HI HOW ARE YOU? MOST OF THE TIME IT ALL DEPENDS ON THEPROJECT YOU ARE DOING. IF YOUR JUST REPLACING ONE TILE THEN YOU CAN JUST USE A CHISEL AND, SCAPE IT. IF YOUR REPLACING THE WHOLE FLOOR YOU WANNA GO OVER TOP OF IT WITH A 1/4 INCH PIECE OF LAUN OR, IF YOUR DOING TILE THEN YOU WANNA USE CEMENT WONDER BOARD ON TOP. EMAIL ME IF YOU NEED HELP OR, HAVE A QUESTION AND ID BE GLAD TO HELP YOU. I DO ALL OF MY OWN WORK.LET ME KNOW WHAT YOUR PROJECT IS.