If you are going to spend the time and expense to lay down tile, spend the extra money to make sure the floor is nice a warm. Laying floor heating cable is not that hard of a job and the awards of a warm floor on your bare feet is well worth the extra cost. If you like to tackle home projects and are a do-it-yourself home project person you will have no problem laying this wire under your tile floor. I took on this project a year ago and have been enjoying the warm bathroom floors.

For significant saving I would suggest just buying your floor heating wire and not bothering with pre-weaved floor heating mats. This wire can be purchased at a great discount. The wire I purchased is available on eBay. Several sites presently are selling this cable including this store.

In deciding on a cable to purchase, you definitely want a cable that is UL listed. This means that the UL laboratory has certified that your cable is safe to use. I would suggest going with the cable that contains two twisted pairs. This configuration eliminates electro-magnetic fields (EMF). Also the small diameter cable is nice in that it reduces the labor in laying the tile on top of it

When purchasing this wire it is important to remember that the cable cannot be cut. Thus you need to figure out the square footage you wish to heat, prior to purchasing the cable. Website typically list their cable by length and the matching square footage.

My project below will only cover laying out the floor heating cable. For more information on laying tile the "Home Depot – Home Improvement 1-2-3" book is a very good reference.

Step 1 - Cover the floor with backerbaord. You do not want the cable on a bare wood floor as it is design to be incased in mortar. Backer board also helps to keep the heat in the tile floor and not in the space under the floor.

Step 2 – You will need to purchase and install a floor thermostat. These are available on eBay. You will need to run a 120 V (15 or 20 amp) GFCI (Ground Fault Circuit Interrupter) circuit to supply the power for your floor heating cable. I do not wish to go into too many details in the area as local electrical codes vary. Unless you understand electricity I would suggest you contact a local electrician to do your electrical work. Once you know where for floor heating thermostat and electrical supply cable will be located in the wall, cut a small hole at the base of the wall, below the line of the trim board, and use this location to start your layout of the heating wire.

Step 3a – Decide how you are going to weave the cable on the floor. You can use nails or screws as anchor points to wave your cable around the room.

Step 3b- Start weaving your cable around the nails. The good part about using nails is if you get the end of your cable and you are short or have extra cable available, you can easily unwind the cable, modify your layout slightly, and then weave the cable again. I redesigned my layout a couple of time before I was happy with the coverage and used all the cable (remember you can not cut this cable).

Step 3c- When laying out the cable, place the cables about 3 inches apart. This will give you the best heating coverage for an indoor floor. The square footage coverage is typically based on 3 inch spacing. If the floor is near an outdoor wall or on a cement pad you may wish to decrease the spacing to increase the amount of heat in those situations. Also do not overlap the cables or allow them to get too close as this will cause the cable to overheat and it will fail prematurely.

Step 4 – Once you are happy with the layout, use masking tape to secure the cable to the floor. Make sure the cables are nice a strait and maintain your 3 inch spacing. You can now remove the nails.

Step 5 – Prior to laying down the tile, I would suggest making sure your cable is not damaged. You will need to strip the insulation off the cable and twist the wires together at one end. At the other end use a hand held meter to measure the cable resistance. The resistance should be less than 20 ohms. Check your wire (ohms/foot) to calculate an exact value.

Step 6a – Lay out your tile.

Step 6b – Apply the motor liberally over the cables. You need to add a thicker layer to make sure the wire is covered completely. If the layer is too thin, you will be transferring the floor weight on top of your wire. Also be very careful not to cut your heating wire.

Step 6c – Lay down your tiles. I did not find that the process of laying down the mortar was any harder than laying tile without the heating wire. You just need to be a little extra careful that you do not cut the cable. You also need to try to keep from moving a cable as much as possible. You want to maintain your wire spacing.

Step 7- Connect your cable to the leads coming from your floor thermostat. As the floor wire tends to be a fairly small gauged wire, I striped off an extra long piece of insulation, doubled the wire back on its self, and solder the ends to add some extra thickness to the wire end. This made crimping the wire to the electric wire much easier. I then covered this connection with heat shrink insulation. Again if you are not familiar with electrical wiring, a local electrician can easily perform this connection.

Step 8 – Complete your connections to the floor heating thermostat. These thermostats sense the temperature of the floor so you will need to run the thermocouple wires from the thermostat under the tile floor. Place the end of the thermocouple wire between two floor heating cables. Do not overlap the thermostat wire and the floor heating cable.

Step 9 - Finish laying the remaining cables.

Step 10 – Grout in the tile, clean and seal the tile floor, and start enjoying you new warm tile floor. I found that setting the floor temperature to 85 deg F is just about right. My floor thermostat has a timer. It takes about 2 hours to heat the floor from 65 deg F to 85 deg F.