Quick answer
Creosote is a flammable, tar-like residue that forms when wood smoke cools and condenses on the inside of a chimney. It builds in three stages — powdery soot, crunchy flakes, and a hard shiny glaze. All stages are flammable, and buildup is the leading cause of chimney fires.
The three stages of creosote
- Stage 1 — soot. Dry, powdery and easy to brush out during a regular sweep.
- Stage 2 — flaky. Black, crunchy flakes. Still removable with professional rotary tools.
- Stage 3 — glazed. A tar-like, shiny coating that hardens on the flue. It's very difficult to remove and requires special chemical treatments or rotary removal tools. It burns extremely hot.
What causes heavy creosote?
- Burning wet or unseasoned wood
- Smoldering, low-oxygen fires (damper or stove air mostly closed)
- Oversized or uninsulated flues that keep smoke cool
- Cold exterior chimneys
How to reduce creosote
- Burn only dry, seasoned hardwood (split and dried at least 6 months)
- Burn hotter, smaller fires instead of slow smoldering ones
- Make sure the flue is correctly sized and lined
- Have the chimney swept and inspected every year
More questions
Do creosote sweeping logs work?
They can make light deposits easier to remove, but they don't remove creosote by themselves and are not a substitute for a professional cleaning.
Does burning pine cause creosote?
Any wet or unseasoned wood creates more creosote. Well-seasoned softwood is fine; wet wood of any kind is the real problem.
Need a professional?
Chimney Champs provides chimney cleaning & sweeping across PA, NJ, DE, NY and CT. Call (856) 300-9215 for a free estimate.
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