Waterproofing behind tile is a one and done opportunity. It cannot be repaired, replaced, or altered in any way once the tile is installed. Therefore, as builders we should take it very seriously. Aarow Building switched to using Schluter’s Kerdi membrane some 14 years ago and hasn’t seen a need for anything else since then. With a systems approach from the manufacturer where you can rely on one warranty for your entire shower, there is no need to worry. Eliminating the cement board and roll on products has been a blessing for our backs and minds.