Oven floor insulation

[Gulf]

Re: Oven floor insulation

If you are leaning toward pairing insulations, you might want to think about Calcium Silicate (CalSil) and vermicrete. Heck, if you did some searches locally for CalSil, you might find that it is cheaper to go that route. Search locally for industrial or commercial insulation suppliers in your local area.
EDIT: I should have read thru your post again. I see that calcium silicate was one of your options. Based on my research, recomendations from this site, and my local pricing: 2" Calcil and 4" of 5-to-1 vermicrete gets my vote.
I think that your 3 and 1/2" vermicrete would be sufficient.

[LGM]

Shout out to everyone on the forum! Much praise to all of you builder ?veterans? willing to take the time to share your experience/expertise. It is appreciated by us ?new guys.?

So, I?ve built my foundation and base, now I?m ready to move forward with building the dome. Having some difficulty deciding on the dome floor insulation. Looking for some opinions!
Originally, I was going to build a 40? oven. However, after some calculation, I realize that the oven would be 49? wide (outside diameter). Since the ceramic board comes in 24?x48? sizes, I have decided to pare down to 39?, making the outside dimension 48?. According to my calculations, this would mean I need approximately 3 pieces of 2? thick, 24? x 48? Ceramic board (FB).
However, this stuff is pretty expensive!
I have read some threads and noticed that some wished they had more insulation under the floor.
Thinking about putting a layer of vermiculite mix under 2? of ceramic board.
This is the part where I would appreciate your opinions.
Is ceramic the best to use?
How do the mineral boards, such as Insblock 19 perform? (seems to be much less expensive!)
Or other alternatives like calcium silicate boards, such as Superisol board?
Would 3.5 ? of vermiculite mix and the 2? of ceramic be a recommended approach or swap the ceramic for 3? or 4? of Insblock 19?
Thanks,
Larry
Gratzi mili tuti