Glue it down with Bonsal 2001 mastis, one sheet at a time. Nail it with 1&1/2inch roofing tacks. Do the nailing in a 6 inch pattern. You can use any mastis, just as long as it strong. you also can use liquid nail. But if you use this it will take 1 tube per 1 and 1/2 peaces of durock Of coures the durock being 3x5 sheet. you could screw it down, but its not nessasary. Nailing is find. It will hold. If your going by National Tile code book you will have to put it down with Flex-bond, with acrilic additive. I might have spelled acrilic wrong but the people you buy it from can help you. Main thing is to Glue it down and Nail it in a six inch pattern.