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Post by g20wey on Mar 9, 2017 13:59:02 GMT
Hi All,
New to this build and having now ordered all my materials im trying to start construction on the base.
I have purchased a 50mm calcium silicate base and planning on putting 25mm firebricks onto this. From some videos etc I have seen some people add a 25mm level of refractory cement in between the board and the fire brick.
My question is this necessary as some people build straight onto the calcium board.
I welcome your thoughts?
Thanks, Matt
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Post by moonhead on Mar 9, 2017 17:25:55 GMT
Hi Matt and welcome to the forum. Answer to your question is no. 50mm of cal sil board is plenty of under floor insulation. It will also give you a good surface to lay your bricks onto. But it does need to be kept dry. It will absorb water which does it no good at all. I wrapped mine in a good quality tin foil and only used a thin screed of the cement to lay onto. If you want additional insulation keep it under the board. Good luck with your build Rick
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Post by g20wey on Mar 13, 2017 8:36:22 GMT
Hi Matt and welcome to the forum. Answer to your question is no. 50mm of cal sil board is plenty of under floor insulation. It will also give you a good surface to lay your bricks onto. But it does need to be kept dry. It will absorb water which does it no good at all. I wrapped mine in a good quality tin foil and only used a thin screed of the cement to lay onto. If you want additional insulation keep it under the board. Good luck with your build Rick Thanks Moonhead,
Yeah I was planning on covering with foil just didn't know if I needed a layer of refractory mortar then once dry lay the fire bricks on top of this with some fire cement. My worry is that if I use the refractory mortar it will not dry/cure without heat. The Melbourne Fire company, whom I've been following the instructions from use an activator in this refractory, I assume to speed up the curing without the heat.
I would rather just lay the firebricks with a little fire cement if possible but then have read that some people just lay these dry on sand but I suppose I've not noticed if they were using calcium silicate tbh.
Any other help is appreciated.
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Post by moonhead on Mar 16, 2017 7:59:25 GMT
Matt , I laid my base onto a thin screed of mortar, a 1,1,1 mix of fire clay, sand and cement, but a thin layer of fire cement would be OK but this is only useable at a max thickness of 5mm. I've had a look at a video on the Melbourne FC web site and they are covering the board with what looks like a refractory 'heat base'. I think this is to add thermal mass to the base as a 25mm floor is a lot thinner than allot of people are using (56mm). Rick
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Post by g20wey on Mar 21, 2017 14:06:53 GMT
Matt , I laid my base onto a thin screed of mortar, a 1,1,1 mix of fire clay, sand and cement, but a thin layer of fire cement would be OK but this is only useable at a max thickness of 5mm. I've had a look at a video on the Melbourne FC web site and they are covering the board with what looks like a refractory 'heat base'. I think this is to add thermal mass to the base as a 25mm floor is a lot thinner than allot of people are using (56mm). Rick Hi Rick,
Do you think that 25mm base bricks would be too thin then as I've already purchased them?
How thick did you lay your screed? Was this straight on top of the foil laid on the calcium or did you set a mix first all the way over as the Melbourne company did?
Thanks again
Matt
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Post by moonhead on Mar 23, 2017 8:42:25 GMT
Hi Matt - depending on what you intend to use the oven for, if it's just pizza then the floor bricks will be fine. If you want to use it for bread or slow roasts then as you will have read in many threads on the forum it's about thermal mass. The more mass you have the deeper the heat penetrates so the longer the oven will retain heat after the fire has died. If it's the latter then you may want to think about adding a layer under your floor on top of the cal sil board. Possibly a layer of storage heater bricks, these have been used by builders on this forum for bases as well as ovens instead of fire bricks. Rick
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