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Post by SentencedToBurn on Dec 17, 2016 11:10:15 GMT
Hey great point thanks mate, will defintiely do that.
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Post by SentencedToBurn on Dec 18, 2016 5:00:20 GMT
Managed to get some more bricks to put underneath the main "oven" part, whatever the correct term is. Also followed chas's advise and positioned the floor bricks point on. This week I'll look through youtube videos on how to apply mortar as I have no idea what I'm doing, and next weekend will just crank into it and do the foundation and the 3 walls around the door. Will only go as high as the lowest part of the arch above the door. Actually, someone might know, is this method here good for cutting bricks: www.thisoldhouse.com/more/how-to-hand-cut-brick ? Or should I just get concrete cutting disks and chop them up with a grinder?
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Post by slen916 on Dec 18, 2016 9:19:40 GMT
i would go with the grinder method or a wet cut table saw is the best way.
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Post by SentencedToBurn on Dec 18, 2016 19:35:14 GMT
i would go with the grinder method or a wet cut table saw is the best way. Cool thanks I'll look that up
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Post by downunderdave on Dec 18, 2016 23:59:03 GMT
As previously advised, you need to insulate under the floor. This becomes even more important if your floor is two bricks thick as heat takes around an hour per inch of thickness as rate of travel. So while you are heating the top layer, The bottom layer is sucking heat from the top layer in an effort to equalise the heat. Without insulation the heat is escaping and makes the whole process take even longer. Most modern ovens use a floor thickness of 2" with a decent amount of underfloor insulation. A floor with two layers of brick is more suited to baking multiple loaves of bread, where the high temperature for pizza is not required, but high thermal mass is. By all means take no heed of the advice, build your uninsulated oven and discover you were wrong. However, adding underfloor insulation after the build is done is extremely difficult, if not impossible.
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Post by SentencedToBurn on Dec 20, 2016 3:53:49 GMT
So I already had some of this set aside for the foundation under the bricks, however I think i'll only have about 1 inch all up if I'm using 5x1 ratio: I also have some of these clayballs that I use for my hydro plants, I have quite a lot of them. I wonder if I can use these as part of the vermicrete mix to increase the volume? Or should I only use vermiculite and concrete?
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Post by downunderdave on Dec 20, 2016 11:58:10 GMT
Yes, those clay balls called LECA (lightweight expanded clay aggregate) can be used in the mix with vermiculite, but you will need to make the insulating layer at least 3" thick, preferably 4". The LECA balls will make theslab stronger. A 5:1 mix using equal parts of vermiculite and LECA works well.
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Post by SentencedToBurn on Dec 20, 2016 19:03:11 GMT
Yes, those clay balls called LECA (lightweight expanded clay aggregate) can be used in the mix with vermiculite, but you will need to make the insulating layer at least 3" thick, preferably 4". The LECA balls will make theslab stronger. A 5:1 mix using equal parts of vermiculite and LECA works well. Thanks Dave, in that case I'll make it just using these clay balls and vermiculite. The bricks I'm using are 230x115x75, so i'll leave the bricks on the sides (which won't be part of the bottom of the oven) and will keep them as a retaining wall. So this gives me 3" if I fill it all the way to the top. If I have enough I'll then build on another inch on top of that.
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Post by downunderdave on Dec 20, 2016 20:03:51 GMT
But that still only gives you one inch of underfloor insulation, You need at least 3 preferably 4, if using that mix.
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Post by SentencedToBurn on Dec 20, 2016 22:56:24 GMT
But that still only gives you one inch of underfloor insulation, You need at least 3 preferably 4, if using that mix. Hey Dave, I mean I'll layer it on the height of a single brick, which is 75mm = 3". So on the last image, where I've added the additional bricks (the narrower ones) - those bricks will be replaced with clayballs/vermicrete mix, and my clay bricks will then go on top. So the "oven base" bricks will be sitting on at least 3" of vermicrete/clayballs. Actually here is what I mean:
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Post by downunderdave on Dec 21, 2016 1:38:01 GMT
Yes that is better. Are you planning on a rectangular footprint? Also are you planning on having an entry and flue? It appears that your oven interior will be 460x575 mm You could increase this by laying your bricks on edge although this reduces the bond between bricks. Alternatively cast the walls and roof with a dense castable refractory, in which case you can reduce thickness to 50 mm. Your steel support under the insulating slab is prone to rusting from trapped moisture so several holes drilled through it is useful. Cover them with insect screen so the insulating mix won't fall through.
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Post by SentencedToBurn on Dec 21, 2016 2:19:51 GMT
Yes that is better. Are you planning on a rectangular footprint? Also are you planning on having an entry and flue? It appears that your oven interior will be 460x575 mm You could increase this by laying your bricks on edge although this reduces the bond between bricks. Alternatively cast the walls and roof with a dense castable refractory, in which case you can reduce thickness to 50 mm. Your steel support under the insulating slab is prone to rusting from trapped moisture so several holes drilled through it is useful. Cover them with insect screen so the insulating mix won't fall through. I thought of doing the bricks on edge however will probably stick with them flat down to keep it stronger since I know the roof adn the arch above the door will probably put a bit of stress on the bricks. The interior space will probably be just enough I figured. I'll probably stick with the bricks instead of a cast, part of the idea is to go for a "castle" look. So even if I can only do small pizzas - I'll be happy as long as it looks sweet. Good point about the metal support - at the moment it's just a steel sheet, will drill some holes out and I have some fine steel mesh so will spot it over the holes. TBH I didnt think of having a flue - I was only aiming to have a door and a chimney. Unless it's a good idea to have one?
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Post by SentencedToBurn on Dec 23, 2016 2:28:59 GMT
Pretty much ready to pour in the insulation mix, just gotta drill a few holes on the bottom tomorrow and chuck some mesh over them, and we're ready to go.
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Post by SentencedToBurn on Dec 24, 2016 0:31:11 GMT
I used 5:1 ratio, and filled the space to the top. Will see how it looks tomorrow once I remove the wooden boards. Whether it'll be hard enough for me to lay the first bit of foundation.
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Post by downunderdave on Dec 24, 2016 8:53:15 GMT
I used 5:1 ratio, and filled the space to the top. Will see how it looks tomorrow once I remove the wooden boards. Whether it'll be hard enough for me to lay the first bit of foundation. Because vermicrete requires a large amount of water in the mix, you probably added more than a bucketful, it is difficult to eliminate by fire. Less than half of it will be taken up by the hydration process, leaving a large amount behind. As you are in your summer, instead of building over it and locking in the water, you can let the sun and wind do much of the work. In ideal conditions a 3" vermicrete slab will take 3 weeks to dry out, if you can bear to wait that long.
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