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Creosote and the Types of Damage it Can Cause

Richmond VA Chimney SweepChimney creosote is a tar-like substance that causes damage to your chimney venting system and increases potential hazards associated with burning firewood in your fireplace. Some creosote is deposited inside your chimney lining each time you burn a wood fire. It is highly flammable and increases the risk of dangerous chimney fires and out-of-control home fires. Creosote is also the primary reason to schedule a chimney sweep for chimney cleaning on a routine basis.

What is Creosote?

Combustion byproducts are produced by wood fires and mostly go up the chimney, but some are left behind in the flue. Those byproducts contain smoke, gases, tar fog, unburned particles of wood, water vapor, and other materials. The residue that remains in the chimney lining is creosote. It is brown or black, and there are three different stages or forms of creosote. Each is hazardous but only one of the forms of creosote is easy to remove.

Basics of 3 Stages of Creosote

Different chimney conditions produce the different stages of creosote. Information about each follows:

  • Stage 1 creosote is mostly in the form of ashy soot, and it can easily be removed using a professional chimney brush. It is produced in a fireplace that has plenty of air to be used for the combustion process. The logs burned are properly seasoned, which means the moisture in the wood has sufficiently dried out over time. Also, smoldering fires are avoided.
  • Stage 2 creosote looks like shiny black flakes, about the size of cornflakes. This type of creosote doesn’t easily brush away, but professional chimney sweeps have the equipment and expertise to remove it completely. Air restriction is the primary reason Stage 2 creosote forms in a chimney. It is mostly common in fireplaces with glass doors.
  • Stage 3 creosote looks like tar poured into a chimney, and it is difficult to clean. It is not unusual for this type of creosote to be impossible to remove. In such cases, installation of a new chimney lining is recommended. Among the various conditions that can contribute to the creation of Stage 3 creosote are: The chimney is cold, possibly due to lack of proper insulation; green, aka unseasoned, firewood is burned; the flue is too large for the appliance installed in the fireplace; and the house is too airtight, causing a lack of needed air in the fireplace.

Types of Damage Caused by Creosote


Creosote can build up to the point that the flue is obstructed. This negatively affects operation of the chimney. It can also result in toxic gases being released back into the home. Carbon monoxide is among those gases, and it is known as the “Silent Killer” because it is invisible, odorless, and tasteless.

Chimney Fires

Hot embers can enter the chimney flue and cause the flammable creosote to catch fire inside the chimney. Chimney fires can be extremely dangerous. When they are intensely hot, they can damage the chimney lining and spread the flames into the home. Slow-burning chimney fires are more common and also potentially extremely dangerous. They could cause unseen damage to the flue that can lead to a house fire at a later time. Chimney fires are especially dangerous when Stage 3 creosote is in the flue because the fires are more persistent, stoked by the presence of the most stubborn form of creosote.

Flue Damage

Creosote has corrosive qualities. If the creosote and soot deposits are not routinely removed, corrosion of the flue system can occur. If moisture is combined with the toxic substances in creosote, it can cause deterioration of the flue lining. When a chimney lining has even the smallest crack in it, combustible parts of the home are exposed to extreme temperatures that can result in a house fire. Toxic fumes can enter the home, as well.

Odors and Health Problems

Chimney creosote in your flue can cause a foul odor in your home, especially during humid summer months. The presence of the sooty substance can also lead to respiratory problems, particularly in the very young and old, who might be more susceptible to respiratory issues.

Chimney Inspection RichmondContact us at Chimney Saver Solutions if you need a chimney inspection or chimney cleaning. Fire safety experts at Chimney Safety Institute of America (CSIA) recommend that homeowners have the creosote removed from their chimney every year. Call 804-440-5000 today to schedule creosote removal with the most trusted chimney service company in the Richmond area.

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