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samuraistu 08-23-2011 04:01 PM

oven floor insulation question
Hi all,

I have recently completed my stand and am finally ready to start work on the oven dome but I am bit lost to what is the best oven floor insulation to use.

I did contact a fellow FB user, who also lives in Japan and he recommended a kiln company where he bought his fiber board and fiber blanket from, but the fiber board is way too expensive for me. For a 90060050 board it will cost 11,550 (150 dollars a board) and they only come in sets of 2.

So I started looking into vermicrete which looks relatively easy to do but then I stumbled across posts in the forum talking about calcium silicate board.

What I would like to know is what is best, vermicrete 4" or Calcium Silicate board or both.

I hope someone can help

Cheers in advance.


dmun 08-23-2011 04:08 PM

Re: oven floor insulation question
Cal-Sil board is the best, but it's more expensive than mineral fiber board. Vermiculite or Perlite concrete will work fine if you have 4" of height for it.

Laurentius 08-23-2011 04:55 PM

Re: oven floor insulation question
Hi Samuraistu,

I was hoping that you had finished and was enjoying your oven by now. I'm helping a monk build an oven at his temple. Good luck on your oven.

samuraistu 08-23-2011 05:04 PM

Re: oven floor insulation question
Hey Laurentius, Yeah I was hoping to be enjoying my oven as well now but between the wife and kids and work it's hard to find time. But I'm getting there slowly. Regards to the ceramic fiber board from the company you recommended how much did you need and how much did you pay?

Laurentius 08-23-2011 07:12 PM

Re: oven floor insulation question
(3) Ceramic Fiber Blankets Y39,060
(3) Ceramic Fiber Boards Y34,650
I would purchase them again in a heart beat, I've had over a dozen people to contact me with non or under insulated oven here. How long have you been here? You have got to stop comparing Japanese and American prices, you are being paid in Yen, right. I still order many things stateside, because they're cheaper to buy and ship here than to buy here

tektonjp 08-25-2011 05:43 AM

Re: oven floor insulation question
I got a 50 liter bag of vermiculite at the local home center for 1200 yen. 400 for a bag of cement. May not reach the level of the ceramic stuff, but a 10 centimeter thickness should work, I'm thinking.
I plan on casting in place using Asahi Casting cement. But the prices have jacked up this year. Ouch.
Scott in Shiga

samuraistu 08-25-2011 04:02 PM

Re: oven floor insulation question
Scott, are you planning on using the Asahi Casting cement instead of Portland with the vermiculite? Which exact type of Asahi cement are you using? I checked their website and they have quite a few products.

tektonjp 08-25-2011 05:19 PM

Re: oven floor insulation question
For the insulating base, I plan on regular Portland with the vermiculite. Getting ready to do it this morning but a quick glance made me realize that 50 liters was about half of what I need. Off to buy more when the store opens. I'm placing it over some 12mm Durock cement board which has been laying around my shop for years.

The casting cement will be for the dome. I think the 13T is what I'll try. It says it is for troweling. The 13S is for hand packing in a form or when using mesh. Actually, having never done this, I'm not sure what is best. As I will be casting in place over a sand dome with the brick arch already in place, part of me says to get some stainless chicken wire and do the 13S. And the other part of me says, it's a 60cm dome and it is all kind of an experiment. The web site says this is refractory concrete. It should be fine.
I'm taking photos and will try to start a thread this weekend.
Where are you located?

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