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

bisf house flue and fireplace removal images

Removal of BISF house cast iron flue pipe & fireplace by site member Doug.

(Admin note: Non Standard House member Doug has kindly put together the following excellent post, depicting the complete process of a the flue removal from the inside of a typical BISF house. By 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 all. Our sincere thanks to Doug for this valuable contribution)

Hello everyone.
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 work overall with hood as 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 disconnected by a Corgi registered engineer.
  • Any electrical connections should be removed by a qualified electrician.
  • 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 re-commisioning 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 back boilers. 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 safely disconnected.

Click on Title Tabs Below to View Additional Content

  • Safety
  • Fireplace
  • Bedroom Flue
  • flue Joints
  • Loft Plate
bisf house chimney flue removal

This first step assumes that all gas and electrical connections have already been removed by qualified tradesmen.

Some BISF houses were fitted with original coal fire powered back boilers. If still present, these will also need to be disconnected and removed.

The same goes for owners of Baxi Bermuda gas fires with rear gas fired back boilers.

Please ensure that normal safety procedures are always followed.

Do not start working on any fireplace, back-boiler, or flue, until you are 100% certain it has been fully and safely disconnected.

The information posted here, is for entertainment purposes only and should not be viewed as a definitive guide in any shape or form. We take no responsibility for any loss or damage caused as a direct result of anyone replicating the information posted here. Do so at your own risk. You have been warned.

bisf house chimney flue removal

First, I 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.

I thought It would be wise to dismantle the top mantle slab first. Once stripped away I should be left with the concrete firebox surround and steel frame

bisf house chimney flue removal

Because I actually planned on removing the middle section of the flue that runs up through the bedroom, I also had to remove the hardboard boxing that surrounded the metal flue encasement, from the bedroom.

Some people choose to only remove the section of pipework that is visible in the living room, but if this is done, I am aware that it must be braced and supported to prevent the rest of the pipe from sliding down and causing injury.

bisf house chimney flue removal

A closer look at the first floor joint connection of the flue pipe.

If the lower section is removed, and the upper section left in place, then it must be braced in some way using metal supports bolted to the framework.

bisf house chimney flue removal

Starting in the attic this image shows the cast iron flue ‘tube’ passing through the fixed ceiling/frame support plate as it starts its journey down through the house, via the openings the loft and ground floor ceiling.

  • Roof Support
  • Clamp Cut
  • Sectional
  • Flue Liner
  • Liner removal
bisf house chimney flue removal

This image shows the point where the cast iron flue exits the building through the roof. The grey material is a moisture membrane, that was installed when the original roof covering was replaced.
You can also see that the flue is clamped into place, along with the steel flue support structure, which should always be left in-situ, as it is connected to the roofs framework.

bisf house chimney flue removal

As I won’t be disturbing the upper loft top portion of the flue, my first cut will be just under the top clamp. The chain cutter is fed around the tube and locked into position, then slid upward to the first cut point.

bisf house chimney flue removal

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 worth noting, in my case, there was a flue liner fitted inside the pipe. This is because there used to be a gas fire fitted with a rear gas powered back boiler that once fitted snugly in the old fireplace. The Flue will need to be removed before I can move forward. This is why I made 2 cuts in the flue pipe. The pipe is quite heavy as it’s constructed from cast iron, and therefore easier to manage when cut into manageable pieces.

bisf house chimney flue removal

I managed to position a reciprocating saw through a small gap between the cuts, and was able to cut through the flue liner.
I then removed the middle flue section before going downstairs to pull the liner out of the pipe.

bisf house chimney flue removal

I removed the flue liner by pulling it in a downward and outward motion until the liner came free from the flue, along with a large amount of soot, dust and rust etc. PLEASE BE WARNED THIS IS A VERY DIRTY PART OF THE JOB – DUST SHEETS ARE HIGHLY RECOMMENDED.

  • Caution
  • Bedroom Cut
  • Mid-Cut
  • Low-Cut
  • Lounge Cut
bisf house chimney flue removal

*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 FOR THIS. it is very heavy.

bisf house chimney flue removal

My next cut was in the bedroom, tight to the ceiling, then another cut half way above floor level, then another at floor level.

You could cut larger sections but I opted to cut small sections for safety and handling purposes.

bisf house chimney flue removal

Mid section Cut, allowing for the upper section to be easily maneuvered out of the cage.
This job would be best suited to two persons, but at the time, I was working alone.

bisf house chimney flue removal

Cutting the lower section.
By the way, the cutting tool can be hired from most good hire shops or purchased online.

bisf house chimney flue removal

One more cut in the lounge, a third of the way up from the ceiling.

