URGENT oven dimensions

[Acoma]

The mortaring of firebricks to the insulation board is not so important due to expansion factors, and requiring of similar expansion of mortar, brick. This is why people say to use HIGH TEMP mortar for the dome and arch (Refmix). I have read to many threads of people regretting using heatstop 50 as mortar due to its inferior ability to bond at these high temps. I have paid a pretty penny on quantity of Refmix betting my oven it will be the best. This is not a puzzle, you will build it, it bonds, it stays or fails. As for the cement from hearth bricks to ISO, if you redo the brick to ISO, scrap the cement, not as important as insulation factors needed for foods. This is why I say, if you have not started the dome, go back a step now! More ISO, and I say 3" total for floor. In the end, you will smile always..

[Dutchoven]

I agree...most builders use just a slurry of fireclay/sand and water to level the bricks...or nothing at all if you have a nice level hearth slab

[gjbingham]

Agreed. Two inches of the Iso board is probably minimum. The plans call for fireclay and water to set the oven floor brick in, then tap them into place. Take your time. Make it great!