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

11B-405.7.5 Doorways.

Where doorways are located adjacent to a ramp landing, maneuvering clearances required by Sections 11B-404.2.4 and 11B-404.3.2 shall be permitted to overlap the required landing area. Doors, when fully open, shall not reduce the required ramp landing width by more than 3 inches (76 mm). Doors, in any position, shall not reduce the minimum dimension of the ramp landing to less than 42 inches (1067 mm).

[2010 ADA Standards] 405.7.5 Doorways. Where doorways are located adjacent to a ramp landing, maneuvering clearances required by 404.2.4 and 404.3.2 shall be permitted to overlap the required landing area.

Advisory 11B-405.7.5 Doors at ramp landings. Where a door swings onto a ramp landing width, additional ramp landing length as specified may be necessary to accommodate a clear level area for the wheelchair user to clear the door swing and not risk rolling backward down the ramp run. Where the ramp width is less than the landing width, additional ramp landing length may be provided as a level extension at the top of the ramp run, or the entire width of the landing. ◼