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

11B-303 Changes in level

11B-303.1 General.

Where changes in level are permitted in floor or ground surfaces, they shall comply with Section 11B-303.

Exceptions:

1. Animal containment areas shall not be required to comply with Section 11B-303.
2. Areas of sport activity shall not be required to comply with Section 11B-303.

11B-303.2 Vertical.

Changes in level of ¼ inch (6.4 mm) high maximum shall be permitted to be vertical and without edge treatment.

[2010 ADA Standards] 303.2 Vertical. Changes in level of ¼ inch high maximum shall be permitted to be vertical.

FIGURE 11B-303.2 VERTICAL CHANGE IN LEVEL

11B-303.3 Beveled.

Changes in level between ¼ inch (6.4 mm) high minimum and ½ inch (12.7 mm) high maximum shall be beveled with a slope not steeper than 1:2.

Advisory 11B-303.3 Beveled. A change in level of 1/2 inch (13 mm) is permitted to be 1/4 inch (6.4 mm) vertical plus 1/4 inch (6.4 mm) beveled. However, in no case may the combined change in level exceed 1/2 inch (13 mm). Changes in level exceeding 1/2 inch (13 mm) must comply with Sections 11B-405 (Ramps) or 11B-406 (Curb Ramps). ◼

FIGURE 11B-303.3 BEVELED CHANGE IN LEVEL

11B-303.4 Ramps.

Changes in level greater than ½ inch (12.7 mm) high shall be ramped, and shall comply with Section 11B-405 or 11B-406.

11B-303.5 Warning curbs.

Abrupt changes in level exceeding 4 inches (102 mm) in a vertical dimension between walks, sidewalks or other pedestrian ways and adjacent surfaces or features shall be identified by warning curbs at least 6 inches (152 mm) in height above the walk or sidewalk surface.

Exceptions:

1. A warning curb is not required between a walk or sidewalk and an adjacent street or driveway. 
2. A warning curb is not required when a guard or handrail is provided with a guide rail centered 2 inches (51 mm) minimum and 4 inches (102 mm) maximum above the surface of the walk or sidewalk.