The process of closing off a flue is relatively straightforward. Unfortunately, more often than not it is done is a very shoddy way, which simply stores up problems for the future. That was the case for one very unluckily family recently when an incident involving their disused flue hit the headlines. More of that further down…
The main thing to remember is that closing off a flue properly is not difficult, as you’ll see below in my step by step guide
Step One – Get The Chimney Swept
It’s important that any lingering soot or debris is fully removed from a flue before it is closed off. There are a number of reasons. Soot is not only acidic, but it also absorbs moisture. This can lead to horrible black marks penetrating through the chimney breast and leaving an unsightly mess on your plaster, wallpaper and brickwork. Soot also remains highly flammable. There was actually a case in Wigan in 2018 where soot in a closed off flue caused a chimney fire because of heat transfer from some spot lights! So you can now see why it pays to get the flue swept.
Step Two – Choose A Suitable Terminal
This is particularly important if you have an open chimney pot, as they allow not just water, but also wildlife into the property. I’ve lost count of the number of times a homeowner has called me up over a bird which has fallen down a disused chimney, only to there is no way of getting to it other than to break into the chimney breast. Prevention is better than cure, so make sure your flue is adequately protected from unwanted visitors. There’s plenty of options to choose from, such as stainless steel caps to ‘pepperpot’ terracotta inserts, so ask your local sweep.
Step 3 – Decide How It’s Going To Look Inside
There’s a number of options for this. You could have the fireplace removed – remember that if it is a gas appliance then you must ensure this is done by a Gas Safe registered engineer. It is illegal for other persons to tamper with a gas appliance in this way.
Once the fireplace is removed, you could simply replace it with an electric effect fire, or fill in the hole to create a blank chimney breast. I’d always advise an air vent in this case as again it will help stop damp.
If room is at a premium, you could use the fireplace recess for storage, however I would advise that access to the flue is blocked off in some way. The best way is to have it boarded off with suitable materials, but have an access hatch in it if the flue needs to be inspected or swept again in the future.
The key thing to remember in this is that, even if your flue is not in use, it can continue to give you issues as it deteriorates with age. This leads to mortar falling internally (which is why i advise an access hatch if you are keeping the recess open). The only way to counteract this is to have the entire flue taken down altogether. This is expensive, in some cases impossible due to the way they are constructed. It also takes away the option of either you, or a future owner, having a fireplace put back in at some point.
My advice is to keep the flue in situ but have it well vented. Air will need to pass through the system. This will not only help stop damp, but also go some way to eradicating the ‘musty’ smell all old flues have.
Properly done, a closed off flue shouldn’t give you too many future problems. Done badly, it could be quite costly over the long term.
Mr Soot Chimney Sweep is a HETAS Approved Sweep, and member of the Guild of Master Chimney Sweeps, offering a professional and friendly chimney sweep and stove service in Wigan, Stockport, St Helens, Ormskirk, Chorley and surrounding areas. Book Mr Soot online or call 07724 311 992.