What Is Creosote?
Creosote is a dark, tar-like substance that forms when wood smoke condenses on the cooler interior surfaces of a chimney flue. It is composed of unburned wood particles, gases, and water vapor.
Three Stages of Creosote
Stage 1: A light, flaky soot that is easily brushed away during a standard chimney sweep. Most common in well-maintained chimneys with good draft.
Stage 2: A shiny, tar-like coating that is harder to remove. Forms when airflow is restricted or when unseasoned wood is burned.
Stage 3: A thick, glazed, hardened layer that is extremely difficult to remove and highly flammable. Stage 3 creosote can ignite at temperatures as low as 451 degrees Fahrenheit. Removal often requires chemical treatment or flue liner replacement.
What Causes Excessive Buildup
- Burning unseasoned (wet) wood
- Restricted airflow (closing the damper too far)
- Cool flue temperatures (oversized flues, exterior chimneys)
- Smoldering, low-temperature fires
- Lack of annual cleaning
Prevention Strategies
- Burn only seasoned hardwood with moisture content below 20 percent
- Maintain full airflow during the early stages of a fire
- Keep the flue warm by starting with a hot, brisk fire
- Schedule an annual chimney sweep
- Install an insulated flue liner if your chimney is on an exterior wall
Call Eco Grizzly at (424) 258-9882 for creosote inspection and removal.