I removed the cut section from above in the bedroom.

The final section was still sitting inside the coupling plate on top of the fire box, but it was east to wriggled about until it became loose enough to tilt back and lift out.

It’s worth noting that there is also a support plate/box located at floor joist level in between the ground and first floor.

  • Flue Cage
  • Flue Base
  • Back to Bedroom
  • Frame Removed
bisf house chimney flue removal

This is a view of the flue cage, after the flue pipe and the majority of the fireplace slabs have been removed.

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.

bisf house chimney flue removal

A closer view of the flue pipe collar connection to the fireplace.

bisf house chimney flue removal

There are wooden batons nailed in the corner angles to which the plasterboard was nailed to.
The nails can be pulled out using a claw hammer, in order to remove the baton and enable to access the frame bolts. This is a 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 I 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 and although a little heavy, it is easily removed.

bisf house chimney flue removal

The frame can be unbolted in parts and cut in other. It is quite straightforward once the flue is out of the way. Unfortunately I did not take any photographs of that part.

The next job is to make good the ceilings and floors but as I’m about to undertake a major refurbishment of the lounge, the making good will be part of that project and completed in due course.

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

I hope my little project was helpful. If anyone has any questions or comments, just ask away.

All Project Gallery Images

(Admin Note)
We have also included several other members flue removal images below, which may help those wishing to undertake a similar project.


  1. 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?



  2. 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 ?

  3. 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.



  4. 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? 

  5. 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.

  6. 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.

    1. 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


  7. Hi all, do you have to remove a cast iron flue from your bfs house? I really want to install a woodburner and ideally would prefer to just use this flue to save £££.

    I’d appreciate any feedback.

    Thank you

    1. 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.


  8. I take it the flue is supported by both the iron frame and the concrete fire box?

    We are thinking of having a double sided hole in the wall fire fitted (kitchen and living room), and using the existing flue, but I suppose this will involve removing this support, and devising a new way to take the weight!

    Were these fireplaces designed for gas only as there are so many pipes actually in the fire box?


  9. Hi all, we have just taken the steel cage out in the living room. Ed, your images were very helpful. See pics for the process!

    The steel wore 3/4 blades out and I still have the base to smash out to make the floor level. Anyone know how deep the steel cage feet are embedded? I have cut them off just above floor level for now.

    We are aiming to keep the flue and install a woodburner. Anyone with any advice on this would be greatly appreciated. Will we need a new sleeve inside the flue for this purpose?

    Also, we discovered loads of redundant pipe work within the steel cage that was a hangover from the old heating system. The boiler is now in the loft and there are two functioning HW pipes also running down the flue cage, we need to put these into the wall which is a bit of a pain.

  10. Hi all,

    I’ve started removing our flue the other day. I couldn’t find a chain cutter locally large enough to hire, so I have been using an angle grinder instead and done it in a slightly different way from Doug.

    First of all I cut the flue off in in the loft as close to the roof clamp as possible and then again about half way down to the loft floor, to keep the size of the pieces manageable. As I didn’t have a special saw to cut through the flexible flue liner inside, I used the angle grinder to cut this section of flue in half length ways. Once so exposed the liner was very easy to cut with the angle grinder. Then I cut the next section off the loft floor. The pipe is big enough that when you cut fully through it doesn’t risk toppling over and injuring you, it just sits on the part below, which is an advantage of the angle grinder over a chain cutter. Also the flexible flue liner helps keep it in place – I found I had to lift the cut section up off the flue liner and then cut the liner.

    I found it was better to dismantle the steel frame around the flue in the bedroom first so it was easier to cut it. Even so it wasn’t possible to get the angle right behind it in the corner between the wall and cupboard so there was a bit at the back of the flue that remained uncut, but if you free the flue first by taking off the clamps it breaks off fairly easily if you push against it.

    I found the flue liner was too tight to pull out in one piece as it’s quite a snug fit and the inside of the cast iron flue is very rough.

    I haven’t yet got down to floor level in the bedroom. The next step will be to repeat the process in the living room. I’m still deciding whether just to gain the extra space in the bedroom where the flue has come out, or to build another cupboard in its place for extra storage up against the end of the existing built-in cupboards.


