First time poster here. This looks like a good forum. I did browse through some threads before deciding to post. Apologize if this appears similar to previous threads.
We are remodeling our upstairs bathroom. At this point, I am prepping the floor for ceramic tile. The existing floor consisted of sheet linoleum glued like crazy to 5/8" plywood which is over top of 1/2" plywood subfloor (nailed to the floor joists). In order to remove the linoleum, I ended up ripping out the 5/8" plywood. Now I am in the process of putting down fresh 5/8" plytanium over the 1/2" plywood which orients the 5/8" perpendicular to the joists. Should I be screwing and nailing the 5/8" down? I have 1/4" hardibacker that will be laid in thinset and screwed down over top of the 5/8". I have already started on the nailing of the 5/8" following the nailing that was done on the previous 5/8". Do I need to be hitting the joists on the 5/8" and what is the proper fastening schedule?