2019 California Standards for Accessible Design Guide (effective January 1, 2020 with July 1, 2021 amendments)

11B-809.10.6.1 Size.

When one or more shower stalls are provided within the same dwelling unit, as least one shower stall shall comply with one of the following:

1. A transfer type shower compartment 36 inches (914 mm) wide by 36 inches (914 mm) deep with an entrance opening 36 inches (914 mm) complying with Section 11B-608.1 or;

2. A shower stall 30 inches (762 mm) deep minimum by 60 inches (1524 mm) wide minimum with an entrance opening 60 inches (1524 mm) minimum. A water closet shall be permitted to project 12 inches (305 mm) maximum into the opening provided that 36 inches (914 mm) minimum clear space is maintained between the water closet and the shower wall as illustrated in Figure 11B-809.10.6.1 or;

3. A shower stall 36 inches (914 mm) deep by 60 inches (1524 mm) wide minimum with an entrance 36 inches (914 mm) minimum when a wall is installed on the opening side.

FIGURE 11B-809.10.6.1 SHOWERS.