2010 ADAS 303.2 – Changes in Ground Surface Level – Vertical
Where changes in level are permitted in floor or ground surfaces, changes in level of 1/4 inch high maximum shall be permitted to be vertical.
2010 ADAS 303.3 – Changes in Ground Surface Level – Beveled
Where changes in level are permitted in floor or ground surfaces, changes in level between 1/4 inch high minimum and 1/2 inch high maximum shall be beveled with a slope not steeper than 1:2.
Code according to 2010 ADAS. Check your state’s accessibility laws. Some states such as California, Georgia and Florida have additional requirements and standards.