Creosote build up like this is a major cause of fireplace odors.

Creosote, a buildup of  the byproducts of combustion, can cause odor in your chimney which can permeate through your entire home. It takes only one use of your fireplace for a small amount of creosote to build up in your flue system, and when conditions are right the smell of the creosote can enter your home. The conditions which I am talking about include any which cause a down draft to occur. If you have negative pressure in your home and your home’s windows and doors are too air tight to permit any air to enter, air can be drawn down the chimney to make up for the lost air, bringing with it the odor of creosote.

Having your chimney cleaned can significantly reduce odor issues in your home by physically removing creosote, however, not all creosote can be removed by chimney cleaning equipment. Stage three creosote which has been glazed on can have odors and cannot be removed by most chimney cleaning equipment, instead it must be chemically modified in order  to be removed. If your chimney professional tells you that your chimney has glazed creosote, he will often recommend using a creosote modifying chemical such as Anti-Creo-Soot or Cre-Away, which will change the chemical composition of the creosote such that it is

ACS Spray Creosote Modifier
Anti-Creo-Soot helps to modify existing creosote such that it is easier for a chimney professional to remove.

in a form which can be swept away easily.

Using these chemicals is essentially painless and involves very little work on your part. Anti-Creo-Soot is a spray which is non-toxic and environmentally safe. During low fire conditions, spray this product into the firebox. It will help to convert creosote and soot into a harmless ash which can be easily removed from the fireplace. Anti-Creo-Soot is available in 32 oz. spray bottles and 1 gallon refill containers. Cre-Away is a powdered creosote modifier as opposed to a liquid spray. This product is

Creosote Modifier
Cre-Away is a creosote modifier which neutralizes creosote, eliminating its odor, while making glazed creosote easier to remove.

specifically designed to help to removed glazed creosote from the inside of your flue system. This product has a long straw which the product comes out from when the bottle is squeezed so that it will penetrate up into the flue system. Cre-Away helps by neutralizing the existing creosote so that it is less acidic on your chimney’s flue tiles and also breaks down the glazed creosote so that it can be removed.

When creosote is easier to remove, it is easier to eliminate the odor that creosote causes. Similarly, neutralized creosote loses a lot of its odor when it is neutralized as opposed to its natural, non-neutralized state.

Clay Lamb
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3 thoughts on “Creosote Causes Chimney Odors

  1. what causes creosote .is it ,not enough draft or fire not big enough .
    I get wet creosote down my metal pipe at wood burner.

  2. Mark,
    Creosote is caused by incomplete combustion of the wood being burned. You asked if this could be a draft issue, and yes it is possible. If there is a poor draft, the particles and gases can build up on the walls of your chimney. It’s also possible that the top screen is clogged preventing a good draft. There are three stages of Creosote. The wet creosote you mentioned is caused by one of the three stages, and it’s liquefying and dripping back down the chimney. We have some excellent videos and articles on Creosote, that I think would help you better understand in more detail. There are several that I suggest to you based on your question.

    How to Remove Creosote Buildup (article)

    Creosote and Chimney Fires (article)

    Chimney Creosote Removal (video) this has some great pictures.

    These are just a few that cover Creosote. You can find these and more by clicking on the tab Chimney, and the categories Chimney Cleaning and Sweeping , as well as Chimney Creosote Problems.

    Burn Safe and Warm,

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