Creosote Buildup and Chimney Cleaning

Soot vs. creosote vs. glazed deposits

• Soot: loose, dry, and powdery, usually removed with brushes and a vacuum.
• Creosote: may be flaky or tar-like, sticky, and thicker. It is combustible, which is why buildup matters.
• Glazed or hardened deposits: shiny, hard layers that can be difficult to remove with standard brushing. They can require a different approach and an assessment.

The industry often describes creosote in stages, with the later stages more difficult. A stage cannot be judged over the phone; it has to be assessed from the deposit itself.

What affects how quickly it builds

• Burning unseasoned or damp wood
• Smoldering fires with restricted air
• A flue that is too large or runs cold
• A damaged liner or poor draft

That is why a rigid schedule for every home is not accurate. The right interval depends on how much you burn, what you burn, and the condition of the chimney. CSIA and NFPA 211 recommend an annual inspection, and cleaning is done when the inspection says it is needed.

How treatment is assessed

The inspector looks at the deposit’s thickness and type, and at the flue’s condition. Standard sweeping is common for soot and light creosote. Hardened or heavy glazed deposits may need more than one pass or different methods. If the deposit has damaged the flue or the flue has defects, cleaning is not the only step. A camera scan may help, and chimney inspection may be recommended first.

Questions to ask

• What type of deposit is this, and how thick?
• Can it be removed by sweeping, or is something else needed?
• Does the flue show damage from it?
• What changes in my burning habits would reduce buildup?

Our service

See our chimney cleaning page. Related: smoke problems, chimney odor, and Our Work.