I can't speak for warmboard, but we used electric wires from Warming Systems (warmingsystems.com). You can either tape the wire directly to the floor or buy thin mats that have the wire already embedded in it.

We are in the midst of a total gut and renovation project. Our entire home will be heated with radiant floor heat. Do you have room for a product like warmboard that goes on top of the existing floor? If you're raising the level of the floor, your exterior doors may not work. It appears to be much more economical to use staple up under the floor between the joists, if you have access from below. We were not able to access from below, so chose to create are own version of the Watts Sub Ray system. So far, the istallation has been problem free, though it is not operating yet. Let us know what you end up doing.

I too am worried about the exterior doors. I am meeting the contractor this week to go over options. I may just not do radiant close to the doors and put a slight donward angle to the doors. Not sure how that would look though. I prefer not to do the staple up as I have heard that it isnt that efficient. Is the watts sub ray system electric or hot water? Please let me know what you think once you are up and running.

Sorry for the delay. I've been off the internet for a few days. The Sub Ray system is hydronic (water). We chose to install 1/2" tubing so it takes 3/4" + the thickness of your new floor coverings to clear the exterior doors. You can use 3/8" tubing, which knocks a 1/4" off the height.

We just installed the tubing into the floor system and will hopefully be operational by the end of February. I'll post again when there is something to say.

Maybe for your exterior doors do a small section of tile and still heat the tile? Exterior doors are subject to more weather, water, wear and temperature fluctuations, and I recall someone smarter than me suggested putting tile there and heating it, making it an excellent area to leave wet and snowy footwear. ;-)

Can anyone tell me a ballpark cost of what radiant flooring is costing everyone and the size of the room. In the planning phase and we are trying to see if it is economically feasible.