Perlite Yoga Ball Build/ Floor question

[Pizzalover2]

Hello all,
I went with the Yoga ball Perlite/Portland cement build method.  Looked great and think it will hold heat in well. One problem I discovered I made was, I accidentally used the lighter weight fire bricks on the floor instead of the denser more yellow ones.  I realized on my first fire that the floor did not hold the heat and radiate as I thought it should.  I think I could solve this with going over it with granite, steel, or some kind of tile but not sure what would be best, least expensive and easiest. It also got me wondering then if the walls of the dome don't radiate enough since the perlite mixture is also quite insulating.  Should the inside be coated with something to retain heat or does that not matter as long as it holds heat in the oven?  Thanks for any help, Craig

[Jon in Albany]

I've heard of the yoga ball method, but never with perlite. Also, I'm not sure what bricks you used for the floor. Are they food safe?

My first reaction to what you have written is that you made an oven out of insulation, but no real mass to insulate.

Some photos would help, but a wild off the cuff guess would be putting an inch or so of refractory concrete on the dome. I imagine this would be very difficult to do. And put the right firebrick on the floor (Whitacre Greer is a trusted name in firebrick), or maybe firebrick splits. I suppose you could start with the floor and then cover the floor if you need to work on the dome. But also keep in mind that putting the floor in will also reduce the space you have to work inside the oven.