Step 2 · Create Plumbing Access
To access the valve, you must create an opening in the wall. Since we assume there is no access panel, you'll need to cut through the tiled shower wall. First, use a stud finder to locate the studs on either side of the existing valve. Using a pencil and a level, mark a rectangular opening that is large enough to comfortably work within (e.g., 12x12 inches). Put on a dust mask. Use an angle grinder equipped with a diamond blade to carefully and slowly cut along your marked lines through the tile and backer board. Remove the cut-out section.