zoothorn Posted December 10, 2022 Share Posted December 10, 2022 Hi y'all, my very old folks' sittingroom fireplace, has a 500x500 hole in, with an 80's electric bar/ convector freestanding heater plonked in front to hide it. Old fire area situated back, behind the fireplace, & chinmey going up long since used. If I pull aside the cheapo heater, exposing the big gap, I feel cold air coming down from chimney, plus see exposed wall cavities each side. A recipe for mice, & cold air into their sittingroom. I've temporarily blocked the hole last xmas: 12mm ply covered in foil, well glued to the (marble I think) fireplace surround.. telling them please leave a gap from cheapo leccy fire to it. And to please get builder in to do. Which they haven't done. So I need to do this fill-job properly this xmas for them, with an insulated back, bearing in mind the bar fire just in front: which they rarely use (cost) but just in case they rarely do turn a bar on. Could you advise? Pretty simple I'm sure, but need to be super-sure because of safety/ proximity to this cheapo bar fire. ThankZ Link to comment Share on other sites More sharing options...
zoothorn Posted December 10, 2022 Author Share Posted December 10, 2022 (edited) Simillar to this (fixed) gas fire eg & fireplace, but thankfully I can access behind by pulling aside their leccy fire. If you imagine behind the gas fire here, is a gaping 400x400 hole the the gas fire is hiding. The cream coloured 'front' of fireplace here, marble perhaps too, is what my ply board is attatched to. Edited December 10, 2022 by zoothorn Link to comment Share on other sites More sharing options...
TonyT Posted December 10, 2022 Share Posted December 10, 2022 (edited) You get balloons designed to block up unused chimney google chimney balloon Edited December 10, 2022 by TonyT 1 Link to comment Share on other sites More sharing options...
Radian Posted December 10, 2022 Share Posted December 10, 2022 4 minutes ago, TonyT said: You get balloons designed to block up unused chimney google chimney baloon And also "chimney sheep" Link to comment Share on other sites More sharing options...
zoothorn Posted December 11, 2022 Author Share Posted December 11, 2022 14 hours ago, Radian said: And also "chimney sheep" Chimney sheep? Is this an xmas wind up? Heard of chimney sweeps.. but.. Link to comment Share on other sites More sharing options...
zoothorn Posted December 11, 2022 Author Share Posted December 11, 2022 14 hours ago, TonyT said: You get balloons designed to block up unused chimney google chimney balloon Hi TT, well now I never knew of such a thing. Ok I don't actually know if the chimney has been blocked / closed up though. All I know is there's a 400x400 hole behind the freestanding cheapo leccy fire, & I see the insides of the wall cavities. If I patched up this hole, & what I was thinking was how to do with an insulated panel or something, wouldn't this have the exact same effect as ballooning the chimney, then patching this hole? I mean your suggestion if I just do this, leaves the hole behind the fire still there, & mice get in/ any cavity air gets in too. ThankZ Link to comment Share on other sites More sharing options...
Radian Posted December 11, 2022 Share Posted December 11, 2022 45 minutes ago, zoothorn said: Chimney sheep? Is this an xmas wind up? Heard of chimney sweeps.. but.. https://www.chimneysheep.co.uk/ Link to comment Share on other sites More sharing options...
zoothorn Posted December 11, 2022 Author Share Posted December 11, 2022 @Radian thanks for this. But I'm visiting my elderly folks for 4 days. In order to do this extra-barrier idea (either the balloon or the sheep), I'd first need to measure chimney, buy product, fit.. then crack on with my hole patch job. They live in a village, nothing like either of these will be available in a shop even in a town nearby. If there is a universal-balloon-sized product, then I can buy before & have upon arrival/ do this extra-surity idea first (ideally so, if that is, it's not already blocked with something- this I don't know) then my main barrier . ---- So in meantime I just need help on the main barrier "patch job" to replace my temporary foil-covered ply. It must be 1) insulated, 2) made with the adjacent leccy fire in mind ( safety aspect ). Thanks, Zoot Link to comment Share on other sites More sharing options...
Radian Posted December 11, 2022 Share Posted December 11, 2022 The only insulation product that isn't flammable that springs to mind is vermiculite. You can buy it as a solid board or loose in a sack If you got a 100L sack, that would fill a 0.5 x 0.5 m aperture to a depth of 0.4m for example, and you can pour it in after panelling over the hole. Link to comment Share on other sites More sharing options...
zoothorn Posted December 12, 2022 Author Share Posted December 12, 2022 On 11/12/2022 at 11:55, Radian said: The only insulation product that isn't flammable that springs to mind is vermiculite. You can buy it as a solid board or loose in a sack If you got a 100L sack, that would fill a 0.5 x 0.5 m aperture to a depth of 0.4m for example, and you can pour it in after panelling over the hole. Hi Radian, do you mean pouring in some form of vermiculite chips, from a bag, presumably down the chimney..? Im a bit lost sorry. I was at the stage of simply needing to form a better board/ panel. To cover the vertical 400x400 hole. Ok, if I propose an idea, maybe someone could tell me if A) this is any good, or B) if not, then perhaps advise on an alternative. Ok an idea might be: two large 500x200 tiles, 1/2" thick some form of marble or ceramic. Form my hole shape with 50mm PIR. Glue the tiles to this. Insert into hole, glue the excess 100mm of tile at top to the fireplace marble. And ideally also a lip around edge to glue onto the fireplace on 3 sides. Thanks, Zoot Link to comment Share on other sites More sharing options...
