Wipe the shower wall down with a tack cloth to remove all dust. Apply oil-based primer to the clean walls of the shower with a paintbrush. Let the primer dry for the time recommended on the packaging.
Hold the pieces of the Swanstone shower wall kit up to the walls of the shower space. If the pieces fit the space exactly, you don’t need to cut them. If they don’t fit the space, hold a piece of cardboard up to each wall, cutting it down to the size of each wall, using a utility knife. Use the cardboard pieces as guides to cut the Swanstone shower walls to size with a circular saw with a carbide blade.
Place the trimmed back wall panel along the back wall of the shower to check the fit. If the panel fits, apply several large pieces of double-sided masking tape to the back of the panel and stick it in place on the back wall. With the back panel in place, hold the left and right wall pieces up to the walls to make sure they fit, making additional cuts if necessary to trim them to the proper size.
Take the panels back down from the walls, including the back panel, and remove the tape from the panel. Measure up from the top of the shower base to any fixtures in the walls of the shower space, like the knob and shower head, and measure in from the sides of the walls and down from the top. Transfer these measurements onto the appropriate panel and use a hole saw to cut the holes for these fixtures.
Hold each panel up to the wall once you cut the fixture holes to ensure that the openings appear in the right places. When you have the correct fit, take the panels down again, remove any tape and clean the backs of the panels with denatured alcohol.
Cut the tip of a silicone caulk tube open to a roughly quarter-inch to half-inch diameter. Apply the silicone caulk to the walls of the shower in 1½-inch dollops every 8 inches along the surface. Lay the back panel against the wall, pressing it down into the silicone, then press the left and right panels into place on the walls.
Slide your hands all the way across and all the way down every wall panel to ensure that the panel touches all of the silicone caulk beads. Allow the Swanstone shower panels to dry on the walls for at least 48 hours prior to use.