The Three Types Of Creosote

Creosote BuildupThe Three Types of Creosote, from Least to Most Hazardous

Did you know that whenever you burn wood in your fireplace, creosote is deposited in the chimney lining? “Creosote” is the name used for wood-burning byproducts, and it consists of a mix of creosote, tar, and soot. Creosote buildup in your chimney has three degrees, each different from the other and each more difficult to clean and potentially more hazardous than the previous degree. Possibly the most important reason to get an annual chimney cleaning and inspection is to prevent chimney fires caused by creosote.

1st Degree Creosote

The type of buildup you want in your chimney liner is first degree creosote. This type has high soot content and can be easily removed with a basic chimney brush.

First degree creosote is produced when the flue is warmed by the fire’s heat, there is good wood combustion, and the fire gets plenty of air. The best way to achieve good wood combustion is to burn only seasoned firewood; when firewood is seasoned, it has low moisture content. Houses today are often sealed too tightly, which can cause the air supply in the fireplace to be restricted, which in turn causes smoke to enter the home and prevents the flue from warming properly.

 2nd Degree Creosote

A chimney which has a restricted amount of incoming air sets up the right conditions to produce the second degree of creosote. Restricted air is commonly caused by fireplaces and wood stoves that have glass doors. This degree of creosote looks like glistening black flakes. The flakes contain hardened tar, and they are not easily brushed away.

Removing creosote is essential for safety reasons, but achieving it is only easy with first degree creosote. A rotary loop is most often used to remove second degree creosote. This equipment consists of a stainless steel cable attached to a hub which has metal rods that are turned by a special type of powerful drill. Some people mistakenly believe that a rotary loop damages their chimney liner, but what really happens is that the liner is already damaged and the cable knocks it loose.

3rd Degree Creosote

Third Degree Creosote

Third degree creosote is extremely concentrated fuel that looks like tar running down
or coating the inside of the chimney. The creosote hardens and is repeatedly recoated. If the creosote in the liner catches fire, third degree creosote may burn up, but it usually does not. Instead, the creosote partly boils and partly burns, leaving a light-weight “sponge” that is simple to remove. However, if it is not cleaned and creosote fills the spongy substance, your chimney can end up with more than 100 pounds of creosote and a highly combustible chimney.

Some of the conditions which cause third degree creosote are:

  • When combustion is incomplete and/or the flue isn’t sufficiently warmed
  • The chimney is not insulated or is cold for some other reason
  • Unseasoned wood is being burned
  • The house is sealed tightly enough that there is an insufficient amount of combustion air
  • The flue is oversized

Cleaning third degree creosote is very difficult, and the best course of action is often to simply replace the chimney liner. Options for removing the most difficult degree of creosote include using a rotary head with chains and using chemical creosote removers.

Our professional chimney sweeps have the knowledge and skill to remove all degrees of creosote, but we highly recommend cleaning the chimney annually, to avoid the dangers and difficulties associated with third degree creosote.


Chimney Solutions, Inc.
1155 McFarland 400 Drive, Alpharetta GA 30004
Office 770-255-1300

Chimney Sweep / Chimney Repairs / Chimney Liners / Fireplace & Stove Service
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Chimney Solutions
1155 McFarland 400 Drive AlpharettaGA30004 USA 
 • (770) 255-1300
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