I will be installing some new 12x12 tiles in two bathrooms approx 25 sq/ft each. When I pulled up the old tiles, there was no thin set that had made contact with them so the removal was very easy. Now, the thin set on the floor is a different story. I have been chipping away at it by hand in one bathroom to get to the cement floor below and it has been a bugger to get off. Before I attempt to continue this process in the second bathroom, I would like to know if it is absolutely required to do so if it is well adhered to the cement underneath?
(It's my hope, obviously, that I can tile over the old thin set as long as it is level and firmly attached.)
EDIT: My subfloor is a concrete slab with the thin set on it. It must be chipped away to remove vs. cut and replace sub floor.