The joints between tiles and panels used in a shower are not waterproof, which is why you need a waterproofing system under the wall covering, but especially on the floor to prevent the possible passage of water between the joints cause structural damage.This is more so for floor-level showers where the old ceramic shower tray is replaced by tiles, creating continuity between the bathroom floor with the shower, without steps and without structural obstacles, but with the presence of leaks.In this instance, waterproof membrrane such as Durabase WP is recommnded to act as a barrier of water.