How to Install Floor Heating Systems Under Ceramic Tile

Heat cables in thin-set.

Ceramic tile, like all masonry products is cool to the touch unless it encounters direct sunlight or a heat source. While heating systems are common beneath hardwood and laminate flooring, ceramic tile is unique because it requires a base of cement before the tile is applied. With the correct products, a skilled do-it-yourselfer can install a radiant heating system underneath tile.

Difficulty:

Challenging

Instructions

Things You'll Need

• Finished sub-floor
• Thin-set
• Notched trowel
• Backer board
• Heat cable
• Ceramic tile
• Grout
• Thermostat
• Sensor

1. Prepare your sub-floor approximately 1½ inch lower than you want the surface of your finished tile floor. The layers of thin-set and backer board will raise the level.

2. Apply a thin even layer of thin-set to the sub-floor by pouring out a small amount and using the notched trowel to spread it approximately 3/8-inch thick. Thin-set is a blend of finely ground cement and sand with a water retention compound designed to offer excellent strength in thin applications.

3. Make sure your entire floor has an even coat of thin-set. After toweling, it will appear to have many tiny lines running through it. The key is to make the thin-set application is as level as possible. Allow it to dry completely and sand down any raised areas.

4. Cut and fit the backer board on top of the thin-set layer. Secure with screws every 16 inches. Leave a 1/8-inch space between the backer board and the edge of the wall.

5. Install the heat cable by laying the end that attaches to the thermostat and power source at the edge of the backerboard and allowing it to pass into the framing stud on the side of the wall where you have cut notches, specifically for the cable. Lay the radiant heating cable in an even pattern of rows across the floor, making three-inch turns and the ends of the rows so that every three inches of floor has a cable.

6. Install the sensor beside the heat cable so that it extends at least 2-feet into the flooring space and is equally between two rows of cable. It should lie flat along the backer board just as the heat cable does. The sensor cable should extend beside the heat cable through the notches.

7. Apply one more layer of thin-set over the backer board, carefully covering the heat cables. Cover the cables completely with the thin-set. Again, use the notched trowel on the surface and keep it level.

8. Grout the ceramic tile, following the instructions on the bag of grout and wipe any excess grout from the tile’s surface quickly before it dries.

9. Hook up the thermostat and power source to your radiant heating cables inside the framed wall and install the thermostat cover on the finished wall for convenience. All you have to do is adjust the thermostat and the floor will respond with radiating warmth.

Tips & Warnings

• You can install other heating systems under tile. A heat cable, embedded in a fiberglass mesh, lies on the floor in place of winding the cable. Another method uses pex tubing and attaches to a hot water tank where a pump re-circulates hot water throughout the floor. All the methods utilize thin-set so they are permanent once installed.