Service of any order made pursuant to Section 1503.04 by the Fire Marshal may be made upon the owner of the building, structure or premises involved:
(a) By delivering a copy of the order to the owner personally;
(b) By delivering a copy of the order to any adult occupant or person in charge thereof; or
(c) In the event that the owner, occupant or person in charge cannot with reasonable diligence be found, by affixing a copy of the order in a conspicuous place upon the door or entrance to the building, or upon a conspicuous place on the structure or premises, and in addition thereto, by mailing a copy thereof by certified mail to the last known post office address of the owner or to his address as it appears upon the tax records of the County.
(1979 Code 94.05)