    1. Hi Ed, glad to hear that your flue removal is going well. I’m surprised to hear that you’re getting good results with an angle grinder as I tried this once using a standard steel cutting blade, but the blades wore down so quickly. I have since found a much better multi purpose steel rather than carbon type blade that lasts longer and cuts almost anything. What type of blade have you been using and what size angle grinder?
      Are you going to remove the chimney casing too or are you going to block it off?

      It’s a hefty old pipe too and as you say, cutting and removing it in sections is vital to prevent injury and having removed a few I was surprised to see that the cast iron itself was still in excellent condition, despite having read several reports stating that the pipe would probably have started to corrode by now. What condition was your flue in?

      I look forward to seeing any photos that you might have taken too Ed, please keep us updated.


      1. Hi Marc, it’s all out now together with the frame, fireplace and firebox so the only things left are the concrete slab that the firebox sat on (that I’ll have to break up before making good the floor) and the last bit of flue that goes through the roof (this and the chimney box thing round it will go when the roof covering is eventually replaced).

        I hadn’t actually used an angle grinder before so I’m not sure what to compare it with, but the flue cut more easily than I was expecting. I used a Norton flat metal cutting disk 115 x 2.5 x 22.2 mm ( and a 110V ‘pro’ grade angle grinder that I borrowed from my dad, so perhaps it cut better than a DIY angle grinder. He advised to use the 2.5 or 3mm disks rather than the thinner ones which can shatter.

        The steel frame around the flue was actually much tougher to cut and wore out the disks much more quickly than the flue itself even though there was a lot less to cut through. I had to cut it off at the base where it is cast into the concrete slab and also in a few other places where either the nuts had rusted or it wasn’t possible to get a spanner in to loosen them.

        The outside of the flue was in fine condition but there was a fair bit of rust on the inside. I’d say about a cup full or two of rust fell out of each roughly 600mm flue section when I dumped it outside.

        When I dismantled the fireplace I found a scrap of the Bristol Evening Post that looked as though it had been used to fill a gap, that contained a report of a meeting of the Imperial Tobacco Company on 21 March 1950 so I guess that can be used to date the house. It’s a bit later than I was expecting as the woman who sold the house said her father had lived here for 62 years till his death in mid 2011.

        I also found a capped off lead pipe behind the fireplace which looks like a gas pipe, so perhaps the original heating system was gas rather than coal?

        I’ll post some photos later, I also have some of the bathroom now it’s finished.


      2. Most of the steel frame round the flue removed. As you can see I had to cut one of the cross pieces with the angle grinder as I couldn’t get to the bolt from the cupboard side. I’ve taken the flue out down to the collar and cut the first cut below the collar. I hadn’t taken account of the fact that the collar section is much heavier so you should really cut this out in a shorter piece!

      3. More cut out, you can see the flue liner as well. It’s a bit unusual because it has rockwool type insulation round it and then a plastic sleeve so it was too snug to pull out in one go like Doug did.

      4. Fireplace taken out. Does anyone know what the hole to the left was for? It’s open to the outside as I can feel the air come through it. Was it some sort of drain or for ventilation?

        1. Everything is out now. I had expected the concrete platform to be continuous with the sub floor and I’d just be able to lower it a bit, but it was actually separately cast on top of the sub floor. So taking it out made more of a hole than I’d have liked which will need filling with concrete (I was hoping to just fill with levelling compound)

        1. I’ve also taken out the wall between the dining room and living room after taking out the flue and fireplace. I’ve taken it out up to the level of the top of the former doorway between the two rooms.

          I have tiled the hole in the floor left by the fireplace as I didn’t think I’d ever be able to match the parquet. I was surprised that the stanchion is made of two angle pieces of steel welded together to make a box section as I was expecting a C-shaped steel like those in the external walls. It is also smaller than I was expecting. Instead of boxing it in and making it larger, I have filled the holes in it and painted it black to make it stand out less. Just needs some finishing off.

  11. We have just had our back boiler removed and I’m planning on taking out the flue, starting in the loft and bedroom. I have noticed though that it doesn’t seem to be made out of cast iron but looks like steel to me. I used a hacksaw to cut into it as a test. Cast iron wouldn’t do that.

    Obviously cast iron and steel would be removed in different ways. Steel can be cut more easily than cast iron but can’t be broken/smashed. Were different types of flues used in BISF houses or is this just a case of mistaken identity?




