An Explanation of Creosote

Creosote is a common enemy of the chimney. While it is simply a part of owning a fireplace in the home, it is important to understand why you need to have creosote cleaned regularly. Regular chimney maintenance will keep creosote from causing a catastrophic fire in your home.

First of all, how does creosote get in your chimney in the first place? It is a naturally occurring by product of the low temperature burning of fossil fuels and wood. When wood, for instance, is burned in a fireplace, the temperature is too low to fully burn the oils in the wood. They escape into the chimney via smoke, and begins to cool. As it does this, it causes water, carbon and other volatiles to condense on the sides of the chimney flue. This condensation creates a black, tarry substance called creosote.

During the heavy use season, creosote can build up to several inches thick. This reduces the air flow necessary for safe chimney operation. It also keeps the wood from burning at a high temperature. If enough creosote has built-up, simply leaving the flue open for air flow can ignite a fire. This is because the highly flammable substance has come into contact with hot oxygen and ignited.

Here are some key things to keep in mind in order to avoid a creosote-induced fire:

  • Have your chimney regularly cleaned. At minimum, clean it annually.
  • Don’t use coniferous woods (spruce, pine, fir).
  • Make sure the wood is seasoned before burning. This means making sure the wood is dry inside as well as out.
  • Check the chimney throughout the burning season.

Don’t let creosote cause a fire that can be stopped by simple maintenance. That way, you can enjoy your fireplace safely, and for years to come.

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