(a) The office of the principal place of business and each branch location of the firm must be established to the extent that its construction is not temporary, transitory or mobile in nature, except that a trailer coach office is acceptable providing it is not a part of the dismantling inventory, and otherwise meets the requirements of Vehicle Code Section 320.

(b) Office in Private Residence. In considering any application for a vehicle dismantler's license wherein the established place of business is a part of any single or multiple-unit dwelling house, the department may require additional proof of the applicant's status as an actual dismantler pursuant to Vehicle Code Section 11514 in the form of confirmation from the local zoning authority in the city, county, or city and county, that the property is properly zoned for the conduct of such business.