How to Lay Porcelain Tile Over a Concrete Floor

Preparing the Concrete

• 1

  Pour a bottle of trisodium phosphate cleaner into a 5-gallon bucket and dilute it with water according to the package directions. Put on protective gloves because trisodium phosphate cleaner can be harsh. Dip your scrub brush into the cleaner and scrub the entire surface of the concrete. This cleaner will remove dirt and oil, giving the tile adhesive a stronger grip. Allow the cleaner to dry overnight. Rinse your bucket and let it dry as well.

• 2

  Go over the concrete surface with your level, looking for cracks and uneven spots. You cannot lay porcelain tile over cracks, which may grow, because the tile will crack eventually. Uneven spots can also cause tile to crack, especially if it is a high-traffic area.

• 3

  Mix a bucket of concrete patching compound and water, according to the compound package directions. Apply it with a putty knife to any dips or cracks in the floor. Let it dry overnight.

• 4

  Pour your concrete sealer into the paint tray. Apply a thin layer of the sealer to the entire floor using the roller brush. Start the application in the corner farthest from the door and work your way back toward the door. Let it dry according to the package directions. The sealer will keep moisture from weakening the tile adhesive.

Laying the Tile

• 5

  Mix a bucket of thin-set mortar according to the package directions. Generally, you add enough water to make a thick paste.

• 6

  Lay your first porcelain tile in the center of the floor. Apply a thin layer of the mortar to the back of the tile with a notched trowel and firmly press the tile into the concrete. Set the spacer next to the tile on any side. Apply thin-set to the next tile and lay it flush against the spacer. The spacer creates room in the floor for grout application. As you lay the tile, wipe each one with a damp cloth to remove any mortar before it dries.

• 7

  Repeat this process to install the tile on the entire floor, spacing between each tile. If you reach the walls and the tile does not fit, cut the tile with a rented diamond wet saw. The instructions will vary with the brand of saw you rent, so consult your home improvement store on exactly how to use the saw you obtain.

• 8

  Let the floor set for 24 hours.

Grouting the Tile

• 9

  Mix the grout according to the directions on the package.

• 10

  Apply the grout to the bottom of the grout float. Pull the grout float diagonally across the grout lines, filling the spaces as you go. Refill the grout float as needed.

• 11

  Hold the grout float so the sharp edge is all that touches the tile. Pull the edge across the entire surface of the floor, removing excess grout from the tile surface.

• 12

  Fill a bucket with warm water. Gently scrub the tile surface with a sponge dipped in the warm water, going in a circular motion. Run the warm sponge over the grout lines themselves, to smooth them. Let the grout harden for two days before you mop the floor.