When is the best time to get your chimney swept?

As the evenings draw in and the temperature starts to drop, the lighting of wood-burning stoves and fireplaces heralds the beginning of autumn and winter. But just how often should you sweep a chimney?

Getting it swept regularly is an important part of maintaining a good working fire so that it’s safe to use and functions as it should.

We asked experts for their top tips and advice on getting a chimney swept before the cold snap strikes.

How often should you sweep a chimney?

"The independent certification body HETAS encourages having your chimney swept at least twice a year when burning wood or bituminous house coal, and at least once a year when burning smokeless fuels,” explains Sally Phillips, director of Chimney Sheep.

Thomas Goodman at Myjobquote.co.uk agrees: “Chimney sweeping should be done annually, for both open fires and stoves, to minimise the creosote build-up. But it’s worth checking with your stove manufacturer, as sweeping is recommended twice a year for some wood-burning and multi-fuel stoves.”

Can you sweep your own chimney?

Sweeping your chimney isn’t a job you should do yourself. “Chimney sweeping is a messy job, so it’s best carried out by a professional sweep,” advises Goodman.

“Chimney sweeps make sweeping a chimney look easy – but it’s not as easy as it looks,” says Phillips.

“You need a lot of equipment to do it thoroughly, properly, and cleanly. A professional sweep should issue you with a dated certificate confirming when it was swept." 

"If there was ever a chimney fire, you would need to prove that it had been professionally swept, so if you’d done a DIY job you risk invalidating your insurance.”

“Sweeps can also spot any potential problems, such as cracks,” continues Goodman. “So, save yourself time and effort by getting a specialist in to do it for you. Look for a sweep that’s HETAS approved or a member of the Guild of Master Chimney Sweeps, to ensure the job’s done properly.”

Cleaning the chimney of a wood-burning stove

“Sweeping a wood-burning stove isn’t too dissimilar to traditional chimney sweeping,” says Goodman.

“But the rods and brush are far more flexible to negotiate the flue bends and prevent damage to your liner. These are pushed through from the front of your stove.”

How to know when your chimney needs sweeping

There are some tell-tale signs your chimney might need sweeping. “If you notice bits of soot falling out of the chimney, or tar deposits, or a smell of creosote when the fire isn’t in use, it’s probably time to get it swept,” suggests Phillips.

“In the extreme, if it’s very blocked then the fire will not draw properly and you will get smoke coming back into the room. In this situation, put the fire out and don’t use it until you’ve had it swept.”

Cleaning gas fires

If you have a gas fire then get it serviced regularly, advises Phillips. They don’t give off smoke as there’s no solid fuel burning but it’s important to get it checked to ensure the gas fire flue is clear.

“Sooty deposits from a gas fire are a sign that it’s not burning properly, which can cause lethal carbon monoxide poisoning,” says Phillips.

Why you should have a chimney swept regularly

Having a boiler serviced is a job you book in once a year to keep it maintained and in good working order. The same should be done for a chimney. “Keeping on top of maintenance helps to improve air flow so that your fire continues to work safely and effectively,” explains Goodman.

“Over time, your chimney will become blocked with tar, creosote and soot left over from the combustion of wood and coal,” says Phillips. “In addition, it can become blocked with debris from the mortar and general decay of the chimney fabric, along with birds filling it with nesting material.”

If you leave it, soot, debris and creosote will build up, with nowhere to go.

“A blocked chimney is a dangerous thing,” stresses Phillips. “Its function is to draw fumes and smoke from the fire up and out of the home. If it’s clogged so much that it doesn’t draw properly, these fumes will not be vented and will remain in the home.

"If it’s blocked with sticks and debris from nesting animals, there is a risk of these catching fire and causing a chimney fire.”

Draught-proof your chimney

Phillips says that chimneys constantly draw air out of a building, so if you’re not using the fire, you should draught-proof it to prevent the loss of centrally heated air and to reduce cold draughts.

How much does it cost to have a chimney swept?

Costs to have your chimney swept vary but you’ll usually get a fixed price of between £50 and £80, according to Checkatrade. London prices will be a little higher, hovering around £90. The fixed cost accounts for one chimney taking about one hour to sweep. Two chimneys could cost an average of £80 outside of London.

As well as where you live affecting the cost you'll pay to have your chimney swept, there are other factors that can increase the price, as Goodman explains: “Chimneys that haven’t been swept for a while will take longer because of the build-up of creosote and soot, and if they’re unprotected from bird-nesting materials.”

A neat sweep

“We have our chimney swept once a year by a lovely sweep who lives in our village,” says homes writer Amy Cutmore.

“Last year, we paid £50. The job took less than 40 minutes, and our neat sweep left the place spotless."

"She brought covers, which she used around the fireplace, and a vacuum to suck up any soot. But the job is not nearly as messy as you might imagine. She even took us outside to show the brush sticking out of the chimney pot!”

Things to do to help keep your chimney flue clean

"Creosote, soot and tar are all deposits resulting from incomplete combustion,” explains Phillips. To help reduce the amount of creosote in the chimney, be mindful of the wood you are burning.

“Damp wood burns really badly and can cause a lot of creosote accumulation in the chimney,” says Phillips.

“Wood should be seasoned for at least six months. You can test it with a moisture meter but a simple test is just to whack one log against another. If it sounds like a cricket ball hitting a bat, it’s dry enough. If it makes a dull thud, then it needs to be left longer to dry.”

A chimney cowl is a good investment

It’s also a good idea to have a cowl fitted on top of a chimney. Cowls are caps that sit on top of your chimney pot and are designed for different purposes.

You can buy a weathering cowl, such as the Weather cowl with mesh (Ventilationland, £40.25), which will help prevent rain, snow and sleet entering your chimney.

Other cowls are designed to stop birds nesting on top of the chimney, such as the Jackdaw bird guard (Direct Stoves, £53.13).

If down draught is a problem that you’d like to stop, then you can buy cowls designed specifically for this, such as the Junior anti-down draught chimney cowl (Chimney Cowl Products, £59.99).

Some cowls have to connect to the flue liner and therefore they are available with different diameters, so be sure to pick the right size for your flue.