I just had my shower rebuilt by a contractor. It's done in 18" travertine tiles. The tiling was finished about a month ago but we haven't used the shower yet (more work in other parts of the bathroom are still underway). It has recently come to my attention that shower niches are notorious for leaking and that they need to be properly waterproofed. I would like to ask my contractor if he did this but I don't know what questions to ask. I've read that the bottom of the niche should be sloped to promoted drainage (which it is) and that inside the niche (behind the tile I guess) there should be some sort of sealing material like RedGard.
Is there anything else I should ask about?
Thanks, Dave