Is that going floor to ceiling when it is going vertical? There shouldn't be an issue then. If you do a miter corner, I am thinking a color matched caulk would go there as opposed to grout. Hopefully the wonderful tile pros will stop by and give more advice...

Great! Question!!

Trying to understand your issue. Those tiles should be backfilled with thinset mortar prior to or upon installation for stability. It has nothing to do with grout.

Most tile like that is made with a bevel not a flat edge. You are filling the bevel with grout. Grout has a fairy thick consistency and it will cling to the tile. Im understanding your question to be that do to the profile of the tile there is a gap between the tile and the wall and you think the grout will push through?

Are you butting them or using spacers? In either situation it will be fine just be careful while packing it in.

Thinset should fill the void, also your grout will not "flow". Push it after setting the tile and do it again if there are gaps.

The shelf shelf rail tile is going to run from the left just under the cabinet (in yellow insulation) to the showers opening - then up and over, down again to another shelf rail height. We plan to use it as well for the shower's niche. We will have a 1/16" gout spacing. Thanks!

Typically what the other kids wrote; you'd back-butter the trim piece to fill that void with thinset, then set it on the wall. When grouting, when the grout is packed in the joints, the cured thinset will backstop the grout.

Looks like the doorway is lined with a wood door jamb, maybe plywood? Will you be tiling directly upon that?

Dear MongoCT - You have a keen eye! I am not sure actually. My wonderful team are making all nice and square. They have carefully coursed out the tiles to minimize any cut tiles. I like the term back-butter - quite a nice visual for me. It seems that you are all saying to use thin set and allow to dry the trim pieces to dry then use for the project. This concept of a wet-room is gaining popularity. My mother uses a walker and I was very keen to have it with no curb. The shower pan is from a UK company and is very study - better than the Schluter one we considered. The membrane and waterproofing is from Ardex. The local rep was very informative and guided us to the use of his materials. The floor has been properly pitched and even tested with a generous bucket to assure the water travels just right to the drain. I am very excited to see the end of this project and actually see it in operation.

All helping - Thanks ever so much!

I believe that the thinset is to set the trim tile in place and fill it all at the same time, not fill that curved space, let it dry, then install.

AT least that is how I understand it. If your tilers are already figuring out exactly how to lay out the tiles for minimal cuts, that's a good sign.. I would ask them what their process is for a tile like that and then you can post their response here and see what the tile pros say...

MongoCT is asking this for a specific reason.

"Looks like the doorway is lined with a wood door jamb, maybe plywood? Will you be tiling directly upon that?"

I will ask them tomorrow. We did get the crown molding done today.