hearth Insulation question

[sonomacast]

have built an oven and floor out of refractory castable (See my other posts). I wish to mount this oven onto a trailer, I'd like to know would there be any problems if I were to sit the oven directly onto a sheet of plywood and placed rigid urethane insulation (3") Under the plywood for ease of mounting or would the insulation need to go directly under the hearth (The floor is 3" deep. Thank YOU

[dmun]

I don't think you want anything combustible next to your oven floor. That would rule out both plywood and urethane.

[sonomacast]

The product I wish to use is called Kingspan here in the UK. I guess you have similar products abroad. It is a rigid foam with a silver paper outside. I used it before on an other oven and it worked very well. What do you suggest as a hearth insulator?

[shuboyje]

Kingspan is a phenolic foam. It is only good to about 300f for continuous use. I'm in the middle of being certified on their products as we speak.

[dmun]

There are lots of non-combustible choices. If you want a rigid foam, There are multiple mineral fiber choices, as well as the more expensive calcium silicate. These are both refractory products. If cost is an object, perlite or vermiculite can be mixed with portland cement. Builders have also used foamglass, an expanded glass block, or
Autoclaved Aerated Concrete aka Hebel Block, although there have been some problems with brittleness reported with this.

There's no reason to use things that are going to outgas fumes or smoke in your build.

[sonomacast]

Originally Posted by shuboyje

Kingspan is a phenolic foam. It is only good to about 300f for continuous use. I'm in the middle of being certified on their products as we speak.

Kingspan is the number one insulation panel product used here in the UK, It is actually shipped here from Ireland and costs a fortune to buy, However as I am in the construction industry I have been hoarding leftovers. Shame i can't utilize it to be used in my oven. Thanks all for your help