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Removal of Cast Iron Chimney Flue & Fitted Fireplace From inside a BISF House.

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Removal of Cast Iron Flue Pipe & Fireplace From a BISF House by Member Doug.

(Admin note: BISF House member Doug has kindly put together the following excellent post showing the complete process of a cast iron flue removal inside a typical BISF hous.e. In creating this post and taking the time to record the entire process, Doug hopes that he can share his experience with other members and more importantly he hopes that it may be a useful resource for others. Our sincere thanks to Doug for this valuable contribution)

Hello everyone here at BISF House.

I recently removed the cast iron flue and fireplace from a BISF house and thought that I would share it with you all. This post relates to BISF Houses where the fireplace is fitted to wall between the living & dining rooms.

Before starting there are few safety points to bear in mind.

  • You will need a 6-12 inch cast chain cutter. This is a heavy item and will require 2 persons to complete the job.
  • Always wear safety glasses and gloves and if possible, steel toecap shoes just in case.
  • Always wear a high quality dust mask and wherever possible always dampen down any insulation material that may surround the flue with a spray bottle of water. Although not prescribed, we can never rule out the possibility that installers may have used asbestos insulation in some cases. If you suspect the presence of asbestos do not undertake this work until the material has been correctly tested by an approved body.
  • Always wear a disposable worksuit with hood. This can be an extremely dusty job.
  • Never use an angle grinder as sparks can easily ignite insulation or travel under floorboards, causing fire.
  • A strong working platform and extra lighting in the roof would also be a good idea.
  • Don't remove any of the supporting frames yet as it contains the pipe clamps which keeps the flue pipe in place. You can work around the frame without any problem.E
  • Ensure that any and all pipework leading into or out of the fireplace are disconnected or safely capped off away from the work area.
  • All gas pipes should be diconnected by a Gorgi registered plumber.
  • Water pipes if present should also be removed and capped if of no further use.
  • Always turn the gas off at the mains prior to undertaking any work as there may be hidden gas pipes that you are not aware of.

Originally, BISF houses were fitted with open coal fires that heated a small sealed back boiler that was situated behind the main firebox. This was a basic water or oil filled unit that heated radiators in the house. If still present, the box and pipework should be capped and carefully removed.

Admin Update: There have been a number of safety incidents including one fatality where old solid fuel back boilers have exploded due to the recommisioning of old coal fires. Such events are not specific to BISF Houses. Please see

In the 1980's many BISF properties were fitted with Baxi Bermuda gas fires with integrated backboiler. The back boiler was positioned inside the firebox, directly behind the fire itself.
This fire is fairly straightforward to remove once the gas feed has been safely disconnected. The front of the gas fire can pulled forward and carefully separated from the independant back boiler. You may find several mounting screws that need to be removed and possibly a pipe connection but the two parts of the fire and boiler should seperate.

First, completely remove the existing fireplace surround. The surround is usually constructed from large slabs which should be pretty easy to break up using a lump hammer or similar. It would be wise to dismantle the top mantle slab first. One stripped away you should be left with the concrete firebox surround. (Images 1 & 2) and also the boxing from around flue in the front bedroom.  ( Images 3 & 4) Note the flared joint located 2 thirds up in the bedroom. (Image 5)

Firstly remove the fire place surround

Side view of fireplace

First, remove the fire place surround (Images 1 & 2) and also the boxing from around flue in the front bedroom.  ( Images 3 & 4) Note the flared joint located 2 thirds up in the bedroom. (Image 5)

 Starting in the attic the below image shows the cast iron flue tube passing through the ceiling plate as it starts its journey down through the house via the first floor ceiling (Image 6)

The next image shows the flue at the point where it exits the roof toward the chimney. You can see at this point that it is clamped into place by a surrounding bracket. (Image 7)

Loft Support

As I won't be disturbing the top part of the flue, my first cut will be just under this top clamp, The chain cutter is feed around the tube and locked into position then slid up to the first cut. (Image 8)

Pipe Cutter

 The cutter works on a ratchet system which slowly tightens the chain until it cracks the tube, it's quite noisy and a bit scary. Also a note as there was a gas back boiler and fire a liner has been fed through the tube as this needs to be removed first I made 2 cuts. (Image 9)

Cut Pipe

Then using a reciprocating saw through the small gap I cut through the liner then removed the small flue section before removing the liner by pulling down and out from the lounge fireplace. I found this the dirtiest job so be warned lots of soot rust etc. came down with the liner. (Images 10 & 11)

A manageable flue section was cut lower down near the ceiling plate. (Images 12 & 13)

*CAUTION* if you cut off a flue section which is unsupported the top cut section jumps upwards due to the force of the cut, BE PREPARED.

