Creosote is a part of a chimney professional’s day every day, but creosote is not an inevitable part of burning a fire in the fireplace. People often think that creosote buildup occurs whenever a fireplace is used, but this is not the case. There are actually many factors which are preventable that are the reason that creosote buildup occurs.

If you have a wood stove, a common problem which results in creosote buildup is a poorly designed wood burning stove. Until recently, air tight stoves were deemed the best for burning wood. These stoves are designed to allow wood to burn for a long time at a relatively low heat, meaning that the fire needs fueled less often but also provides an incomplete combustion. A large part of the wood is used not for producing heat but producing smoke, and since the flue system is relatively cool it condenses in the form of

creosote in the flue. By using a newer, EPA certified stove you can burn fuel more efficiently and reduce creosote buildup. You should not see a lot of smoke billowing out of your chimney. If you do, this means that your fire is not burning hot enough and therefore not very efficiently.

Chimneys that draw improperly are another cause of creosote. If the ratio between flue size and firebox is not correct, the products of combustion will not move up and out of the chimney as quickly as they should. When this occurs, the gases have a chance to cool off and condense on the walls, causing creosote buildup.

If you select the wrong type of wood to burn, no matter how efficiently you get the fire burning creosote will build up. Wood that is green or wet should not be burned. It releases excessive water vapors into the flue system which increases the rate at which creosote condenses in the flue system. Always burn dry wood. Dry wood releases less water vapor and makes for a more complete burn to reduce creosote buildup.

Creosote Modifier
When creosote buildup occurs, sometimes it is necessary to use creosote modifiers for easier removal.

Creosote buildup, especially once it has reached stage three and is glazed onto your flue system, is often hard to remove. Your chimney professional may recommend a creosote modifying spray or powder to change the state of the creosote. These actually modify the creosote so that it is easier to remove. If the creosote is glazed on it will chemically change it such that a standard brush is able to sweep the creosote away.

As you can see, creosote buildup is preventable. Conditions must be right in order for a chimney to draw properly, for the fire to burn at an appropriate temperature, and the wood you use must not be wet or green. Homeowners think that creosote is simply the result of burning fires, but this is not the case.

Clay Lamb

Clay Lamb is a Cincinnati Chimney Sweep contractor and the executive producer of the YouTube channel, podcast, and blog Ask the Chimney Sweep. He is also an award-winning educator and public speaker in the chimney and fireplace industry.

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Clay Lamb

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