Brick hearth evenness

Posted by John K

Thanks to Rado's pictures showing the way the fireclay and find sand should be applied to the concrete base for my hearth, I thought that I should have a perfectly flat and well matched brick base for my oven. What I have found is that the firebricks are rarely flat on all sides. While I have been able (two tries thus far) to make the floor generally flat, there are gaps (some as large as 1/16 to 1/8") between some of the bricks due to a lack of flatness on some of the sides in almost all of the bricks. These are new bricks from a major masonry supplier in my area. My questions are: (a) are these gaps going to create problems later on, (b) is there any way to correct for these brick variations and (c) is there any way to fill in these small gaps?

Brick hearth evenness