My next cut was in the bedroom tight to the ceiling pic 1 then half way above floor level Pic 2 then at floor level pic 3. You could cut larger sections but I opted to keep small sections. (Images 14, 15 &16)

One more cut in the lounge third of the way from the ceiling the cut section being removed from above. The last section which sits in a plate on top of the fire box you can wriggle until its lose and tilt back to lift out. (Image 17)

Flue Frame

You are now left with the frame which is bolted together in 4 sections then another 4 sections in the bedroom bolted to the downstairs frame. (Images 18 & 19)

There are wood batons nailed in the corner angles to which the plasterboard was nailed too, you can pull the nails out to remove the baton to enable to access the frame bolts. This is straight forward but a fiddly job. The bottom of the frame is cast into the concrete plinth I cut the frame at floor level to enable me to remove it as won't be taking up the concrete plinth just yet. Once all the frame has been removed the concrete fire box can be removed in sections although a little heavy easily removed. (Image 20)


Then making good the ceilings and floors is the last job but as I'm about to undertake a major refurbishment of the lounge the making good will be part of that project. (Image 21)

My local scrap merchant took all the scrap away at no cost to me he even loaded it himself!

Hope this is helpful any questions just ask

Topic starter Posted : 1:09 am
race liked
Member Admin

Hi Danny,
No, you don't have to remove the Cast iron flue if you want to install a wood burner in your home.
I know of several residents who have done so simply by installing an expandable flue liner inside the existing flue for added safety and to prevent any fumes from escaping from the flue joints which may or may not be present through movement.

I hope this answers your question.


Posted : 2:04 am
Ed (Senior Member)
Member Registered

Here is what it looks like now I have taken out the flue, fireplace and wall behind it.

I removed the double doorway lining and the wall below the picture rail and lined the opening with some timber usually used for floorboards. The stanchion I left exposed, filled the holes and painted it black as an ironwork feature, and built a ceiling feature with some LED downlighters to cover the hole in the ceiling where the flue was.

I tiled the hole left by the fireplace and filled the gap in the parquet left by the wall with a strip of wood.

Posted : 9:12 pm
Ed (Senior Member)
Member Registered

Hi all, sorry for the long absence but here are some photos of the finished project.

Downstairs after taking out the flue and fireplace I carefully cut out the wall behind below the picture rail leaving the steel stanchion exposed. I lined the opening with 21 x 147 mm timber (usually used for floorboards) to match the window linings in style. The steel stanchion I left exposed as it's quite small and thought boxing it in would make it unnecessarily large. I filled the holes in it and painted it black as an ironwork feature.

Lastly I made a ceiling canopy/feature with LED downlighters to cover the hole in the ceiling left by the flue.

I'm really pleased by the new layout. I think the front room works a lot better without the fireplace as the sofa can go against the hallway wall.

Posted : 5:49 pm
Member Admin

Hi Ed, I'm sorry to see that your images appear to either not uploaded or gone astray for some reason.

I've searched the entire Media Library behind the scenes but to no avail.

Would you be able to upload them again if you still have them please?

Best regards


Posted : 11:41 pm
Member Admin

It looks like these images are missing too, I sit and scratch my worn head.

Posted : 11:43 pm
Member Registered

Hi Doug 

i live in a BISF house and I’m assuming this is what my chimney breast looks like underneath the brick/concrete. My plan is to remove the chimney breast in my living room only. Do I have to remove the whole flue or can I just get supporting steel beams? If I do have to remove the whole flue can this be done without opening up the wall in my bedroom? 

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Posted : 7:58 am
Member Admin

Hello Vicky, 

Sadly I haven't seen @Doug online for a while but I do hope he pops back in and responds to your reply.

Looking at your photograph, it does appear that you have a B.I.S.F type B floor layout which is a little different to the type A floor plan.

Most notably, the A1 type B Floor Layout have a traditional style brick encased flue that is usually located on the party wall between the two properties and a visible short brick chimney stack protruding from the roof.

The Type A1 A layout doesn't have a brick chimney breast but rather a cast iron flue which is boxed in with a timber frame, leading down to a fireplace and hearth, usually located on the dividing wall between the front and rear of the house. This was the type shown in Dougs flue removal post.

The type A1 A layouts usually have a kitchen and separate dining room to the rear of the house, whereas a type B, may have a kitchen and bathroom here instead, although even this may vary between properties.

Having only worked on the A floor plan layout properties myself, I'm not 100% sure of the internal structure of your chimney or even if it has a cast iron internal pipe at all.  I had always assumed that those properties with traditional brick chimney breasts did not require a cast iron flue. (But that is only an assumption).

It would be great if we could her from anyone with a type B floor layout and traditional chimney breast as they may be able to provide an answer for us both.



Posted : 4:58 pm
Member Registered

Hi Doug. Thanks so much for taking the time to photograph all the stages the putting this up on the site. It's really helpful.
We were about to remove ours, following your instructions when we had the idea of keeping it and installing a wood burner. Would that be fairly easy? Would we keep the flue liner in there or have to take it out ? would the flue stay in place if we removed the concrete block its resting on ? Oh and, probably most importantly, would all this comply with the fire regulations ?

Posted : 9:10 pm
Member Registered

Oh if forgot to say has a Baxi gas fire with back boiler fitted. cheers

Posted : 9:11 pm
Member Registered

I'm about to start similar work on my property.  I've got down to the timber casing but I'm not planning to go any further whilst the gas fire is still plumbed in and working. Once it's removed I'll start this work in the living room this year, and upstairs in 5 or so years when we replace/move the gas boiler. 


My question; is there anything structural to the house with the chimney stack to be wary of or can I make the living room wall flush after removing the flue and stud work?



Posted : 12:22 pm
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