I've got every thing else done (original builder didn't seal the edges of the marble, it crumbled and molded behind)... I just need to put the new marble trim up, the rest of the shower is tiled in. The backing for the marble is DuraRock (as was the rest of the shower), what prep work (vapor shield, leveling?) do I need to do, and what do I use for an adhesive (liquid nails tub and surround?) . I know I have to clean the marble (rubbing alcohol) is there any other prep I have to do too the marble? Also the marble should create a bit of a lip inside and out of the shower wall do I just use silicone to seal it off?



Thanks,
Adriaen.

Do not use liquid nails for marble. It may work on a 2x4 but marble needs a modifed thinset, ask at your tile store. Not any silicone can be used, look for something like Daps mildew proof silicone. It has a built in mildewcide. You are sure you goit out all of the old mildew, right?

Definitely got the mildew we ripped out the shower Completely studs and all. Where the tile meets the durarock it isn't perfectly level. I could grind the edge down to level it, is there a better (easier) way?

By level do you also mean straight? It looks like a vertical line that may be out of plumb. Not many ways around correctly a crooked tile line. I'd use an angle grinder with a masonry wheel. Buy or rent one, I've seen them at ACE and other stores for $20 but they probably won't have a lifetime guarantee.