Hand mixed the perlite/vermiculite/cement mix at 2.5 : 2.5 : 1. Bucketed it up to form and screed off. The added weep holes worked as expected. Will leave now to dry out before adding a fine layer of bedding sand to lay floor bricks.
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Just a heads up. You are putting a lot of effort into this build and we all want the oven to be a success. I am concerned that the 2.5 to 1 pcrete ratio is not going to give you the needed insulation in the floor. I sent out a post showing the K values of pcrete and recommended 5 to 1 with a min of 4" with 6" better since it takes almost twice the thickness of pcrete vs CaSi board. This post, unfortunately went out when the site was hacked so I do not know if you saw it or not. There are a couple options, add another more pcrete (5 to 1) or add layer of CaSI. Proper floor insulation as well dome insulation is key to an effecient oven. Just trying to watch out for you and all your hard work.Comment
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So UtahBeehiver the mix I have done of perlite/vermiculate (5) to cement (1) won’t be sufficient?Comment
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In the post, I thought it said 2.5 to 1 not 5 to 1. 5 to 1 is the correct ratio structural rating for a floor. It has a K value of around 0.72-75ish with CaSi having a K value (depending on temp) of around 0.5. Our rule of thumb (conservative) is twice the thickness of pcrete to CaSi thickness. Bare minimum floor thickness of 5 to 1 pcrete is 4" if the ratio is 2.5 to 1 then the K value really shoots up. If it was a typo on the post 2.5 to 1 and is really 5 to 1 ratio you will be at the minumum recommended floor insulation.Comment
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I went and read the post closer, so it is 5 to 1 half perlite and half vermiculite to portland. It will still be at the lower end of the insulation scale. If you are wanting to do serious extended cooking, brick heat saturation is most important with minimum K value. The insulation on current oven will be fine for pizzas and some extended cooking. So it is up to you. Sorry I misread the post.Comment
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