How Often Should a Chimney Be Swept?

Creosote is the flammable residue that builds up inside the flue as wood burns, and removing it is the main purpose of a chimney sweep. Because buildup rate varies so much from home to home, there is no single "every X months" answer that fits everyone. A household that burns most evenings all winter will need sweeping far more often than one that lights a handful of fires a year. This is exactly why the yearly inspection matters: it measures the actual buildup and tells you whether it has reached the point where a sweep is needed.

A common guideline is that a chimney warrants sweeping once creosote reaches roughly an eighth of an inch, since buildup beyond that raises the risk of a chimney fire. You don't need to measure this yourself, that assessment is part of the annual inspection. You should also arrange a sweep sooner if you notice a strong odor, reduced draft, or dark flaky deposits, all signs that buildup has become significant. When in doubt, an inspection settles whether a sweep is due.