How often should you get your chimney swept?

If you have a wood burner, multi fuel stove or open fire, the chimney above it needs regular sweeping. Every fire leaves soot and tar on the inside of the flue, and over a winter that build up narrows the flue, stops smoke and fumes escaping properly, and can catch fire. A clean flue is also one of the main defences against carbon monoxide, the gas you cannot see or smell.

This guide covers how often to sweep for each fuel, when to book, how to choose a sweep, what a sweep certificate is for, and the carbon monoxide alarm rules for homeowners, landlords and tenants.

How often to sweep your chimney

How often depends mainly on what you burn, because some fuels leave far more soot and tar than others. HETAS, the government recognised body for solid fuel appliances and sweeps, recommends:

• Wood: at least twice a year
• Bituminous house coal: at least twice a year
• Smokeless fuel: at least once a year

Some fire services set a tighter interval for wood. Staffordshire Fire and Rescue Service advises sweeping quarterly while a wood burner is in use. If you light the stove most evenings from October to March, two sweeps is the minimum and three or four is sensible. If you light it a handful of times at Christmas, once a year is usually enough. Your stove manufacturer's instructions may also set an interval, and that should be followed.

Gas and oil flues

Gas fires and gas boilers do not burn solid fuel, but their flues still need checking. That is part of the yearly service by a Gas Safe registered engineer, covered in our guide on how much a boiler service costs. An old chimney that once served an open fire and now serves a gas fire should be swept before the gas fire is fitted.

Signs your chimney needs sweeping sooner

• Smoke drifting into the room instead of going up the flue
• The fire is harder to light or keep going
• A strong smell of soot or tar, especially in warm or damp weather
• Black, flaky deposits or crumbs of tar falling into the grate
• Birds nesting in or around the chimney pot in spring
• The stove glass blackens much faster than it used to

When to book a sweep

HETAS says the best time is just before the start of the heating season, and also after the appliance has been left unused for a long time. If you sweep twice a year, the second sweep should come after the peak of winter. In practice that means booking in late summer or early autumn, before sweeps' diaries fill up in October and November.

The timing matters because chimney fires peak in the coldest months. HETAS reported in September 2026 that there were 1,665 chimney fires in England between April 2025 and March 2026, down 18 percent on the year before, and that 42 percent of chimney fires happen between January and March, when stoves are lit most often and tar has had months to build up.

How to choose a chimney sweep

Anyone can call themselves a chimney sweep, so it is worth checking. Look for a sweep registered with one of the recognised bodies:

• HETAS, which runs the approved chimney sweep scheme
• The National Association of Chimney Sweeps
• The Guild of Master Chimney Sweeps
• APICS, the Association of Professional Independent Chimney Sweeps

HETAS advises asking to see the sweep's identity card before any work starts. A good sweep will put down dust sheets, sweep the flue with brushes and a vacuum, check that the flue is clear all the way to the top (often with a smoke test), and tell you about anything that needs attention, such as a damaged pot, a missing cowl or a liner in poor condition. A vacuum on its own is not a substitute for a proper sweep.

Ask for a fixed price per flue before booking, and ask whether a smoke test, nest removal or a camera inspection is included or extra. Our guide on how to check a tradesperson is genuine covers the wider checks, such as a full address and public liability insurance.

What a sweep certificate is for

After the sweep, ask for a certificate. It records the date, the address, which flue was swept and anything the sweep noticed. It is useful for three reasons: some home insurers expect regular sweeping where a stove or open fire is used, and the certificate is your proof if you claim for a chimney fire; a stove installer or Gas Safe engineer may ask for it; and buyers' surveyors often ask about chimneys when you sell. Keep every certificate with your insurance papers.

Burn the right fuel

Wet wood is the biggest cause of tar in a flue. Freshly cut logs hold a lot of water, and burning them produces more smoke, more tar and less heat. Since 1 May 2021, wood sold in England in volumes under 2 cubic metres must be certified as Ready to Burn, which means a moisture content of 20 percent or less, according to government guidance. Larger loads can be sold wet but must come with advice on drying them.

• Buy Ready to Burn wood, or season your own logs for at least a year and check them with a moisture meter
• Never burn painted or treated wood, pallets, packaging or household rubbish
• Only burn fuels approved for your appliance, and if you live in a smoke control area, check that both your stove and fuel are allowed there

Carbon monoxide alarms: what you need

Carbon monoxide is a poisonous gas produced when fuel does not burn fully, for example when a flue is blocked or an appliance is faulty. You cannot see, smell or taste it. The NHS lists headaches, dizziness, feeling or being sick, tiredness and confusion, and shortness of breath as symptoms, which can easily be mistaken for flu. A clue is that symptoms ease when you leave the house.

An alarm is the only reliable warning. Fit one in every room with a stove, open fire, boiler or other fuel burning appliance, choose one marked BS EN 50291, follow the maker's siting instructions and press the test button every month. Most alarms have a sealed battery that lasts the life of the alarm, with a date on the back for when to replace it.

The rules for landlords in England

Under the Smoke and Carbon Monoxide Alarm (Amendment) Regulations 2022, in force since 1 October 2022, private and social landlords in England must:

• Fit a carbon monoxide alarm in every room used as living accommodation that has a fixed combustion appliance, such as a boiler, gas fire or wood burner. Gas cookers are excluded.
• Fit at least one smoke alarm on every storey with a room used as living accommodation.
• Repair or replace an alarm once told it is faulty.

Councils enforce the rules and can fine a landlord who ignores a remedial notice up to £5,000. Landlords with gas appliances also need a yearly gas safety check, explained in our guide to gas safety certificates.

New stoves and boilers, and Scotland

In England, Approved Document J of the building regulations requires a carbon monoxide alarm whenever a new or replacement fixed combustion appliance is installed, other than a gas cooker, so an installer fitting a stove or boiler should fit one too.

In Scotland, the rules cover every home, not just rented ones. Since 1 February 2022, the tolerable standard has required a carbon monoxide alarm wherever there is a fuel burning appliance or flue, apart from appliances used only for cooking. Wales and Northern Ireland have their own rules, so check locally if you live there.

What to do in an emergency

If you think the chimney is on fire

Hertfordshire Fire and Rescue Service advises: get out, stay out and call 999. If it is safe to do so, close the air vents or flue damper on the stove first to starve the fire of air. Do not pour water onto a stove or fire. Signs include a roaring noise, sparks or flames from the top of the chimney, and smoke or a burning smell in other rooms or the loft. After a chimney fire, do not light the appliance again until the chimney has been swept and inspected.

If a carbon monoxide alarm sounds

1. Open doors and windows and turn off the appliance if you can.
2. Get everyone, including pets, out into fresh air.
3. If you have gas, call the National Gas Emergency Service on 0800 111 999.
4. If anyone feels unwell, call NHS 111, or 999 if they are struggling to breathe, confused or unconscious.
5. Do not use the appliance again until it has been checked by a Gas Safe engineer or a registered sweep or stove installer.

Find a local chimney sweep

If your chimney is due a sweep, post your job free and hear back from a local chimney sweep. Say what you burn, how often you use it and when it was last swept. You pay the sweep directly, and there is nothing to pay online.

Or browse local businesses: chimney sweeps in Birmingham, chimney sweeps in Coventry, chimney sweeps in Solihull, chimney sweeps in Walsall, chimney sweeps in Worcester or chimney sweeps in Stoke-on-Trent. If a storm has damaged your chimney pot or flashing, see what to do if a storm damages your roof, or browse all our home advice.