Create a Plan for Tiles to Follow

• 1). Mark three tile spaces plus 1/4 inch from the longest wall. Begin by measuring three tile spaces from each end of the longest wall, and then add a 1/4-inch space from the wall for an expansion gap. Mark both points with a pencil.
  
  
• 2). Snap a chalk line between the two marks.
  
  
• 3). Mark three tile spaces plus 1/4 inch from the adjacent wall. Follow the procedure you used previously.
  
  
• 4). Snap a chalk line between those two points.
  
  
• 5). Check that the lines are square. Measure one chalk line 3 feet from the meeting point. Then measure the chalk line diagonal to the pencil mark 4 feet from the meeting point. Measure between each pencil mark. If the measurement is 5 feet, you have a 90-degree angle, thus square lines.
  
  
• 6). Lay dry tiles and tile spacers. Follow the chalk lines beginning 1/4 inch from the wall. This will give you a pattern to follow when you are ready to adhere the tiles to the subfloor.
  
  
• 7). Mark tiles that need to be cut.
  
  
• 8). Remove the dry-laid tiles and tile spacers.
  
  

Lay the Tiles

• 1). Check that all wires of the heated flooring are as flat to the floor as possible. This will prevent snagging.
  
  
• 2). Mix thin-set mortar. Attach a mortar mixing pallet to a drill and mix the thin-set mortar at a slow speed. Mix small batches at a time to prevent hardening.
  
  
• 3). Spread thin-set mortar in a 5- to 10-foot square on the electrically heated floor. Use the back of a notched trowel for this. Press the mortar into the mat and through to the concrete subfloor, careful not to damage the electric heating cables.
  
  
• 4). Run the notched side of the trowel at a 45-degree angle carefully over the mortared area.
  
  
• 5). Lay the first tile. After pressing it firmly into the mortar, lift it to check for even coverage. If the tile's back isn't covered with mortar or the mortar feels dry, then scrape off the mortar and reapply. Repeat this procedure randomly throughout the project.
  
  
• 6). Lay the other tiles. Butt their edges together. Wiggle tiles back and forth and place tile spacers.
  
  
• 7). Let the mortar dry for the time recommended by the mortar's manufacturer.
  
  

Grout the Tiles

• 1). Apply grout. Begin the process by removing the tile spacers. Mix the grout with water in a 5-gallon bucket following the instructions on the back of the grout packaging. Hold the rubber grout float at a shallow angle, and fill the grout lines by sweeping the grout in an arching motion. Work in small areas, and remove excess grout by holding the grout float at a sharp angle and running it slantwise across the tiles.
  
  
• 2). Remove all excess grout. Wipe the tiles with a moist sponge to remove grout deposits. Wring out the sponge often, and work quickly.
  
  
• 3). Polish the tiles with cheese cloth.
  
  
• 4). Follow the manufacturer's instructions on how to connect the thermostat wire and power lead to the thermostat.
  
  
• 5). Cure the grout for three days after grouting. Do this by misting the grout with water twice each day.
  
  
• 6). Clean the floor with a tile-and-grout cleaner. Then rinse the floor completely and let it dry.
  
  
• 7). Apply a penetrating grout sealer or a tile-and-grout sealer, depending on your tile selection.