Insulation vs. Wall thickness

[das]

I am looking to build a 36" Pompeii oven, and I am curious as to whether I could help with the heat time by cutting the fire bricks to say ~3.5" instead of the common 4.5" (halves) but then bulk up the exterior insulation to 4 or 4.5" and still get maintain the heat retention properties for next day roasting.

Also do you guys think upping the floor insulation to 3 or 4" of ceramic board would be beneficial. Seems many have had issue getting the floor up to temp in under 90min. going with the standard 2" or vermicrete base.

Does anybody have experience with the FB Premio which uses a 3" Ceramic board base, 3" refractory dome, and 4" of insulation. Curios how much of a difference the added insulation makes and if the Pompeii's can benefit equally?

Lastly, how does the insulation FB sells compare to Unifrax Duraboard and Durablanket, as well as other options from Thermal Ceramics, is the FB stuff imported from China? From looking around it seems there are more expensive as well as cheaper options, which is the best stuff for the money, without compromising long term stability etc.? If I can use cheaper stuff them adding extra insulation would not cost much more.

Thanks for the help.

[Mike D]

I am still building my oven, but I did double my floor insulation (2" board and 3.5" of vermicucrete). I don't know what a 3.5 thick dome would do. I would say that you can never have too much insulation.

Mike

[das]

Thanks for the reply Mike, your build is looking great, did you buy the kit or source locally?

I called FB this afternoon and they said the amount provided is optimized, and any additional is overkill. Yet, what I find interesting is that on the Premio, which uses the same 2.5" firebrick floor tiles as the other modular ovens and pompeii kits, comes with 3" base insulation.