Hello all
I am preparing to remodel my bathroom in a 100+ year old house. Our unfinished basement gives us a clear view of the under sides of the floor. Under the entire bathroom is a poured concrete floor. I pulled up one of the existing tiles which revealed the subfloor of the bathroom is indeed cement. (it is approximately 4 inches thick? Guessing)

My question is
1. does anyone know why there would be cement covering the whole bathroom floor?
2. I am going to install infloor electric heat mats, and then tile. Can this be done directly on top of this cement floor (with the appropriate layer of thin set)

3 is there any reason to remove this? (this would be a huge job for a little bathroom)

Thanks in advance for any insight into this.

I don't think that you would need to remove the cement floor. But, you may need to modify it somewhat.

There is some information on the following site that, I thnk, might address some of your concerns.

Electric Floor Warming Systems (http://www.flooringguide.com/how-to/related/rp001.php3)