Tear out the existing piping (Photos 5 and 6). Then frame the 2×6 walls that will contain the new plumbing and the opposite end of the shower base (Photos 8, 9 and 14). It’s easiest to nail the bottom plate to the floor and the top plate to the ceiling, then fill in the studs one at a time by toenailing them in at the top and bottom. Stack the studs directly in front of the old ones wherever possible. Space the studs in the center of the shower about 12 in. apart to leave room for the shower valve and showerhead. The studs behind the toilet should be spaced exactly 19-3/4 in. apart for securing this toilet chair carrier (Photos 8 and 15).
Turn off the main water supply to the house, and in a convenient location, cut the hot and cold water supply pipes for the bathroom. Also cut out and remove all the existing water lines and fittings in the bathroom. Finally, cut out and remove the vent section leading to the sink and the main stack 5 in. below the vent tee. Stuff rags into open drain lines to keep sewer gas out of the house.