Can i modify an igloo shape to 36X39? what problems will i encounter?

[JohnWPG]

Hi have built a Tyndall stone foundation and i have room to build a barrel vault oven on it. I had planned to build a 36" igloo dome.
Question - Are there heat / smoke circulations issues or structural issues if i make the dome oval / oblong 36x39.

30 second timelaps of my foundation build

John from Winnipeg

[JohnWPG]

Second Question - i will have a solid foundation filled with old patio bricks. I am going to use perlite as the insulation layer beneath the cooking floor.
Can I use loose perlite or do i need to bind it into a solid by mixing with a Portland cement?

related question, i see that there are many more posts referencing vermiculite than perlite? why is that? is vermiculite preferred?

[UtahBeehiver]

Loose perlite or vermiculite does not have the compressive strength to support an oven (min 75 PSI), The dome also needs to be insulated from the hearth or the hearth will act as a heat sink. A min of 5 to 1 v or pcrete under the floor and oven is recommended a bare minimum of 4" thick. Perlite or vermiculite will work, what ever is easier to obtain.