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

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Doug
 Doug
Member Registered

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 http://www.hse.gov.uk/services/localgovernment/boilers.htm

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)

Studwork

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
Doug

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Topic starter Posted : 1:09 am
race liked
russells
Member Registered

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
Russell

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Posted : 2:27 pm
Admin
Member Admin

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)
Marc

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Posted : 10:09 pm
Admin
Member Admin

Pic as promised

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Posted : 1:18 pm
nicxsystems
Member Registered

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
thanks
Nic

ReplyQuote
Posted : 6:12 pm
nicxsystems
Member Registered

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
thanks
Nic

ReplyQuote
Posted : 7:56 pm
Ed (Senior Member)
(@ed)
Member Registered

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.

Ed

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Posted : 8:18 pm
nicxsystems
Member Registered

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

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Posted : 8:59 pm
Ed (Senior Member)
(@ed)
Member Registered

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!

Ed

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Posted : 9:25 pm
nicxsystems
Member Registered

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 !

Nic

ReplyQuote
Posted : 9:49 pm
Ed (Senior Member)
(@ed)
Member Registered

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.

Ed

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Posted : 8:54 am
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