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A responsible wood burner is aware of the risks that come with burning wood and knows how to manage them. One of the risks you should keep in mind is the build-up of creosote in the flue. In this knowledge article we explain what creosote is, why it is dangerous, and how you can prevent it.

What is creosote?

Creosote is a flammable, tar-like substance that forms when wood burns incompletely. During combustion, unburned particles can cling to the inner walls of the chimney, creating creosote deposits. This build-up can range from a sticky layer to a hard, glossy coating.

Is creosote dangerous?

Yes, creosote is dangerous. It is highly flammable and, when it accumulates, can cause chimney fires. During such a fire, temperatures can reach 1000 degrees Celsius or more, which may lead to severe damage to your home. A chimney fire can also push smoke back into the living space.

How do you prevent creosote in your flue?

Naturally, you want to prevent creosote from collecting in your chimney. You do this by promoting complete combustion in your wood stove. Here are a few guidelines to support complete combustion and minimise creosote formation:

• Use dry wood. Burn only dry, well-split wood with a moisture content below 20 percent. Damp wood produces more smoke and creates creosote. You can read more about finding dry firewood in our dedicated article.
• Ensure sufficient air supply. Good airflow supports complete combustion and reduces the formation of creosote.
• Burn at a high temperature. Keep the flue gas temperature above 120 degrees Celsius to prevent condensation and creosote build-up.
• Have your chimney cleaned regularly. Have it professionally swept at least once a year to remove deposited creosote and reduce the risk of chimney fires.
• Use proper fire-starting technique. Apply the top-down fire method, where the fire is lit from the top. This results in cleaner combustion and less smoke.

Top-down fire method

Removing creosote

Even with the right habits, some creosote can still form. It is therefore important to remove deposits in time. The most effective solution is an annual cleaning by a certified chimney sweep. With proper maintenance of your chimney, you reduce the risk of chimney fires and ensure safe and efficient combustion.