Do I Need a Flue Liner for My Chimney?
It is one of the first questions anyone asks when they start thinking about installing a wood-burning stove: do I need to line my chimney?
There are three main reasons for fitting a flue liner. The first relates directly to health and safety. If you opt for a short run of flue running through a register plate (the plate used to seal the bottom of an open chimney), you are reliant on the quality of brickwork inside your open chimney.
Homes with and without Chimneys
If there are gaps in the brickwork or problems with the pointing, there is a danger that gases, including deadly carbon monoxide, could leak into rooms adjoining the chimney and the loft.
This is less likely in properties built from the mid-1960s onwards as these should have a concrete or clay liner already in place in the chimney.
The second reason for lining your chimney also has a safety element, but relates to the aesthetics of your home, too.
Wood burns at a lower temperature than the coal for which your chimney was probably intended. The gases released when you burn wood are more likely to cool and condense in an open chimney. This can cause build-ups of creosote in your chimney, which can lead to unsightly stains spreading onto the chimney breast inside your rooms. A build-up of creosote also increases the chance of a chimney fire.
It’s worth pointing at that everything we’ve mentioned so far is very much a worst case scenario, but they are probably worth filing under ‘better safe than sorry’.
The third reason for installing a flue liner is to improve the draw. This is the air flow through the flue that encourages your stove to light and to burn. A relatively narrow flue pipe encourages a better draw, which is likely to mean your stove heats up more quickly and burns more efficiently.
It is also important to investigate whether your insurance company requires that a flue liner is fitted. It is probably not worth the risk of losing a pay-out in the case of a chimney fire if your policy says you need one.
So, it’s not compulsory to line your chimney, but it’s probably not a risk that we would be willing to take, and particularly not in older properties. If you decide you don’t need a flue liner we would still recommend:
- Getting a HETAS-registered expert out to inspect your chimney and make sure there is no obvious damage that could lead to problems.
- Getting your chimney swept regularly. This will help to avoid a build-up of creosote.
Gr8FIres 2019-11-05 10:46:07
@ Steve P Hi Steve, Safest bet would be to get a couple of installers out for quotes and to ask how
they would approach the job. They'll be able to take a proper look at everything and advise you
accordingly. Thanks, Gr8Fires
Steve P 2019-10-30 22:20:25
I have an early 90s built hose with external chimney, originally fitted with a gas fire. after
removing the fire we found the chimney is of a square concrete construction, aprox 9", my question
as with many others is whether or not it requires a liner, and due to the size and shape of the
space at the bottom of the flue i cannot fit a regular register plate, any ideas what i can do to
fit a multi fuel stove safely?
Gr8Fires 2019-08-29 20:43:17
@ Phil Lawrey Hi Phil Thanks for the kind words. Gr8Fires
Gr8Fires 2019-08-29 20:41:37
@ George MacKenzie Hi George If it's not stainless steel then you will need to use inhibitor in the
water. Thanks, Gr8Fires
Gr8Fires 2019-07-29 11:24:59
@ Annie Cudmore Hi Annie Thanks for the kind words. With regard to your chimney, you would really
need to get a competent installer to have a look to see if the existing chimney could be reopened
easily and, if so, whether the structure is suitable for use as it is or whether you would to line
it. A twin wall flue would be an option if there are problems with the existing
chimney. Thanks, Gr8Fires
Annie Cudmore 2019-07-07 08:57:56
Hi, love your posts, they are all really helpful! Heres my question.... I live in a stone/slate
Welsh cottage. Currently, there is a blocked up open fireplace on the inside of what was the
original stone wall, now added onto with a modern block extensipn.The internal chimney is still in
place, goes up to the loft, and has not been filled with rubble, but has been capped, and there is
no external chimney outlet on the roof. I really want to put in a 4 or 5kw stove (its a tiny
cottage!). What should I do about the chimney? Thanks! Annie
Gr8Fires 2018-12-05 20:46:53
@ David Preece Hi David The internal liner should be such that any water or creosote can drip right
down the liner and not sit on any ledges. The right way up there would be no
ledges. Thanks, Gr8Fires
DAVID PREECE 2018-12-02 14:39:50
Hi i have just purchased a flexible flue linner but theres no arrow making which way is up for the
air flow how do i find this out please.
Gr8Fires 2018-09-18 14:52:26
@ Vivienne Sutton Hi Vivienne Here are our DEFRA exempt stoves:
Vivienne Sutton 2018-09-12 15:39:17
Good afternoon We have a 6 inch terracotta flue with one bend, will a5 inch flue liner fit. We are
hoping to have a Defra approved stove. Thank you Viv
Gr8Fires 2018-02-04 20:59:53
@ Lauretta Mckinnon Hi Lauretta Not sure what the wrong shape would be - if there's an existing
flue you would expect this to go straight up. The wrong material or wrong diameter would be more
likely. There will definitely be a way around it, but it might entail fitting an entirely new flue
(in place of the existing one or elsewhere) if the information you have received is
correct. Thanks, Gr8Fires
Lauretta Mckinnon 2018-02-02 19:45:59
Hi, a builder told me that l had the wrong shaped flue in my chimney...so can't have a multi fuel
burner....is there a solution to this ...thanks
Gr8Fires 2018-01-29 15:01:11
@ Christine Cammack Hi Christine You will need to smoke test it, but it should be okay for use.
Depending on the diameter, you might wish to line it to help with efficiency. Thanks, Gr8Fires
Christine Cammack 2018-01-27 09:20:04
We have clay liners up our chimney , do we still need flue liners all the way up. Thanks.
Gr8Fires 2017-12-04 11:10:39
@ Roy Saunders Hi Roy Yes, we certainly do. You'll find those here:
https://www.gr8fires.co.uk/flues/twin-wall-flue/complete-twin-wall-kits Thanks, Gr8Fires
Roy Saunders 2017-12-03 09:57:56
I would like to install a multi fuel stove to my external wall do you supply an external flue kit
for this purpose
Gr8Fires 2017-10-30 09:43:30
@ Keith Wixon Hi Keith That would be unusual to have a flue narrower than a flue liner, but if the
chimney was not suitable you would probably have to revert to the instructions for properties
without a chimney. Thanks, Gr8Fires
Keith Wixon 2017-10-26 08:24:34
What if some reason you cannot fit a flueliner down the chimney.
Gr8Fires 2017-08-21 12:13:29
@ Janet Watkinson Hi Janet We're not installers (probably worth getting one round to take a look),
but in general it will depend what it was condemned for. If it failed a flue test, installing a
woodburner with a flue liner should solve the problem. If there is something dangerous relating to
the structure, you might need to address that first. Thanks, Gr8Fires
Janet Watkinson 2017-08-18 10:33:59
Hi My chimney has been condemned as the brickwork is shot. Would I have to have this completely
repaired in order to install a woodburner or could I simply have a flue fitted? Look forward to your