What Causes Creosote?

Simply put, creosote is the by-product of burning wood.

And simply put, the cause of creosote is from smoke, water vapor, gases, unburned wood particles, hydrocarbon, tar fog and minerals that all go up into the chimney to exit the home. These particles are hot when they rise, and as they rise in the cooler chimney, condensation occurs. This causes residue known as creosote to stick to the walls of the chimney.

The chimney serves to exhaust the by-products of combustion or fires that are had in the fireplace. The chimney also serves to create breathability in the home. That’s right — the majority of the rest of your home, as far as you know or would have it in a perfect world, are air-tight when not opened (windows, doors, etc.), so the gases from the furnace and the healthy circulation of air is helped along by the chimney (drawing air up and out of the chimney).

The by-products of combustion, or a fire, include water vapors, gases and other unburned particles, be it wood, cardboard, or documents that no one should ever find. It will obviously be cooler, as those by-products are drafted up and out of the top of the chimney. As they do they begin to stick to the walls of the chimney’s flue system. The residue that is left behind is what we call creosote. Sounds harmless and normal, but that tar-like substance can harden and is actually highly flammable.

The folks over at the Chimney Safety Institute of America also let us know that a restricted air supply, unseasoned wood, and cooler than normal chimney temperatures are all factors that can accelerate the buildup ad cause of creosote on chimney flue walls (whether those are clay flue-tiles or a stainless-steel liner). Reignited creosote is extremely dangerous and can cause chimney fires, leading to structural damage with potentially catastrophic results, such as serious injury or death. We don’t mean to sound fatalistic here, but the reality is a chimney that has not been swept and inspected annually is a huge liability to the safety of your family and friends.

It is recommended by industry professionals to have the chimney swept and inspected at least once annually for many reasons, one being to help eliminate the cause of creosote. As we like to remind everyone, it’s very important to keep your chimney and fireplace in good condition.

Haven’t had your chimney swept or inspected in your Nashville home this year? Give us a call at (615) 823-8268. All of our sweeps have been certified by the Chimney Safety Institute of America.