  12. Hi Dave & Nic
    Glad you decided to take the plunge, it will be well worth the effort in the end. :0)
    Which method did you use to break up the flue?
    Once started it’s pretty much plain sailing although it does take a fair bit of hard graft. Don’t forget you can still install a new gas fire if you ever feel the need as there are many flueless systems available that don’t require a flue, although you do need to create a new air gap, but that’s another story.
    Have you removed the chimney cowl from the top of the roof covering otherwise known as the chimney pot on a traditional house?
    Keep us updated and well done with your project

  13. Hi

    I took out my whole flue yesterday which in all honesty was unplanned as I only intended to take out the ground floor and first floor sections and leave the attic section. This article was really useful.

    Had our back boiler removed which allowed us the opportunity to open up the living room more and get rid of the fireplace.

    I am about to start a refurb/ decoration of our lounge. Bisf houses are brilliant even as a beginner DIY’er I have enjoyed pulling down walls and re configuring parts of the house. Will upload photos of the things we have done soon .

    Thanks for everyone else posting articles like this one which have helped me so much

    Dave and Nic

  14. It’s out!!!!! went with the sledgehammer wasn’t as bad as I thought thanks everyone. Trying to remove the framework now any tips? It seems to be held in place just above the living room ceiling and won’t come free?

  15. A quick Google search for industrial chain pipe cutter hire list Brandonhire who have a 19″ cutter but if I am honest I cannot recall the diameter of the pipe.
    In my case I also used a large angle grinder with a special high performance blade that cuts wood, metal, stone etc that was ridged and made of steel rather than normal grinding blades that wear down very quickly when faced with thick cast iron.

  16. Hello Dan
    I have to go with Grangey on that too, albeit not the safest way of removal.
    I used a sledge hammer to remove mine and it was certainly a chore and ear defenders and goggles are a must. It breaks into segments but once it has started to crack it was much easier. It’s getting the first crack in the cast iron that’s the hardest part.
    It’s a bit like smashing up a large cast iron bath only much thicker. Just make if your working in the loft that you have some floor covering or temporary boards in place to prevent large pieces falling through the ceiling board. If working in the bedroom or living room try to cover any windows with tarpaulin to prevent any flying bits from hitting the glass.
    Also make sure you wear a mask and disposable boiler suit if you have to remove any insulation from around the pipe as there is some debate that it may or may not contain asbestos fibres. I wrapped mine with cling film to help keep the fibres in place and also used a water spray bottle to keep them damp and prevent fibres from flying round.
    It is much safer to use a pipe cutter though and due to safety it is the only method that we can recommend. It makes the sections far easier to handle with less likelihood of large pieces dropping down.
    When working from the living room as I did, once the lower section is cracked, you can thin chip away fairly easily until the lower section loosens up and it can sometimes be pulled out in one piece. The upper section should remain in place due to clamps that hold it secure and one is visible in the loft but you should not always rely on these being secure and you should check they are tight before you start.
    The worse case scenario is that once the lower pipe has been smashed. the upper section could drop down if not held securely and believe me it is heavy.
    Make sure that you have a clear working area and are able to move away quickly if you think it may drop.
    Once again though I must stress that using an industrial pipe cutter which can be hired from certain hire shops or drainage companies is the only method we can endorse. We take no liability for any of the suggestions given as they are only personal views.
    At what stage are you at now, have you stripped back the fireplace and boxing?

  17. Trust me, it may be somewhat messier, but I found using a sledgehammer far quicker. I too couldnt find pipe cutters big enough so also tried a disk cutter, it takes ages. Give it some very hard smacks from the top down and once it starts cracking its easy enough

  18. Hi I’m in the process of removing my flue but I carnt find anyone with a pipe cutter larger then 6″. And would love to no where you hired yours thanks

  19. Hi Doug,
    Thank you for uploading all of this information , it is most helpful.
    I have lived in a BISF house in Chigwell in Essex for 20 years. Finally we have made the decision to remove the Flue from the front room. I do not however really want to take it out from the roof as this would mean disruption in our bedroom which was recently decorated.
    Is it possible to just take the Flue and surrounding cage out from the front room only? We have it all exposed now, and need some guidance? Should we cut off and then weld a plate to secure the flue from dropping down , or is there other ways of doing this? Your help and ideas would be most apreciated.
    Kind thanks

