California Code, Financial Code - FIN § 5114

(a) A structure or structures designed or used primarily for residential rather than nonresidential purposes and consisting of more than one dwelling unit.

(b) A structure or structures designed or used primarily for residential rather than nonresidential purposes for students, residents, and persons under the care of, or the employees or members of the staff of, an educational, health, or welfare institution or facility.

(c) A structure or structures that are used in part for residential purposes for not more than one family and in part for business purposes if the residential use of the structure or structures is substantial and permanent and not merely transitory.