Tiling a Concrete Block Shower Stall

Apply several coats of heavy duty block sealer to prevent moisture from seeping through the block. Allow the sealer to fully dry.

Use a tape measure and a chalk line to mark vertical lines on top of the sealer on all of the block walls on 16-inch centers. Install 2-by-4-inch pressure treated lumber vertically on the chalk lines with 3-inch concrete screws and a hammer drill. Lay the 2-by-4-inch lumber flat on the block walls when installing.

Measure the surface area of the block stall. Add 10 percent for overage and divide the number by 15. Round the number up and purchase sheets of 1/2-inch backerboard accordingly. Backerboard sheets measure 3 feet by 5 feet. Cut and attach 1/2-inch concrete backerboard to the 2-by-4-inch lumber with 2-inch backerboard screws until all the walls are covered. Start at the bottom of the wall with the backerboard sitting on the shower pan. Use screws every four inches on each 2-by-4-inch piece of lumber.

Cover all the seams on the adjoining pieces of backerboard with mesh joint tape, including the corners. Mix up enough thinset with water the consistency of peanut butter to cover the seams. Use a margin trowel to cover all of the seams evenly and smoothly. Leave as little of a hump as possible without uncovering the mesh joint tape. Allow it to dry overnight.

Mix thinset with the same consistency and use a notched trowel to spread it evenly on the backboard. Use tile spacers to hold the initial run of tile of the shower pan and install the first run of tile. Press the tile firmly into the thinset, and cut any tile pieces with a wet tile saw as needed. Install additional runs of tile using tile spacers to keep the tile evenly spaced. Do not install more than 4 feet of tile in a single setting. Lower tile pieces can start pushing off the wall if there is too much weight on them. Clean the tile free of any excess thinset and allow the tile to set up overnight. Finish each tier of tile daily until the entire stall is covered. Always clean excess thinset off the tile after each stage. Allow the final pieces to setup overnight.

Remove any tile spacers and clean the tile thoroughly. Mix enough grout and water to get the consistency of cake mix. Apply the grout into the grout lines with a rubber trowel. Push enough grout into the grout lines to ensure there are no gaps or spaces anywhere on the tile walls. Wipe off any excess grout with a damp sponge and clean water. Allow the grout to cure for 72 hours.

Use a clean sponge and seal the grout and the tile if you used any natural stone tile with stone and grout sealer. Allow the sealer to dry before using the shower.