney. It can take several different forms. It can appear as sticky black tar. It can have gray powdery appearance. It can also be hard and shiny. The latter so called glazed form is the most combustible at all.
As the deposit of creosote builds up, it makes the passage for the hot air coming out of the fireplace smaller. When the hot air, which is under higher pressure, gets into contact with the deposit, combustion occurs and a fire starts. Often, the fire begins with a loud popping or cracking sound. It can be heard inside the house and by people in the neighborhood. In such situations, it is crucial for everyone on the property to leave immediately and for the fire brigade to be called. This is because in minutes, the room can get filled with dense smoke which is extremely dangerous for people and pets. The fire can easily crack the flue and the entire chimney open and spread to the other structures of the building.
In some cases, small fires can burn occasionally in the chimney without the people inside paying much attention to them. They usually make little smoke and produce unpleasant odor which is not particularly strong. Such fires can cause considerable damage to the chimney.
Creosote Accumulation Risk Factors
When wood burns, it produces fine tar and carbon powder particles which are carried up the chimney by the hot air. Since the flue lining is much cooler than this air, condensation occurs and the particles get accumulated on the walls. This is how the creosote deposits get formed.
There are some conditions which stimulate the building up of this combustible compound. When the chimney’s temperature is very low, creosote gets accumulated more quickly. This can also happen if the air supply to the chimney is restricted because of poor ventilation of the structure. The use of unseasoned wood is also a major risk factor. The accumulation of creosote can be speeded by too big flue serving a smaller fireplace. In such cases, draft is created and the flue surface becomes much cooler.
The best course of action is to eliminate any factors which stimulate the building up of creosote. In this way, the process will become much slower and the risk of fire will be reduced. The most important thing, however, is to have the chimney cleaned fully on a regular basis. This will help to lower the risk to the very possible minimum.
Do not let creosote build up in your chimney. Take action to prevent house fire now.