Hey I built a 4'x4' concrete form the inside measurement is 3'x3' the walls measure aprox 6" thick.I am looking to line the walls with fire brick to protect the concrete from heat. Do I just need 1 layer of brick or 2 i'm sure 1 layer of brick would be fine i'm just used to over building things. what are the pros and cons of layering it. what type of mortar do i use ?The walls are 28" tall but i plan on fire bricking the total height then fill in approx half of it with gravel or dirt to be the bottom or 'Hearth" of the pit which filler material would be better.
Thanks
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