Adjacent Wall Seams Come Next
I spread thinset on the shower floor and up the first adjacent shower wall about 6 inches. Because there was no shower threshold, I extended the membrane well into the main bathroom area.
Again I applied a strip that bridged the seam between the wall and floor, and I went over the membrane with a taping knife to fully press the membrane into the thinset.
At the shower corners, I spread thinset and installed prefabricated 3 dimensional inside corners made out of the membrane.
The adjacent wall on the other side of the shower got similar treatment with the strip across the floor/wall seam along with a 3-D inside corner.
Piecing In
Onto the Main Floor