2022 California Standards for Accessible Design Guide (effective January 1, 2023)

1009.7.4 Stairways.

Stairways that are part of the means of egress for the exterior area for assisted rescue shall provide a minimum clear width of 48 inches (1220 mm) between handrails.

Exception: The minimum clear width of 48 inches (1220 mm) between handrails is not required at stairways serving buildings equipped throughout with an automatic sprinkler system installed in accordance with Section 903.3.1.1 or 903.3.1.2.