Installing Electric Radiant Heat Under The Floor

Using electric radiant heat underneath stone or tile floors is an energy-efficient way of providing comfortable heat an affordable price. In addition, electric radiator heat works very well as supplemental heating in bathrooms and entryways. Installing electric radiant heat under tile or stone floors is relatively simple, and involves the use of electric radiant heat mats.

Tools and Materials Needed:

  • Scissors
  • Trowel
  • Mortar Mix
  • Multimeter or Continuity Tester
  • Tile Tools
  • Cement screws or nails

Step 1– Prepare the Floor

Install tile backer board on the floor, fastening it to the existing subfloor with thin-set mortar and cement board screws or cement nails.

Step 2– Sketch the Room

Create a scale drawing of bathroom or kitchen floor; be sure to include any sink counter, vanity and/or tub and toilet locations (as the case may be for your kitchen or bathroom).

Step 3– Purchase the Radiant Heat Mats

Next, take the drawing to the hardware store so you can buy the proper sized mat or combination of radiant heat mats. Things to keep in mind when determining the size of the mat(s)

1) You will need to install the mat up to the edge of where counters or vanities will be, but not under it; this causes too much heat buildup;
2) Make sure that the mat is 4 inches away from walls, showers and tubs;
3) The radiant heat mat should be at least 4 inches away from the toilet bowl wax ring;
4) Never allow the heating cables to overlap or touch. Try to keep them at least 2 inches apart;
5) Don’t leave large gaps or spaces between the mats.

Step 4– Test the Wiring

Check the heating mat wiring with a multi-meter or continuity tester, to make sure it wasn’t damaged during the manufacturing or shipping process.

Step 5– Install an Outlet

Install an electrical outlet box approximately 5 – 6 feet up along the wall nearest to the area where the wiring leads running from the mat will be terminated. Install new wiring to the outlet box that runs from the circuit breaker panel or - if the radiant heating mat is particularly small - from the closest outlet (you can do this yourself, but it is probably better that a licensed electrician hooks up the mats to a circuit breaker box).

Step 6– Measuring for Tiles
Draw layout lines for the tiles on the floor surface. Try to use tiles that are at least 6 inches squared - each tile will cover two or more sections of the heating cable. Do not use tiles smaller than this when installing electric radiant heating mats, because the floor may develop peaks and valley type ripples.

Step 7– Placing the Radiant Heat Mats

Place the mat onto the floor; then secure it the cement board with double-faced tape. You can also use hot-melt glue sticks and a glue gun add additional adhesive to the mat. Make sure there are no large lumps or loose edges

Step 8– Run Wiring for the Thermostat

Install conduit from the floor to the outlet box, and then run the thermostat wires in to the outlet box. Make sure to securely fasten the conduit to the wall.

Step 9– Lay the Tile

Install the tile floor over the electric radiant heating mats or have a floor installer do it.

Step 10– Connect the Thermostat

Connect the power lead wires and thermostat wire (from the heating mats) to the thermostat, following the manufacturer's instructions.
That’s it’ you’re finished now enjoy the added warmth to your bathroom or kitchen.