Okay so I have a 5’ by 5’ square sand patch of land I’m turning into a fire pit

I’m putting down gravel and then paver base. So I’ll have the layers of sand, then 2” of gravel and then 2” of paver base.

I’ll then be building a circular fire pit out of retaining wall blocks that are trapezoid shaped

I’ll leave about a 2” gap all around then in the center I’ll put a fire ring that’s 35”.

I’ve read some say fire bricks are super important.

Should I be incorporating fire bricks or am I fine? If I do need them, would I only put them under the fire ring or under both the fire ring and the circular stone walls?