small bath heated tile floor and tile walls

[rangert]

A picture would make this easier, but that is all in my head at this point. The BR is about 10' X 8' and the floor is plywood over floor rafters built in 1973. I want to put down a heated ceramic tile floor to replace a 16X16 tile floor I put down several years ago and to replace existing 4X4 wall tiles in bath and dry area of the room with 3X6 white tiles over new hardibacker. I also want to use what I am going to call 'cove base' tiles that match the white wall tiles and have a cove shaped transition to the floor tile. I have seen this at a new Books-a-Million bathroom and it looks so clean.

Several questions:
1) How do I do inside and outside corners with the cove base tiles? Do I cut matching edges at 45 degrees like I would do for wood? Or cope one tile? Or just butt them and get creative with grout? Are there special inside/outside corner tiles available?

2) What about expansion with the tile-to-tile wall and floor? With both wall and floor tiles and the cove base there seems no space for expansion. Maybe use some kind of silicone caulk at the floor to cove base joint?

3) Is the heated tile going to make this expansion a bigger problem?

Thanks in advance for the help. I spend a few hours reading other posts, but no-one really spoke to the cove base tile issues.

[Tilebri]

Here's how I would do it in your case. Install cbu of your choice over the subfloor, then install your mats and then embed them in SLC. You need to maintain a perimeter gap around the room and foam weather seal works great for that. Then I'd cover the floor with an antifracture membrane of your choice to help isolate the tile from the shear stresses of the floor's heating and cooling cycles. The slc is a very important step as your wall installation with cove will go much easier with a completely level perimeter base. Dry lay a cove tile along the wall and with a fine tip sharpie marker, slide the tile along the wall (do each wall) marking where the cove will extend past the wall. Measure in from the cove marking 1 grout joint width. That's where your floor tile ends and when you set the cove tile, that joint will be filled with a color matching caulk.

I wouldn't go less than 1/8" for the joint though.

There's no need to use hardi on any of the dry area walls receiving tile, unless you like dealing with the added cumbersomeness of the hardi and the waste generated since it doesn't sync up to 16" oc wall framing.

Inside corners of cove can me mitered and outside corner pieces are available. There might be just one outside corner avail. or there might be both left and right pieces available.

You don't say if there are any existing issues with your current tile that inspired your decision to change out the floor. Just to make us all a bit more comfortable, what's there for your subfloor, and what's the size, spacing and unsupported span of your joists?