The easiest method is to apply a product called RedGard by Custom Products. It not only protects against cracks in the floor but also waterproofs it as well. You simply apply it to the floor with a roller or trowel, allow it to dry, and you have a seamless barrier. Here is a link to the product:
www.custombuildingproduc...
Michael Prachniak - Expert Tile and Stone Consultant and Writer, Owner - Tile Productions
Check out FAF''s tile section!
www.findanyfloor.com/tile/TileFloo...