Your shower tile is surface mount so you can simply remove the trim piece at the point you want to start the subway tile and butt it into the existing square tiles.
Adding tile to existing tile.
If so check out the classes at home depot lowes might also have them for tile installation.
It was relatively solid looking.
It had the same rustic feel.
Tap the on the top left corner of your screen.
On the add a device page choose tile for tile partner products follow the prompts on your device press the button on your tile device and listen for the tune.
Tile loads are usually higher than 10 psf so chances are your trusses were not designed to account for this.
Lay a level on the old tile and mark any high spots.
Scrub the wall tiles with diluted degreasing cleaner and a nylon scrub brush.
Out of all the tiles my client had collected this one was the clear winner for these reasons.
Layer newspaper on the floor across the bottom of the tiled wall.
Sounds like this is a new adventure for you.
A couple other considerations are the on center o c spacing of the trusses.
Mix degreasing cleaner with water in a bucket using a dilution recommended by the cleaner manufacturer.
Hold the tile close to your device until they connect it should take about ten seconds.
Grind them down with a grinder.
Roughen the tile with 80 grit sandpaper.
Open the tile app on your smartphone or tablet.
By adding cement board and tile to the floor you will be increasing the top chord dead load.
If your old ceramic tile is worn or dated you can lay new tile right over the old and avoid the huge job of tearing out the old tile.