For the bathroom floor use thinset spread with a 1/4" notched trowel as your "glue", then screw. In the shower, no cement board under your shower pan. You can use a preformed shower pan, 36" square is a very common size. Do a google search for "36" shower pan" and you should get quite a few hits. They come in different types of plastic, in Swanstone material, there might be a cast iron one out there too but I think Kohler's cast iron receptor is 36" by 48". If you want to build your own, Harry Dunbar has a nice pictorial showing how to do it with a conventional membrane here. There are also tole bases made by companies like Schluter. Noble, Wedi, etc, but they are shower "systems." You use their material for the base and walls. Here's a lengthy thread with lots of photos a DIY deck mud preslope covered with Kerdi, as well as a complete Kerdi shower. There are myriad ways to skin this cat. Mongo

I'm not going to comment on the differences between the two options, we never even considered a pan and it was never an issue with our contractor. In addition to having to build it in, you have to allow a couple of days for the concrete to cure, so I'm sure it takes longer. It makes sense that he wants to take the method of least resistence "and get it done to be done with it" because time is money and the quicker he can finish your job, the quicker he can move on to the next. But that doesn't mean that you should be asked to compromise what you'd prefer to do just because it will benefit your contractor. Get additional quotes and stick to what you either vision or can afford to do. Also, when my GC was tiling our master bath, I ran into a similar situation with our niche. Bill told me something that really put things into perspective and changed my whole approach to the project. He said, "He who holds the golden egg is the boss" In other words, it's your project, you're paying the bill, so you make the call. If it's not a job he wants to do, find someone else you feel comfortable with who will.

TorontoTim, I suggested the vapor barrier behind the cbu as an alternative method to Kerdi/Red Guard/Hydorban/ect only because, at least in my area, it is difficult to find a lot of tile guys who work with these methods - even Red Guard which is easily available at Home Depot. They may be set in their own ways, laziness to learn new methods , or time. You would be surprised how many builders are installing tile on straight cbu - and the reason they are using cbu verus greenboard is the relatively new code. Ladoladi, I suggest you educate yourself with the various methods of building a shower by searching this forum. Using a vapor barrier behind cement board is an accepted practice. The cement board does absorb moisture through the grout and takes longer to dry out versus putting a moisture barrier on top of the cement board. And the moisture barrier on top (Kerdi, Hydroban, Red Guard, etc) is the best method. If you go with a cultured marble shower, ensure that the framing and the marble slabs/pan are level, flat, plumb, straight, "true", etc. Make sure the shower components fit well together and the corners overlap well. Cultured marble is made by hand and manufacture quality and installation are dependent upon the individual shop. You will have to maintain the caulk on the seams on a regular basis (especially after seasonal temperature changes) because that is the only thing keeping the water from getting back behind the walls. The pan does have a lip. A good shop should install the cultured marble on cement board with a vapor barrier behind that. If your marble is light colored, you can paint the cement board. I do not know if the cultured marble can be installed on a moisture barrier that has been applied on top of the cement board. That would be a better way if it can be done - but so many of the cultured marble shops still install cultured marble on greenboard type drywall. (I had the cultured marble shower from hey installed by my home builder and learned all the wrong ways to build them.) Good luck with whatever you decide. This post was edited by Anna_in_TX on Tue, Dec 31, 13 at 21:49

I agree, they messed up. However, to fix this would require ripping out the entire thing and this small remodel project has already spanned over three months. We’re ready to be done with the whole experience, not drag it out for another three months. We’ve already negotiated discounts to the final project cost based on issues with the shower, so while I’m not 100% happy with the shower, it is something that we can live with. It’s functional and we realize that our space was challenging to work with. The pan is solid everywhere except this one corner and the water drains properly. The entire shower enclosure was a sloppy install from a cosmetic standpoint, there is no way that I would want the same plumber to redo it. We are very happy with how the rest of the bathroom turned out, the shower is the only problematic area. It’s annoying but not worth the hassle of forcing the contractor to rip it all out and start over, especially if we can level the threshold enough to install the shower door. All of the weight is supported by the walls and crossbar, I just need a level surface to rest the skinny little threshold piece on top of to guide the doors and have them open/close properly.