Clumsy, my patuty!! WOW!! Where do you live??? Can I come out and tile your bathroom??? :-) In all seriousness, that's going to be one sweet masterpiece to put together! Before I get to your questions, though I do see one problem. It's going to be tough to run the chair rail through the shower and have any kind of glass enclosure. Not impossible, but tough. You would have to work together with your glass guy to figure out EXACTLY where the glass would go, so you could leave notches in the chair rail. I can guarantee you-- they're not going to notch the glass for you. :-) Now, on to the questions: #1-6) What you have drawn is excellent. With reference to the subway tile, no, the corner pieces do not need to be mitered. What you can do is cut the pieces, but then turn the cut edge into the field, and use the "factory" edge as the bullnose. Now, I said they don't NEED to be mitered. However, if you'd PREFER to miter them, there's no reason why you couldn't. It's not like it's ceramic where you'd have to worry about a sharp edge. As for the chair rail and liner, you're right. Those WOULD have to be mitered. The biggest tip I could give you about mitering the chair rail would be to have a piece of 2x4 handy with a 45 degree mitered end on it. You can place the mitered side of the 2x4 against the wet saw tray table's edge, and that'll give you the correct angle, and the thickness of the 2x4 will give you something to make sure you're standing the chair rail up straight while you cut it. If you decide that you want to miter all the outside corner tiles, the only advice I can give you is leave a little "meat" on the edge. You don't want to take the miter all the way to the face of the tile. If you do, you'll end up with an extremely ragged edge. Leave 1/16" of meat or so on the front edge. The finished miter will still look just as tight, and it'll be 100% stronger. #7) Don't worry about continuing the cuts. Atleast not on the subway tiles. For the most part, the ONLY time you really need to worry about it is when you use a diagonal layout. With running bond (the brick joint pattern), there's no need to continue it. Take each wall individually. Now, the best thing is to center the walls. However, sometimes that gives you small pieces on each end. With a square layout, moving the layout over half a tile, so the tile is centered instead of the grout joint, the problem is solved. With running bond, if you move it over half a tile, it puts you right back where you started!! So how do you move the layout over and still keep it centered? Move it over a QUARTER of a tile (1 1/2"). What this does is it'll give you equal, but alternating cuts. Lay it out on paper and try it-- You'll see what I mean. #8) Yes, that's normal. #9) Ya had to give me a hard one!! :-) You're right-- this CAN be tricky. But you're dead on the right track. You need to figure out your coursing (each course is one tile and one grout joint). Lets say yout tile is exactly 3" high, and you're using a 1/4" grout joint. Going by your drawing, I come up with a height of 51 1/2" high. You show a 6x12 piece on the bottomwith the 1/4" joint, that's 6 1/4". Next is 12 courses of subway tile. That's 39 inches (with 12- 1/4" joints). Then the pencil liner, which, if it were me, would get an 1/8" joint (to match the joint in the 3 rows of mosaics), so that's another 1 1/8", and then I'm assuming the chair rail is 2", plus another 1/8" joint, 2 1/8". Just a side note-- this would be another reason for NOT using the chair rail, unless you have the shelf come out over the top of the chair rail. With the other three sides, you can either cap the edges of the niche pieces, or you can have the niche pieces cap the edges of the wall. But the shelf MUST come over the edge of the wall tile. You want any water running down the face of the tile, rather than going into the grout joint. Alot of times, I'll even use a piece of granite tile, and round it out PAST the face of the tile, so that it doesn't even come doen the face of the tile, but actually gives a drip edge. Okay-- back to your niche. Just for the sake of argument, lets say the height is 51 1/2". You want to take into account the thickness of the cement board, as well as the kerdi (figure 5/8"). I would also, as you surmised, give it extra as a "fudge" factor . That way if you need the play, it's there, and if you don't, you can always fill it in with thinset. If it were up to me, and the chair rail was definitely going to stay, I'd set the framing at 50 1/2". The only question is, are you going to set your levels off the finished floor, or off the subfloor? Personally, I'd set it off the subfloor, but when I actually set the tile, set it over the finished floor, cutting it in. That way, if the floor's out of level at all, you'll never see it. Either way, it's up to you. The point is, I'd set the bottom of the niche framing an inch below what you expect the actual coursing to be. #10) That's the way it LOOKS when it's done. :-) You start with a full course above by nailing a piece of wood, and tiling off of that, and then removing it afterward and cutting in the bottom. As for the Kerdi in the shower, you can patch the holes afterward with Kerdi-Fix. You want to wait as long as possible to tile the shower and bathroom floors. You never want to be working over finished work any more than absolutely necessary. #11) I already addressed this above. #12) Install your wood trim first and tile to it. #13) Diamond hole saw. You can check some of the online tile tool supply sites. if you have a hard time locating them, let me know, and I'll see what I can do to find em for you. #14) this is where we get back to the thing about going from center to 1/4 and 3/4 tiles to get back to center. It works with diagonal layout, too. One other thing to think about, and this would work as a nice design feature, too-- from the chair rail up, turn one row of subway tiles on end, running them lengthwise up the sides of your diagonal tiles as a border. WOW!! This reminds me of Rodney Dangerfields's movie Back To School-- to paraphrase right after he finishes the oral exam and says "I feel like I just gave birth!! To an apprentice!!"

Should we frame the niche with the chair rail molding? That IS a possibility: However, so is what your installer wants to do. What he'll do is cut a 45 degree miter on the end of the last piece, and then cut a 45 degree "plug" for the end of it, more or less making his own outcorner. I've done the same thing before, as shown in the following pic, where the chair rail stops at the corner leading into the shower:

Thank you Bill and Lazarus...it sounds like if there are no major disadvantages with it's use, maybe I will just go for it. I imagine the contractor can find it as it was he that suggested using it. I will tell the contractor what you said Lazarus about it being drier than most and being harder to force into the spaces. Do you have any other hints for this first time user? I read it takes longer to dry...do you know anything about that? I really appreciate any help you can give me. Margie

I still have time to change this plan, and order a marble shelf to go in. How would this be done? The bottom tiles would be set, and then the shelf gets set on the top edge of the installed tiles. The top tiles then get cut to take into account the thickness of the stone and still keep alignment with the tiles on either side, and then they get installed. As for objecting to installing on top of the tile, yes and no. ANY kind of intrusion through the tile and waterproofing is cause for concern. But that can also be alleviated if it's "corked" back up with caulking. This one below, I'm showing you the unfinished pictures so you can see how it's done with the stone sitting on the tile's edges: