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  #11  
Old 06-25-2013, 10:22 PM
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Join Date: May 2013
Location: Ireland
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Default Re: Drying out vermicrete hearth insulation slab

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Originally Posted by david s View Post
The air spaces between the vermiculite grains provide the air space, but you must make the brew lean to achieve this. I use 10:1. Also don't compact it too much.
Thanks David. That's 10vermiculite to 1 cement? I assume it still has the strength to hold the done shape? Do you use any chicken wire or mesh of any sort in the structure to help it hold shape?
Thanks
Richard
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  #12  
Old 06-26-2013, 03:29 AM
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Location: Townsville, Nth Queensland,Australia
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Default Re: Drying out vermicrete hearth insulation slab

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Originally Posted by RichC View Post
Thanks David. That's 10vermiculite to 1 cement? I assume it still has the strength to hold the done shape? Do you use any chicken wire or mesh of any sort in the structure to help it hold shape?
Thanks
Richard
Yes, 10 vermiculite 1 cement. I mix it dry and add 3 parts water. No mesh.
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  #13  
Old 08-09-2013, 08:40 AM
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Default Re: Drying out vermicrete hearth insulation slab

Hi Guys,
Ive started putting in the vermiculite hearth insulating layer. I'm keeping if covered and intend covering it with a polished concrete countertop after the dome and dome insulation goes on. Then the last step will be the (hopefully) 'weatherproof' render for the dome. this should allow water to run down the dome and off the polished concrete countertop. although I'm trying to keep it covered, in my damp, windy climate the vermicrete is definitely going to hold some moisture. I think I'm going to drill down through it in the 4 courners and the centre to create 5 weep holes as Gulf recommended. Ive only about 60mm of vermicrete down so far, so the holes will fill with vermicrete when I finish the insulating layer off.
My worry is that it'll be sealed when the concrete countertop goes on so how will it dry out when firing? How does moisture evaporate away or does it just happen because nothings 100% waterproof anyway??
Also, I was thinking of putting a layer of plastic between my concrete countertop and the vermicrete slab to prevent any water getting back into the vermicrete from the top. Would this be counterproductive when drying out? Good or bad idea?

Thanks!

Richard
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  #14  
Old 08-09-2013, 12:56 PM
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Default Re: Drying out vermicrete hearth insulation slab

Richard,
Your fires will eventually dry the stuff out, but it may take months.mThat's why I believe it's better to lay the stuff in layers with a week between each to let the sun and wind dry it out somewhat (but keep out the rain) The water eventually finds its way out. It will migrate back to the porous floor bricks a little between each firing. Try to slope your countertop away from the dome to discourage entry where the dome meets the countertop.Adding an admixture to make the countertop waterproof will also help, alternatively your plastic sheeting barrier will achieve the same.
Dave

Last edited by david s; 08-09-2013 at 12:59 PM.
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