yea, like plank said, you have to tear it all out, check the sub flooring, make sure its all ok and not rotting out, then line the floor, run the tubes, have access for the connection for the tubes, then lay all new tile. in my house the tile was a bitch because it takes a long time to get to temp. so make sure you do a little research on the thickness of the tile and heat transmittance. once its all said and done it not bad at all, just a pain in the ass. good for bathrooms and kitchens. be prepared for your bills to climb a little too.