2016 California Standards for Accessible Design Pocket Guide - Eff. Jan. 1, 2017
11B-903.6 Structural strength.
Benches shall be affixed to the wall or floor. Allowable stresses shall not be exceeded for materials used when a vertical or horizontal force of 250 pounds (1112 N) is applied at any point on the seat, fastener, mounting device, or supporting structure.