Hi All,

New user, first post, so please excuse me if I am doubling up on previous posts (I have tried searching).

I've started building a 42" Pompeii Oven using the Pompeii Oven Plans Version 2.0. These instructions are awesome, but I am struggling to work out a small part regarding the hearth. My wife and I are big bread makers, and plan on making high volume breads with this oven along with pizza.

On page 28 of the instructions, it show how you could add extra heat mass by sinking a brick island into the insulating layer. It says to take care not to reduce the your insulating layer to less than 3.5 inches.

Does this mean that the hearth is comprised of the 3.5 inches of structural concrete, then a 3.5 inch insulating concrete layer, followed by the layer of firebricks that make up the extra heat mass under the cooking floor which could then be surrounded by normal concrete?

I can't imagine that the extra firebricks being set into the 3.5 inch insulating layer would be safe, as it would only leave an inch or so of insulating concrete before the structural concrete layer. If I built the hearth layer as a 9.5 inch rather than 7.5 (being 3.5 structural concrete, 3.5 insulative concrete, 2.5 firebrick surrounded by either insulative or structural concrete) would it be a bad, unthinkable, or unrecommended configuration?

Thanking you in advance!