I am having porcelain tile installed in my new kitchen (moved kitchen to dining room). All the cabinets and appliances will be installed on top of this tile. The new kitchen is on the second floor of my house over my garage and will have granite countertops and a heavy island. The wooden joists underneath the floor are 1 foot apart and are covered with plywood.

Years back (8-10 years or so) when I had granite floor tile installed in my adjoining living room (also on the second floor and over my garage), my tile installer made a big deal about putting a cement board underlayment down, as he claimed that it would protect against cracks. So far, I have had no cracks.

My GC for my new kitchen project does not want to use cement board. I am not sure of the name of what he wants to use, but he described it as a grid. I think he may be referring to Ditra.

What is the best product to use underneath porcelain tile with heavy cabinets/countertops involved? I do not entirely trust my GC, sadly.