Hi there, I'm redoing my shower and have plywood on the studs with poly over top and am putting Durock on top of this. Next step is to apply mortar and apply tiles. My question is which side of the durock should face out, that is, which side will I tile against? The smooth or the rough?

Thx.

Rough side is intended for thinset installations and smooth side is intended for mastic installations. Since this is a wet area, modified thinset, from a bag is what you should be using, so rough side out. Truth be told, your thinset will stick to either side, though.

Why the plywood?

Just as Brian said. But what is the sheet of plywood doing there, is it to space the wall out? That is against the rules, but since you've covered it with poly you should be fine.

Jaz

The plywood was to bring the wall flush with the lip of the tub as there was about 3/8" difference, and the tile would not have finished where I needed it to, in order to have the tiles come down in front of the lip.