Setting Countertop Tile Over Cultured Marble

Check the stability of the cultured marble installation. The easiest way is to try to separate the visible edges. If the sheets appear to be stuck well on the exterior, start checking the surface for bubbles or areas where the laminate might be coming apart or loose. Cut out any loose sections or bubbles with a utility knife, and fill in these spots with thin-set mortar later.

Prepare the cultured marble surface for the thin-set mortar. Cultured marble is not a recommended substrate and is too slick for thin-set normally, so you have to sand down the surface. Firmly hold a belt sander in both hands, pull the trigger and run the sander over the entire surface until it has been completely roughed up so the thin-set mortar will stick.

Scratch-coat the surface of the cultured marble with a thin layer of thin-set mortar. Use the flat side of the trowel to scrape the thin-set over the top of the cultured marble countertop, and apply pressure so the thin-set completely works its way down into the surface of the laminate, bonding with the sanded surface. Let it dry for 24 hours.

Install your tile as you would normally. Run full tile against the front edge of the countertop, and work your way back to the backsplash, installing a cut along the back wall. Spread the thin-set mortar with the notched trowel and push each piece of individual tile into the thin-set. Use tile spacers between the tiles to create the grout joints. Let the top dry for at least 24 hours before grouting.

Grout the installation. Apply pressure with a grout float to force the grout into the joints. Wait at least 20 minutes before washing the grout from the surface of the tile and smoothing the joints. Dampen a sponge in a bucket of water, wipe the grout lightly in a circular motion across the joints too smooth them, rinse the sponge and, when it is clean, drag it lightly across the joint diagonally to completely clean the surface. Repeat this process until the top is finished.