How to Tile a Shower Over Plaster Walls

Coat the plaster in a thick coat of sealing primer, using your paint roller. Let it dry for 24 hours.

Measure across one wall of the shower and mark the middle. Make a vertical line from top to bottom with your pencil and level.

Spread thin-set mortar across the bottom half of the wall with your notched trowel.

Press the bottom course of tiles into place in the mortar, starting at the center line and building to the sides. Set spacers between the tiles, and below them, to separate the tiles from the shower floor.

Use a wet saw to cut the tiles for the two ends of the course, leaving a quarter of the space between the cut edges of the tiles and the side walls.

Set the second row in place above the first, again starting at the middle line and building to the sides.

Repeat, working your way up the wall row by row, cutting the end tiles as necessary. Use the wet saw to cut around the shower fixtures and other obstructions as needed. Cover the whole shower wall, and the adjoining walls. Cut around the shower fixtures with the tile saw as needed.

Let the mortar dry for 12 hours. Pull out the spacers.

Grout the tiles, using your grout float to spread the grout over them and press it in to the spaces between. Let it sit in the lines for 10 minutes. Wipe up the excess grout from the surface with a damp cloth.

Let the grout dry for 24 hours. Caulk the joints where the walls meet the floor and each other. Let the caulk dry for 24 hours.