Here's a tile tip from Minneapolis tile contractor TJ Roemer of Creative Tile Works: If you are installing a tile floor, the most durable underlayment is a floating floor. A floating floor is a layer of paper membrane, metal lath, and a layer of concrete floor mix above the wooden floor board. The floating floor supports the tile independent of the wooden subfloor. When the house shifts, expands, or contracts, since the tile floor is supported by the floating floor, the movement will not effect the tile or grout.