I have vinyl tiles in my kitchen and I wanted to replace it with marble tiles. Do I have to remove the vinyl tiles first or can I just go over it with cement? Thanks.
You can cover the vinyl tiles, but you might end up with an uneven floor when you are done. Plus, like Doug said below, you will wind up with too much flexing for marble flooring, which might make it crack and fail much sooner than it should. You should probably bite the bullet, remove the tiles and start with a concrete slab.
Marble tiles require a very rigid support system. Or they will crack. The recommended deflection is L/720 whereas typical construction is rated at L/360 - twice as flexible. *Ceramic* tile is useable on an L/360 structure when a properly installed cement backer board is beneath it. Unless the floor of your kitchen is a concrete slab, I am willing to bet that it will deflect too much for a satisfactory marble tile installation without substantial beefing up of the floor structure. As for your original question, the answer is no, but you will need to lay cement backer board (Hardie backer, Durock, etc.) which will provide a proper surface for the thinset mortar to adhere to which will solve a small portion of the problem. But, the backer board won't do anything to solve the deflection problem along the floor joists, only between them. What those deflection limits mean is that for L/720, a 10 foot floor span will move 120/720=1/6 inch under maximum design loads. For the L/360 case, the movement is 1/3 inch or about 5/16.
