I use the word avoid because you can’t prevent creosote buildup, but you can slow it down. First, I’m going to explain what creosote is and how it accumulates within your chimney’s flue. Then I’ll explain how dangerous it is to let creosote linger and build up over time within the flue. Lastly I’ll show you a few different ways to reduce the amount of creosote buildup you see year after year. Ready? Let’s get started.

What is Creosote?

Creosote is a black, tar-like substance that collects on the inner walls of the flue. It is ultimately the byproduct of smoke and unburned particles of wood cooling, meeting condensation, and falling back onto the inside of the chimney. You will always see a bit of black when you shine a light into the chimney. Learn to properly identify creosote so you can keep an eye on the thickness as it builds up.

The unburned particles that make up creosote are highly combustible and may build up enough to start a chimney fire. Chimney fires have the potential to start structural fires, which puts your entire home at risk.

  • Burn Seasoned Wood: Never burn green wood or wet wood. Wet wood and wood that still contains sap (unseasoned) create condensation as smoke rises in the flue. This creates the perfect atmosphere to allow creosote to build up within your chimney.

Seasoned wood is wood that is completely dry, or contains no more than 20% moisture. You can purchase a device which measures the amount of moisture in the wood before you burn it, or you can let wood dry for several days after you bring it into the house before burning it.

Hardwoods burn hotter and more efficiently than softwood. Always look for oak, maple, ash, or birch to burn in your fireplace, and make sure they have been seasoned for at least six months to a year.

  • Avoid Slow Burns: Slow burns, or smoldering fires, create more smoke and do not burn as hot as they should to push the smoke up the flue and out of the top of the chimney.
  • Use Highly Efficient Burning Practices: Never use flammable fluids to start your fireplace fire. They create more smoke and often produce a smell that lingers for hours. Reduce smoke by not using cardboard or newspaper for starting fires; cut your normal firewood into small strips to use as kindling instead. Burn at a steady temperature that promotes fireplace and chimney health.

Reduce the Likelihood of Chimney Fires Due to Creosote Buildup

Schedule a yearly chimney inspection and cleaning to prevent creosote buildup year after year. Your chimney may require an additional cleaning throughout the year if you notice creosote buildup 1/8” to 1/4” thick. Never let creosote build to thicker than 1/4” thick, as this puts you at a higher risk of chimney fire. Call me any time to discuss chimney safety or schedule an appointment for a chimney inspection or cleaning.