Cal. Health & Safety Code § 17922.15

(a) At the next triennial building standards rulemaking cycle that commences on or after January 1, 2020, the Department of Housing and Community Development shall investigate possible changes to the building standards in the California Residential Code (Part 2.5 of Title 24 of the California Code of Regulations) that promote aging-in-place design and are limited to all of the following:
1. (1) The location of doorbells, light switches, and heating, ventilation, and air-conditioning (HVAC) controls that are reachable by those with mobility impairments.
2. (2) The installation of support backing for the later installation of grab bars in one or more bathrooms.
3. (3) The provision of a 32-inch clearance in the width opening for one bathroom door and one bedroom door on the ground floor, or, in the case of a two- or three-story single-family dwelling, on the second or third floor of the dwelling if a bathroom or bedroom is not located on the ground floor.
(b) If the department determines that one or more of the changes described in subdivision (a) can be incorporated into the California Residential Code without significantly increasing the cost of construction, the department may propose building standards to that effect for consideration by the California Building Standards Commission. The department shall include in any proposed building standard, regarding the 32-inch clearance width for a bathroom and bedroom door described in paragraph (3) of subdivision (a), a finding whether a delay of 18 months in the effective date of that proposed building standard is warranted to provide adequate time for industry to incorporate this change into standard designs.