MikeGrahamT21 Posted December 12, 2022 Share Posted December 12, 2022 (edited) https://shop.vitcas.com/vitcas-fireplace-construction-board.html?gclid=CjwKCAiAv9ucBhBXEiwA6N8nYHH31OuU6Kkh_bRx6ATlp7wwSQ81fzygmzTxvQmZEyEfWGpNjLnkoRoC5wEQAvD_BwE Something along these lines is what you need around a fire, doesn't matter if it does or doesn't get used then Or as suggested above, Vermiculite High Density Boards. Edited December 12, 2022 by MikeGrahamT21 Link to comment Share on other sites More sharing options...
Radian Posted December 12, 2022 Share Posted December 12, 2022 The air in the chimney void will probably be at outside temperature. Given the modest volume of the opening I would be looking to fill it with insulating material. Hence loose vermiculite poured in from a gap at the top of whatever panel you close the opening with. Link to comment Share on other sites More sharing options...
zoothorn Posted December 23, 2022 Author Share Posted December 23, 2022 (edited) Hi Chaps, sorry I lost track/ just prepping this job now. Thanks for reading & replies. Alas I can't get onto roof to pour anything down chimney. I think perhaps chimney itself (IE the vertical hole) might be blocked anyway (I can't feel a chimney draught.. seems only cavity draught). So I need to do this: Replace my temporary panel, with a better insulated one. If someone can simply advise on my idea here s follows: just whether this idea is decent enough. It might not be perfect, but I cannot do perfect. I just need it 1) to provide insulation at this gap, 2) to be safe enough. So: I have 75mm PIR to take up. I have adhesive. I have 2x large 10mm marble tiles ( or whatever marble effect modern stuff its made from). Idea: cut PIR to the 400 x 400 hole size. Glue two tiles onto it making a 500 x 500 tile area. Glue it to the front of fireplace. The additional tile area at the sides used as a lip, to fasten onto the existing fireplace front. I use intumescent fireproof silicone at the tile junction, & around perimeter, just to make it 'sealed'/ ie no possible way for the leccy bar fire in front (1" min gap away I ask them to put it, minimum) could ever get its heat to the PIR. Thanks, Zoot Edited December 23, 2022 by zoothorn Link to comment Share on other sites More sharing options...
zoothorn Posted December 23, 2022 Author Share Posted December 23, 2022 (edited) On 12/12/2022 at 16:18, MikeGrahamT21 said: https://shop.vitcas.com/vitcas-fireplace-construction-board.html?gclid=CjwKCAiAv9ucBhBXEiwA6N8nYHH31OuU6Kkh_bRx6ATlp7wwSQ81fzygmzTxvQmZEyEfWGpNjLnkoRoC5wEQAvD_BwE Something along these lines is what you need around a fire, doesn't matter if it does or doesn't get used then Or as suggested above, Vermiculite High Density Boards. Hi Mike, thing is if I buy a sheet of this.. I have most of it unused. I know this stuff I used it behind my stove, because, it gets very hot here. There won't be alot of heat behind this leccy bar fire you see. You could put your hand behind easily enough. They dont emit too much heat behind, & they never use two bars, only one. So I dont need "optimum" material here.. just sufficient material. Could you please take a look at my reply above? One with a green sketch. Thanks, Zoot Edited December 23, 2022 by zoothorn Link to comment Share on other sites More sharing options...
TonyT Posted December 23, 2022 Share Posted December 23, 2022 Would be better fitting the pir to the opening, sealing it up and then fixing the tiles. more effective air tightness that way Link to comment Share on other sites More sharing options...
MikeGrahamT21 Posted December 23, 2022 Share Posted December 23, 2022 A cheaper alternative which will still more than do the job is HardieBacker Board (B&Q/Wickes) and also good for the tiles to stick to too and you can glue some PIR to the back of it. If you make a small frame perhaps out of 3x1 fixed to the back of the cream bit, either with screws or glue, and then screw the backboard to the same frame, intumescent silicone to fill the gap and then your tiles onto the board… if I’ve understood your project right Link to comment Share on other sites More sharing options...
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