    1. Hi Russell
      I’m sure Doug will be along soon to reply to your question but in the mean time I will just add a little if I may.
      I have undertaken both types of removal, ie total flue and half flue as you describe.
      The cast iron flue itself comes in 3 sections but I have also known one property that had just two sections but this is very rare.
      The lower half that goes from the ceiling to the fireplace is the easiest part to remove leaving the center section still encased inside the housing that runs down through the front bedroom. This is held in place with steel “strap”brackets and support frame. You must ensure the straps are still tight. From recollection one bracket is located in the floor joist / roof area of the living room ceiling. The problem that I found was that housing frame sits slightly proud of the ceiling. I welded in a steel base plate for safety which protruded even more so.
      As a result of this and really not wanting to remove the middle section due to just having the bedroom plastered, I built a shallow stud frame on the ceiling and a shallow chimney breast as a feature rather than just having a flat wall which I then plasterboarded. Photo to follow.
      Obviously, making the remaining flue secure is the priority here but if your flue is of the standard 3 section design, I think you may face the same issue. The are chain style manual cutters available to make cutting of the flue easy but as the middle section is hidden from view, tools like this are useless. Angle grinding is another option and you will find some blades are better than others when trying to cut this thick steel. I used a multi purpose blade that cost around £15 to cut some of the protruding iron away but it was hard work.

      I hope this helps a little and glad you got my e-mail :0)

    2. Hi Doug and Marc,
      I too wish to remove my entire fire place, chimney and boxing in. The only thing that bothers me is the thought of leaving the last bit sticking up out of the roof supported only by the top clamp, is it not a bit top heavy? and what have you done to prevent rain coming straight down into the loft?
      I look forward to any advice

      1. Hi Nic, maybe yours is taller than mine or I have just underestimated it. Here is a photo below. Mine is enclosed by a galvanised steel chimney box and you can see the gas boiler flue and cowl sticking out at the top. I’m a bit surprised yours doesn’t have one as it seems pretty essential! Mine was leaking a bit where the flue comes out at the top of the chimney box until I had the mortar replaced (the little mound around it) but that as a leak down the *outside* of the flue pipe.

        I guess you would either have a choice of taking out the whole pipe and making good the hole or leaving the top part in and putting a cap or cowl on top. I’m finding it a bit difficult to imagine how it is at the moment!


        1. Thanks Ed,

          Unfortunately I don’t have a cowl on top of mine, I do have an extra outer pipe with a flat plate on the bottom which sits on top of my metal tile effect roof sheeting, but when it rains hard some water does come straight down inside and outside of the main flu pipe and stops a bit past the clamp that is part of the roof structure.

          I would say about 2 foot would be left sticking up from that clamp, out through the roof with no upper support as i no longer have a timber box on the outside that would have originally sat on top of the old asbestos corrugated roof sheeting and we do get a lot of strong wind here near the top of Portsdown hill overlooking Portsmouth harbour !

          cheers Nic

          1. Hi again Ed,

            you have another variation of box around your flu and it is cool, mine is the same as the one on the left in this photo taken from the gallery bisf diversity, my biggest problem is that i cannot easily get up on top of the roof as the soffit is large and the ground around the house is very uneven nor is there enough room for a tower so scaffolding would need to be erected to gain access for an hour to put a plate over the hole, which seems excessive if i can find another way around it !


          2. Hi Nic, I’ve never seen one like that with a bare flue pipe! Round here they all have some sort of box over the flue, either like the one I have which I guess is original or a replacement like the one next door. On a few reroofed houses the original box has been re-used.

            My dad actually did the chimney repairs, but unfortunately I was at work when he did it, but he said it was not difficult to get up there. I know he used an ordinary ladder and a roof ladder. However we do have a concrete terrace at the back to put the ladder on. I’m guessing he put the top of the ladder on the eaves just under the gutter.

            I can’t think of a way of doing the work from the inside, but I don’t have much experience of that so hopefully someone else can help.

            BTW those terraced BISF houses look very unusual to me and the bathroom window seems to be in a different position from usual too.


    3. reposted to correct timeline?
      Hi Doug and Marc,
      I too wish to remove my entire fire place, chimney and boxing in. The only thing that bothers me is the thought of leaving the last bit sticking up out of the roof supported only by the top clamp, is it not a bit top heavy? and what have you done to prevent rain coming straight down into the loft?
      I look forward to any advice

      1. Hi Nic,

        I haven’t removed mine and still haven’t decided whether I will or not, still debating in my mind whether the extra space and potential for simpler reroofing is worth the work, loss of fireplace focal point flue for a new boiler or woodburner etc and useful route for running various pipes and cables down the centre of the house! However, from being up in the loft I know that the section that is left in Doug’s photo is pretty short so I wouldn’t worry about it. Also, I would be surprised if it is open at the top otherwise rain would be come down already. There will almost certainly be some sort of cowl or whatever it is called on top to prevent rain coming in. In my case it’s the cowl on top of the flueliner for the back boiler, which is inside the larger steel or cast iron flue pipe. If you look up at the chimney box outside you should see some sort of cowl.


