Before starting work, the bathroom itself and all pipes are required to be covered with polymer film or construction tape, which will help to avoid all kinds of damage. You will also need to carefully prepare the walls before laying tiles. The preparation will depend on what tiles will be planted on. In that case. When a cement mortar is used, the wall should be slightly rough. If the tile is attached using glue, the wall should be perfectly smooth. The existing gaps are closed with a tape made of fiberglass.