Keep your fireplace chimney clean
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Creosote foam after a chimney fire
In a chimney fire, the creosote build-up ignites and burns within the chimney flue.
Photo courtesy of Jack Pixley.
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Cleaned chimney
A clean chimney won't have a creosote build-up.
How often you need to have your chimney cleaned depends on the moisture content of the wood you burn. If you burn
mostly green (wet) logs, have your chimney cleaned or inspected
every 50 burns. If you see moisture bubbling out the ends of the logs when
they’re burning, the wood is wet. This green wood doesn’t burn cleanly and
sends a lot of unburned particles (smoke) up the chimney, where they build
up as creosote and soot. Dry hardwoods, such as oak and birch, burn hotter
and cleaner. With them, have your chimney cleaned or inspected every
70 burns. A chimney cleaning costs $225 to $400.
Creosote and soot buildup in the chimney flue is dangerous because it can
ignite and cause an uncontrollable chimney fire. A quick way to tell if your
chimney needs cleaning is to run the point of your fireplace poker along the
inside of your chimney liner (photo below). If you find a 1/8-in. or more layer
of buildup (the thickness of a nickel), call a chimney sweep. The chimney
sweep we talked with said he sees 40 to 50 chimney fires a year, and more
than half of the chimneys he services require extra cleaning because the
homeowners wait too long before calling. In extreme cases, the hardened
layer of buildup requires cleaning with special tools or chemicals.
If it’s been a few years since your last chimney cleaning, now’s a good time to
schedule one. The cleaning includes an inspection for soot buildup, obstructions,
cracks in the chimney liner and signs of water damage. Older chimneys often
have gaps between clay liner sections where the mortar has fallen out.
When hiring a chimney sweep, look for someone who’s certified and
insured and will provide an upfront cost estimate. (For a list of certified
chimney sweeps, contact the Chimney Safety Institute of America at csia.org.)
