The only area a topical waterproof membrane makes any sense is installed over a sloped mud pan run up the wall a few inches and wrapped over the shower damn step.
Shower wall put thinset on tile or backerboard.
Repeat for the rest of the tiles.
Thin set dries slowly allowing you to fix and readjust backerboard sheets as needed.
It must be easy to work with and it must adequately fill in gaps between the tile and the substrate.
With the smooth side of a 1 4 inch notched trowel spread enough mortar for one sheet.
I never recommended using drywall as a base for the installation only a rated tile backerboard as well as the option you suggested.
Kerdi can also be installed directly over standard drywall in a shower because when installed correctly it creates a continuous waterproof barrier.
Sitting standing water is where the problem is.
It cannot cure too fast.
Step 5 cut and lay the remaining tiles.
The first row tiles must be sitting on the spacers you put down.
Most tile have a recommended grout that works well with them so check your manufacturer s instructions.
Whether wall or floor tile that tile needs to thoroughly stick to its base surface demands placed on tile adhesive are both extensive and steep.
The thin set in a bag would be as much weight once installed as the tile it is adhering even if it was rated to hold.
I plan on thinsetting and screwing cement board to the subfloor then redgard then thin set and tile.
Once the thinset has dried for 24 hours remove the spacers and prepare the wall for grout.
Work it into the spaces using a diagonal motion.
Use thin set mortar when installing cement backerboard.
Waterproof sheet membrane such as schluter kerdi is applied to the cement board with thinset adhesive.
After the thinset has dried tile is applied to the sheet membrane with thinset.
The amount of water that seeps through the tile and grout and backer board of a shower wall is minuscule.
Starting from the bottom of the main design lay the cut tiles in the same ways as the full tiles.
Mix a small amount of grout at a time and apply it with a rubber float.
I need to match the height of the existing tile in the bathroom.
Ridge the mortar with the notched side of the trowel.
Tile adhesive is expected to hold the tile in place not just for years but for decades without fail.
Otherwise you do.
Apply thinset mortar with a u notch trowel to the back of each tile and place the tile against the wall then give it a firm push.
By using the proper techniques you can apply the thinset mortar to your shower wall and be confident that the tiles you install will remain in place as the mortar sets and hardens.