Your fireplace chimney, which is lined with a flue, serves an important
safety function in your home. The flue provides a pathway for potentially
dangerous gases when you light a wood fire in the fireplace, venting them
outside. Your safety is compromised when your chimney’s interior gets dirty
because that prevents the flue from functioning properly.
Burning wood in a fireplace produces many by-products, like unburned
bits of wood, gases, tar fog, minerals, smoke, water vapor and hydrocarbons.
Those materials are hot when they move up through the chimney, and the
flue’s upper areas are cooler. This contrast causes condensation, and over
time a sticky, brown or black material called creosote forms on the flue’s
interior. Creosote is combustible and can cause a chimney fire if the flue is
not cleaned out.
Certain factors allow creosote to build up more rapidly, including the
use of uncured wood in your fireplace, colder than normal temperatures
that make the upper part of the flue very cold, restricting airflow in your
fireplace by using closed glass doors or not opening the damper enough.
Creosote is very visible and takes on several forms. It is always black or
brown, but it can be sticky, drippy, flaky or shiny.
Your chimney can catch on fire from a heavy creosote buildup. Regular
cleaning keeps your fireplace flue safe, especially if you use the fireplace
often. The U. S. Consumer Product Safety Commission recommends
a chimney inspection by a qualified professional at least once a year.
Professional chimney sweeps can assess your flue’s condition and clean it
when needed. Prevent the buildup of creosote between cleanings by using
well-seasoned wood. Never throw trash, paper or cardboard into your