When Laying Tiles on a Plywood Base, A Large Role Will Play The Frame. When Using Such Bases, Moisture -sistant Plywood Is Most Offten Used. The Strongger the Frame, The More Likely it is that it canthastand The Lining of in a Floor Tile, Which Quite Heavy. IF the Surface is not Stable Enough and Bends, The Tile Will Just Fly Out of Fastens, Crak, Break, So the Thickness of the Base From Plywood Shoup Reach About 28 Mm MM.