Hearth Insulation Alternatives

[Lordnorton]

Hi guys, I'm looking at starting to build my own pizza oven I have built the platform to stand it on out of reinforced standard concrete but understand I need an insulating layer on top of that before the oven floor. My question is as I wish to keep the costs low is there an alternative to fibre board or casting Vermiculite? I have a fairly large supply of fire bricks from work including some light weight white ones called TDM28 I was wondering if I could use these instead?

Any Help is much appreciated.

Cheers
Mark

[UtahBeehiver]

If you have access to "true" insulating fire brick (IFB) at a good cost, they are a good option for floor insulation under the regular fire brick. IFB are lightweight, ie 1 - 3 lbs each, easily scored with a knife or fingernail), they roughly have a thermal characteristic of 0.14 W/M at 400 C vs CaSi board at abt 0.07-8 W/M at 400 C. If you access to them then it is a viable option. V-vrete or Pcrete are inexpensive options just takes more thickness to get the same thermal insulation. Need to confirm that the TDM28 themal characteristics and ensure they are IFBs.

[Lordnorton]

Thanks for the reply I've tried to link the fact sheet but can't get the link to work. These are free from work so would like to utilise them if possible for under oven floor. I also have access to TDM26 which seem much softer and can be scratched with fingernail. They are used to line our ceramic ovens at work.

Cheers
Mark

[UtahBeehiver]

I looked at the brick specs on the IMS site and the TDM IFBs have thermal ratings of about 0.29 - .30 W/M C so it is higher than CaSi board 0.07-9 W/M C by a factor of 2-3. That said, free is free, You might need to consider laying the IFB on edge rather than flat so you have more insulation thickness. From what I can see the smaller the TDM number the less dense the brick is. This is your call good luck. FYI, these bricks are not for the dome or the main cooking floor.