Preparing Concrete Floor for Tile

Inspect the concrete surface for flooring adhesives. If you discover any adhesive, coat it with a layer of soy-based adhesive remover. Soy-based adhesive removers, unlike solvent-based products, are biodegradable and do not contain toxic chemicals. Brush the adhesive remover on the adhesive, following the manufacturer's instructions.

Leave the adhesive remover on the concrete for the dwell time recommended by the product manufacturer. Allow the product to thoroughly soften the adhesive.

Scrape off the softened adhesive gunk, using a floor scraper.

Rinse the concrete with warm water to dissolve the remaining gunk. Sweep the floor when it's dry, and then vacuum.

Examine the concrete subfloor for cracks. If you discover a crack, patch it with an epoxy filler. Slowly squeeze the filler along the length of the crack until all depressions are filled.

Smooth the wet epoxy with a trowel until the filler is completely flush with the concrete floor. Let the filler dry as advised by the manufacturer.

Brush two coats of polyurethane sealant on the dried epoxy filler to prevent water-vapor infiltration. Let each coat dry. Refer to the sealant manufacturer's directions for the appropriate drying time.

Coat the entire concrete subfloor with a single layer of crack-isolation membrane, using a long-handled roller brush. Crack isolation membrane prevents any cracking while the tile is being installed. Apply the membrane according to the manufacturer's directions. Let the membrane thoroughly dry.