California Code, Health and Safety Code - HSC § 19100

(a) Any building not intended primarily for occupancy by human beings and located entirely outside the limits of a city or city and county.

(b) Any building designed and constructed for use exclusively as a dwelling by not more than two families and located entirely outside the limits of a city or city and county.

(c) Any building designed and constructed primarily for use in housing poultry, livestock, hay, grain, or farm machinery and supplies, even though persons may work in, or may otherwise be present in, such building from time to time.

(d) Any building under construction on and prior to May 26, 1933.

(e) Any building in an unincorporated area and used for human habitation and of wood frame construction and not more than two stories in height, in which the span between bearing walls does not exceed twenty-four feet (24′), no room in which contains an area of more than one thousand square feet (1,000 sq. ft.), and which is located in a labor camp as defined in Section 2410 of the Labor Code.  1