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chale 09-13-2008 05:12 PM

Installing Ceramic Board
My first post and well involved in the pompeii construction.

I have decided to go through with 2" of ceramic board installation over the supporting concrete. My questions is, how much of the ceramic board do you need as surface area, e.g, do you need just a circle under the oven only or do most people make a rectangle or square that is bigger than just the dome? My second question is since you place the ceramic board 2" tall, what is placed around the rest of the remaining supporting base that does not have the ceramic board on top of it. If I was using the vermeculite insulating concrete, the entire surface would be elevated rather just a circle or rectangle.

Thanks in advance,


Wiley 09-13-2008 07:15 PM

Re: Installing Ceramic Board
I did my insulating layer as a square with the width equal to the greatest dimension of the heat sink and insulation (in the case of a brick oven the area under the bricks plus the insulating material). I would suggest taking the time and cutting a circle with that diameter IF you are going with a dome/igloo as opposed to a small gable ended building for your final enclosure. As a result of my error in making the insulating layer a square rather than a circle (and wanting an igloo/dome structure) I had to dig out the insulating layer where it extended beyond the the insulation of the dome and refill that area with concrete. This was to keep the possiblity of water intrusion into the insulating layer to a minimum. The original plans had a complete layer of insulating material across the whole dimensions of the WFO(percrete or vermicrete or whatever). I had issue with this regarding water infiltration and so contained my insulation within a curb of concrete... although as I said, I made a square rather than a circle and so had to correct that error. (I never claimed to be clever... only Wiley :-) My outer shell sits upon concrete not upon insulation.

If you are building a square structure for your final shape then it probably matters little whether the insulation is greater than need be as the whole will be enclosed and so protected.

As a young man I worked in boat yards and water will find a way in if it at all possible. As a general rule chasing leaks in the topsides is always more of a challenge than leaks thru the hull. In the case of our WFOs water seaping into the insulation would seriously impact the temps and durability of the oven.

chale 09-14-2008 07:34 AM

Re: Installing Ceramic Board
Thanks for the reply.

I am going to have a gable rather than the dome exposed.

How do you integrate the fiberboard under the landing?

If you have the fb under the dome and insulating width and don't do the landing, they won't be at the same height. However, if you extend the fb to underneath the landing, even if you are doing a gable, the landing is going to be higher than the areas just to the left and right of the landing.


Wiley 09-14-2008 09:52 AM

Re: Installing Ceramic Board
Charles, Not trying to be rude but I think I would suggest you find a thread where someone is or has been building a WFO similar to what you are envisioning building and follow entry by entry. Most of us who have created threads of our construction have included lots of photos and they might help answer your questions. The old saw about "a picture is worth a thousand words" thing.

My construction is different than most but I think one could follow what I have done by reading the thread. If you read it you will see how I handled the bottom insulation; and where I went with a square where I would have been better off had I gone with a circle or perhaps just lopped off the corners of the square and gone with an octagon. I think pouring the bottom insulation like I did is the way to go as the insulation really acts like a sponge soaking up any and all water that comes near it. Easy to get wet and slow to dry out. Also for building a walled structure one could incorporate "J" bolts and more securely anchor the structure rather than nailing into the vermicrete or perlcrete. But what do I know? I can imagine a structure attached just to the insulation might have problems if it were subject to winds like from a hurricane. So that might make one design different if they were building in say Florida as opposed to Colorado. Likewise a large stone or brick structure might fair less well if it was subject to an earthquake as opposed to a lower lighter structure like a dome with stucco. But we all do our best within the limits of our experience and budgets and ability to assess the risks involved with each type of construction.


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