I have been flirting with the idea of replacing tile floors in my bathrooms and adding in-floor heat to them as well. What I am wondering is, what would the difference in height be with the in-floor added? I don't want a step up into my bathroom from the hallway. Right now there is just typical underlayment over the subfloor. As far as I know the only way to do it is to have a mortar bed under the tile with the heating elements contained in it. Is there something else that might work better? Thanks much.