I'm helping a friend who is determined to use the HD Trafficmaster Ceramica vinyl tiles, in spite of my encouragement to go with regular ceramic tile. These are peel and stick and are groutable. We've figured out most of the installation issues, but are stymied on how to install the Hardibacker he's got. He's using 1/2" Hardibacker on top of 3/4" OSB subflooring. The question is how should the Hardibacker be installed? According to the directions for regular tile...a bed of thinset, taped/thinset joints, then nailed...or should we follow the directions for vinyl tile...no thinset, just nails/screws and butted together at the joints? Since these are closer to vinyl then ceramic, should the Hardibacker be put in smooth side up rather than the embossed grid side up?