Hi, all. I have decided to redue my shower stall but keep the tiled shower floor because it is in good shape. When I removed the walls there was a 1/2 inch gap between the floor and the studed wall. (the shower membrane is in good shape). I have decided to fill in the gap with thinset and put the new cement board on top of the floor instead of sliding it back in the 1/2 inch gap.Is that ok?