The original floor was 5/8 ply on top of 3/4 ply. We had the 5/8 ply removed since it was not glued and had the Advantech 3/4 put on top of the remaining 3/4. The Advantech supported install is to screw the base floor to joists put layer of roof felt then screw the top layer to the bottom only, not through to the joists. Floor is rock solid now.
