Hearth insulation confusion......Help

[sonomacast]

I have built a cast segmented oven which weighs over half a ton and intend to put it on a trailer. The hearth is 3" thick (as are the oven walls) I have built the frame in my trailer and the top layer so far is going to be marine ply. Now obviously I can't put the oven straight on the plywood (I persume given time it would burn) I was wondering if I made vermiculite cement (6-1) at 1" thick and also put 1" ceramic blanket under the hearth would it protect the plywood base? failing this I have a lot of house insulation (Kingspan here in the UK) It's basically dense foam woth aluminum paper on each side. I was thinking of usint this but I don't know how it will stand so much heat and weight over time... Any ideas or pointers, sorry but insulation board is not an option right now and i need to save as much weight as i can hence the 1" of vermiculite cement. Thank you

My oven so far--- http://www.fornobravo.com/forum/f21/...day-16182.html (My latest precast oven, struck today)

[mrchipster]

The insulation board is not very heavy and the blanket will crush under the weight of the floor.

You will be able to carry much less wood if you insulate the floor well. And that would be a 2 inch layer of insul board.

Just my two cents.

Chip

[dmun]

Don't use domestic insulation to insulate your oven. It will burn and stink, as it has organic binders.

[sonomacast]

Insulation board is so expensive here in the uk and it seems hard to find.any alternative suggestions.

[Ken524]

Vermiculite/portland may not hold up with the road vibration. You really, really want to use board. You might email a few US places and see about having it shipped, but local board may be cheaper than that.

Don't skimp on the floor insulation. This is the one area of your oven that you MUST do correctly the first time. Bite the bullet and get a 2-4 inches of board.

[casper]

That looks great, but I am wondering why you made it so big if you want to keep it portable.

I suggest you keep this in your back yard and make another to fit on a trailer... which you would need to be braked double axle to prevent it tipping.

This is the FB insulation board link
http://www.fornobravo.com/PDF/FB_board.pdf
as you see it is 3 to 4 times better than vermiculite so is much lighter and compact.
You can get it for less than 80 quid from a refectory builder's yard. My local one has offcuts which I collect from time to time, no charge/beer money