Rich256 wrote:
Go to Home Depot if possible and take their class.

Not Recommended! We had decided to try and do our bathroom floor and
went and took a Home Depot Class. Home Depot advised that if the
Bathroom Floor was "Level" and did not "give" then you could lay the
tile right on the plywood without using a backerboard.

Luckily we found out before starting the job that Home Depot didn't
know their ass from a hole in the ground.

NIK