In doing the bathroom remodel (referenced on other posts), I'm re-tiling the shower and the floor (basically everything). In past similar projects (about 25 years ago), I used greenboard around the tub and 1/4" luan underlayment on top of the sub floor, for the floor tile. For this project, I'm going with cement board all around. I was at Menard's picking up supplies (don't judge me...) and grabbed 4 sheets of 1/2 inch "cement board" to get the floor started. When I got home and unloaded them, I realized that one sheet was Permaboard (it was lighter) and 3 sheets were Durock. Both claim to be 1/2", but without putting a micrometer on them, the Permaboard seems a tad thinner (maybe 1mm). I'm thinking to use the heavier stuff (the Durock) for the floor and saving the Permaboard for when I do the shower. However... are there any benefits of one over the other, especially for my applications? Also, for the floor, do I need to seal with anything before tiling? I'm assuming that I should use a floor leveling compound at the joints. Is there anything else I should do? Thanks!