2013 California Standards for Accessible Design Pocket Guide

1017.3 Aisles in Groups B and M.  In Group B and M occupancies, the minimum clear aisle width shall be determined by Section 1005.1 for the occupant load served, but shall not be less than 36 inches (914 mm).

Exception:  Nonpublic aisles serving less than 50 people and not required to be accessible by Chapter 11B (see Section 11B-403) need not exceed 28 inches (711 mm) in width.