Looking at the list of insulation factors that Yanche posted [thanks John], I'm surprised by the fairly high factor for ceramic tile, .30. And also surprised by the relatively low factors for wood flooring. .50 or so.
I would have thought that ceramic would be near to 0, since it is cemented to the concrete floor,, and is solid minerals.. like concrete.. But wood is full of air spaces, and does provide a fair amount of insulation factor... Maybe it's the fact that it is dense wood, not soft pine...
Anyway,, when I'm standing on my heated ceramic floor in front of the bathroom sink and mirror,, I shuffle around till I find the warmest spot to stand on,, a warm floor is an amazing luxury,, especially when you get out of the shower..