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Post by webbm00 on Jan 28, 2019 20:42:17 GMT
I think the instructions create a bit too solid connection to the oven as it ask for a joint of mortar between the arch and oven and ties. I like downunderdaves idea of tying it to the vermicrete layer which is above the thermal blanket and a bit more isolated from the expansion of the oven. I'm a bit worried about the lateral forces of the arch pushing the top of the abutment and creating cracks but I guess once the vermicrete and render is on its held firm?
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Post by truckcab79 on Jan 28, 2019 21:35:26 GMT
Kind of what I figured with mine. The line of bricks forming the start of my brick chimney run over the top of the arch so it can’t really go anywhere.
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Post by downunderdave on Jan 29, 2019 10:08:05 GMT
I think the instructions create a bit too solid connection to the oven as it ask for a joint of mortar between the arch and oven and ties. I like downunderdaves idea of tying it to the vermicrete layer which is above the thermal blanket and a bit more isolated from the expansion of the oven. I'm a bit worried about the lateral forces of the arch pushing the top of the abutment and creating cracks but I guess once the vermicrete and render is on its held firm? I guess it depends on how strong you make the vermicrete layer, but if you want it to be quite insulative then it will have little strength.I use 10:1 (see table for strength/K values). Better to tie the arch into the outer shell which is way stronger.(See pic)
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Post by webbm00 on Jan 29, 2019 17:24:29 GMT
I think the instructions create a bit too solid connection to the oven as it ask for a joint of mortar between the arch and oven and ties. I like downunderdaves idea of tying it to the vermicrete layer which is above the thermal blanket and a bit more isolated from the expansion of the oven. I'm a bit worried about the lateral forces of the arch pushing the top of the abutment and creating cracks but I guess once the vermicrete and render is on its held firm? I guess it depends on how strong you make the vermicrete layer, but if you want it to be quite insulative then it will have little strength.I use 10:1 (see table for strength/K values). Better to tie the arch into the outer shell which is way stronger.(See pic) Is that the render over the vermicrete? and are the wires just attached to the arch or pulled tight around the dome?
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Post by downunderdave on Jan 29, 2019 19:27:56 GMT
Yes, the wires are firm against the vermicrete using a 90 degree twist with a pair of pliers if any are a bit Ioose. I used to use chicken wire, but it is very time consuming so now use random fibres mixed into the render, much faster.I then wrap the whole thing in cling wrap for a week to retain moisture in the outer render to enhance strength.
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Post by webbm00 on Feb 1, 2019 11:44:45 GMT
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Post by webbm00 on Feb 3, 2019 20:40:14 GMT
Got the rest of the bricks for the arch cut today It's still going to be below 5 until Wednesday and then ok till Sunday so hopefully if the rest of the glass and shells arrive I'll cast another test piece of Wednesday
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Post by webbm00 on Feb 9, 2019 23:03:11 GMT
Got the vermicrete layer on today. What a pain in the arse to get it to stay on the dome. By the third mix I'd just about got the amount of water right to make it usable. And yes downunderdave it was another pain in the arse to get down the back of the oven as it's in a corner But at least that jobs done now The kids want a mosaic on the side after seeing oblertones octopus on his oven so we are now finding suitable designs for that as well as waiting for the shells for the worktops. Still enjoying the journey but want it to turn into pizzas at some point
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Post by downunderdave on Feb 10, 2019 20:21:02 GMT
It’s up to you of course, but I always do the drying fires after the vermicrete layer and before rendering the outer shell. This reduces the steam pressure build up in the insulation layer that can create cracks in the outer shell. It also provides an easier, less restrictive path for steam to find its way out. Also, if you see visible steam then you are going at it too hard, back off,
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Post by webbm00 on Feb 11, 2019 7:43:22 GMT
It’s up to you of course, but I always do the drying fires after the vermicrete layer and before rendering the outer shell. This reduces the steam pressure build up in the insulation layer that can create cracks in the outer shell. It also provides an easier, less restrictive path for steam to find its way out. Also, if you see visible steam then you are going at it too hard, back off, You just preempted my next question. I just need to put the damper in the flue and then seal it in before the first drying fire
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Post by oblertone on Feb 12, 2019 11:12:00 GMT
If you're considering a mosaic finish then seek out waterproof tile cement rather than render; it's more expensive but you'll be using it anyway.
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Post by downunderdave on Feb 12, 2019 20:00:18 GMT
If you're considering a mosaic finish then seek out waterproof tile cement rather than render; it's more expensive but you'll be using it anyway. Look for, outdoor/exterior rather than interior, tile adhesive.
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Post by webbm00 on Feb 12, 2019 20:19:39 GMT
If you're considering a mosaic finish then seek out waterproof tile cement rather than render; it's more expensive but you'll be using it anyway. Look for, outdoor/exterior rather than interior, tile adhesive. I assume use this instead of rendering the dome? Or do you use this where the mosaic goes and render in between? I ask this because we will probably have a few creature mosaics dotted around the dome but none at the back
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Post by downunderdave on Feb 13, 2019 6:39:55 GMT
The usual is to wrap the vermicrete or perlcrete layer in chicken wire and render over it with a cement based render. I find that too fiddly and time consuming and now prefer to add random AR glass fibres into the render. You could use tile adhesive instead of the cement render, it may work but is not designed for that purpose. For grouting the mosaic you should buy tile grout though, it is pre coloured and has finer sand and more waterproofing in it than standard render. Because you are so close to the walls you will find it difficult to render at the sides and the back let alone mosaic. (But I think I warned you about that when you started)
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Post by oblertone on Feb 13, 2019 8:30:27 GMT
My build thread is linked in my signature line; I used waterproof tile cement as render for the whole dome. It's worked so far.
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