Clean the shower floor thoroughly with a damp cloth. Avoid using chemical cleaners as they may interfere with the adhesion of the bathroom silicone caulk. Clean the sides and the bottom of the stone shower seat with a damp cloth. Allow the shower seat and shower floor to dry completely before installing the pre-made stone shower seat.
Place the shower seat upside down on the floor so the bottom is facing you. Depending on the size of your pre-made shower seat, it may be necessary to have a helper to move the seat.
Apply a 1/2-inch bead of bathroom silicone caulk to the sides and bottom of the seat with a caulk gun. Run a bead around the perimeter of each side and the bottom, 2 inches from the edge. Run another bead in between the perimeter bead in an “S” pattern.
Pick up the stone shower seat, with the assistance of your helper, and set it into the corner of the shower with the base of the seat sitting firmly on the shower floor. Press the stone shower seat into place, ensuring good adhesion of the caulk between the shower floor, walls and seat.
Take the silicone caulk out of the caulk gun and insert a tube of grout. Apply a bead of grout between the seams where the stone shower seat meets the shower wall and floor. Wipe off excess grout with a damp sponge.
Allow the caulk and grout to cure for 24 hours before using the shower.