Waterproofing
Sopro tanking kits and sealing tape for showers and wet rooms. Waterproof the substrate before tiling so the water never reaches the structure.
Waterproofing: what to buy and how to use it
Tiles and grout are not waterproof. Water passes through a grout joint given enough time, which is why a shower that was tiled straight onto plasterboard eventually shows up as a damp patch in the room behind it. Tanking puts a continuous waterproof membrane on the substrate before a single tile goes on.
The Sopro 5kg tanking kit covers a standard shower enclosure. The 20kg kit is sized for a full wet room, where the floor and the lower part of every wall need covering.
The joints are where tanking usually fails, not the open areas. Internal corners, the junction between wall and floor and the perimeter of the tray all move slightly and need waterproof sealing tape bedded into the membrane rather than relying on the liquid alone. Pipe penetrations need the same treatment.
Prime absorbent substrates first so the membrane bonds properly rather than drying out too fast, and leave the full curing time before tiling with a flexible adhesive.
Our bathroom tanking guide covers what actually needs tanking in a domestic bathroom, which is less than some suppliers suggest and more than most DIY jobs allow for.