Each year in the US, about 25,000 fires ignite in the chimney resulting in $125 million in property damage. Chimney fires most commonly occur when creosote deposits that have build up in the chimney ignite.
What is Creosote?
As the smoke and other by-products of combustion travel up the chimney and cool slightly, condensation allows residue to coat the inner walls of the chimney or chimney liner. This residue is called creosote. Creosote is extremely flammable. Creosote deposits prevent the chimney from operating efficiently and venting properly which leads to even more creosote accumulation.
How to Identify and Remove Creosote
Creosote is a standard byproduct of using a stove or fireplace regularly. However, creosote requires regular removal to prevent a dangerous chimney fire. The risk of a chimney fire increases with greater accumulation of creosote. Creosote is categorized in 3 stages.
First Degree Creosote – is mostly made up of soot with a flaky, thin texture. This type of creosote is easily cleaned away with a flue brush. Chimney cleanings and inspections should be scheduled at least once per year with a professional chimney sweep.
Second Degree Creosote – forms as a result of restricted airflow. This type of creosote looks like shiny flakes. Creosote at this stage contains bits of hardened tar and requires chemical solvents and a specialty tool called a rotary loop for removal.
Third Degree Creosote – contains black, glossy tar deposits in high concentrations. Fresh creosote at this stage may feel sticky. Otherwise, creosote that has been repeatedly heated and “baked on” will have a hard and shiny appearance. This level of creosote takes a lot of effort to remove, and it is sometimes more convenient to replace the entire chimney liner than to remove this type of creosote.
Detecting A Chimney Fire
Chimney fires can burn explosively making loud cracking and popping noises, sometimes rumbling like a freight train, producing lots of dense smoke, and giving off an intense, hot smell. This type of fire often spreads to other combustible areas of the home. Sometimes, chimney fires go undetected.
Here are 8 signs you have had a chimney fire:
- "Puffy" creosote, with rainbow colored streaks, that has expanded beyond creosote's normal form
- Warped metal of the damper, metal smoke chamber, connector pipe, or factory-built metal chimney
- Cracked or collapsed flue tiles, or tiles with large chunks missing
- Discolored and distorted rain cap
- Creosote flakes and pieces found on the roof or ground
- Roofing material damaged from hot creosote
- Cracks in exterior masonry
- Evidence of smoke escaping through mortar joints of masonry or tile liners
Creosote can be successfully managed by good habits to limit creosote accumulation and regular maintenance to keep the chimney in optimum condition. Put a freeze on chimney fires by following these steps:
1. Burn Wisely
Burn only dry, seasoned firewood containing less than 20% moisture content. Avoid burning trash, wrapping paper, accelerants, or processed and treated materials which can release chemicals in the chimney and feed creosote deposits.
2. Ensure Steady Air Flow
If air supply is restricted by closing glass doors or failing to open the damper wide enough, it will take longer for the chimney to expel smoke and other flue gases resulting in increased levels of creosote left behind. This will keep your chimney cleaner and safer in between inspections.
3. Follow a Regular Schedule
Hire a professional sweep to clean and inspect the chimney at least once per year. Keeping up with regular cleanings will help to catch creosote in earlier stages that are faster, easier, and less expensive to remove. You can search for a certified chimney sweep in your area HERE.