Sweep-frequency advice usually comes as a slogan, “once a year!”, which is close, but the real standard is smarter and can save you money: measure, then clean when measurement says so.
The actual standard
The CSIA guidance: sweep when creosote reaches 1/8 inch, sooner if it’s glazing, and inspect annually regardless. The annual inspection is the measuring event; the sweep is the response when the measurement crosses the line. Some years you’ll need both, some years the inspection alone.
Translating to real life
What accelerates buildup (and moves your interval)
Creosote is condensed, unburned smoke, so anything that makes smokier or cooler fires makes more of it: unseasoned wood (the big one, wet wood can double deposition), smoldering low-air burns, an oversized flue that lets exhaust cool and condense, and an exterior chimney that runs cold. Burn dry hardwood, hot and bright, and you’re manufacturing less of the problem, more in our creosote-prevention guide.