Step 1: Cut and Place the Cement Board

Cut the cement board to size. Place the cement board on the subfloor.

Use a screw gun to drive screws into the cement board every 8".

Step 2: Connect the Wires

Set an ohmmeter. Connect the wires from the floor mat to sensors. The reading should be within 5 percent to 10 percent of the factory reading (28).

Step 3: Dry Fit the Mat

Move to critical areas where heat is desired. Mark the outside of the mat with a pencil line to use as a guide so the thinset doesn't extend beyond the mat.

Step 4: Mix and Apply Thinset

Mix the thinset, and add the thinset mix to water. Mix until it's of soupy consistency.

Scoop the thinset out of the bucket with a trowel. Spread the thinset with a notched trowel in pre-marked areas.

Step 5: Lay the Mat and Apply the Probe

Lay the mat over the thinset. Smooth it out with rubber float. Make sure to apply enough pressure to secure the mat to the floor (Image 1).

Apply the probe 1'-2' off the end of the mat, near the electrical connection, between two hot wires on the mat.

Tape down the probe with electrical tape (Image 2).

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    Image 1

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    Image 2

Step 6: Lay the Tiles

Dry fit the floor tile. Lay out the tiles to determine how to cut them. Keep full tiles in the most visible areas. Measure one tile width plus 1/4" for the first row.

Snap a line as the guide.

Apply thinset to the back of each and lay the tiles on the mat.