Guide
How often should a chimney be swept?
Updated
The short answer
A chimney in regular use should be swept at least once a year, ideally before the fire season starts in autumn. If you burn wood or coal most days through the winter, twice a year is commonly recommended: once before the season and once after it. A fire that's hardly used still needs a check before you light it, in case of nests or debris.
It depends on what you burn
Different fuels leave different amounts of soot and tar in the flue. As a general guide:
- Wood: the most tar, especially if it isn't fully dry. Sweep at least once a year, and more often if it's your main heat
- Coal: heavy soot. Twice a year if the fire is lit most days
- Smokeless fuel: cleaner, but still at least once a year
- Oil or gas: these appliances have their own servicing schedules; ask your service engineer about the flue
It depends on how often you use it
A stove or range that runs every day from October to April does far more work than an open fire lit at weekends. If the fire is your main heat, plan for a sweep before the winter and think about a second one in spring.
Fires you hardly use still need checking
A chimney that hasn't been used in a while can still be blocked: birds nest in them in spring, and debris falls down over time. Holiday homes and rooms that are only used at Christmas are the usual cases. Have it checked before you light it.
Signs it needs doing sooner
Smoke coming back into the room, a fire that won't draw, a soot smell in damp weather or black flakes in the grate all mean the chimney needs attention now, whatever the calendar says.
Questions
When is the best time of year to sweep a chimney?
Late summer or early autumn, before the first fire of the winter. A second sweep in spring suits fires that are used most days.
Does a stove need sweeping if it burns smokeless fuel?
Yes. Smokeless fuel is cleaner, but it still leaves deposits in the flue, so at least once a year is still the guide.