  20. Thanks Doug for your advice, it’s a pity but kind of what I was expecting.

    The engineer who checked it when we bought the house said we should keep it as he said they are very reliable and inexpensive to maintain. Hopefully having insulated the loft and started to insulate the walls our gas bills will be further reduced this winter!

  21. Hi ED
    They do operate independently of each other but are classed as 1 unit and should not be separated occasionally we disconnect the back boiler and decommission it leaving the appliance in place with the fire usable but there are regulations covering this. So you will be unable to reduce the amount it sticks out but might be able to shave some off the sides.
    However you could remove the surrounding tiles and mantle to replace with different tiles or any non-combustible material providing the finish surface is the same thickness as existing so the fire sits against it
    In fact I have seen it done with a pre made mantle surround and marble effect infill from B & Qs. The gas fire casing is easily removed to expose the surround

  22. Here are some photos, you can see how far into the room the gas fire sticks out. I wanted to take it out and everything in front of the bricks you can see where I’ve taken the side panel off, so that the mantelpiece is the front-most part of it to give a more normal look.

    To clarify, I wanted to know if the boiler would work without any type of fire in front of it, as they appear to operate independently or are the two things actually one unit?

  23. Hi Ed
    You are correct in thinking that the fire and boiler are connected and you can’t remove the fire to replace with another type. Baxi used to do a selection of different forefronts but were hugely expensive. Even if you went down the new back boiler route the flue liner will need to be replaced at a cost and they only have an electric fire on front although there is talk of a gas one in the pipeline. Most boilers fitted into BISF houses are installed into the old cylinder cupboard and flue through the roof, I’ve fitted them into kitchens and also in the old side shed

  24. Hi Doug, we do indeed have a Baxi back boiler for the hot water and central heating, model Bermuda SL3. I was thinking of replacing it either with a combi boiler elsewhere (problem is nowhere obvious to put it) or a modern Baxi Bermuda condensing back boiler in the same place. However, after using relatively little gas last winter I shelved that idea as I thought it would take a long time to recoup the money through increased boiler efficiency.

    I was hoping to be able to remove the gas fire unit and fireplace and replace them with a more stylish fire surround/non operational fireplace and leave the back boiler as it is. I suspect though that the fire and boiler might have to be together to work.

    The fireplace is large and takes up quite a bit of room but I can live with that, but the way the gas fire has been stuck on the front sticking out even further into the room looks ugly I think.

  25. Hi Ed
    As you say that the flue is in use I’m Guessing you have a back boiler fitted Baxi? if this is the case the gas fire is part of the boiler and you have a very limited and expensive choice of fire fronts, If still available. As for the tiled surround you can do what you like providing you keep the existing dimensions e.g. Depth /size of opening. But don’t forget that you would need to consult a Gas Safe engineer before you start any work when a open flue gas boiler / fire are concerned due to ventilation requirements. if you could post a picture should be able to give you some advice.

  26. Fascinating post Doug even though I have no plans to remove mine, which is in use by the boiler. I am looking into whether it’s possible to remove the ugly mismatched pink tile fireplace and gas fire that have been stuck onto the front of the firebox.

  27. Hi Trish
    No real problems as such I found cutting and removing the tube quite simple and took about half a day. The frame surrounding it is a little tricky as some of the nuts and bolts on one side joining the frame together are difficult to access due to the stud wall placed up against it, I had taken pictures of this but sadly I had a corrupted memory card so unable to retrieve them.
    Have uploaded a couple more the first one is in the bedroom with tube removed but with the clamp and frame in stiu

    The second is the tube in stiu you can clearly see the wooden batons that sit in the angle frames which are nailed in place through a hole in the steel these need to be removed to access the frame bolts,The right hand one is tricky to remove as the plaster board is nailed to it

    But a competent DIY’er should have no trouble. If you require any further information let me know

  28. Fantastic post Doug, thank you for sharing this with everyone.

    I have been dying to get my old flue and fireplace removed but hadn’t a clue how to do it and hubby kept saying it’s too difficult! Lol You’ve just proved him wrong hahaha

    It does look pretty easy for the average diy’er did you face any problems or obstacles?