The State Historic Building Code, Title 24, of the California Administrative Code, shall be applicable to the issuance of Building Permits for changes to the interior and/or exterior of structures designated as historic resources. If proposed improvements to a structure not previously designated as an historical resource would make the structure eligible to be designated as an historical resource, and if the owner submits an application for such designation by the County, then the Historic Resources Commission may authorize the application of the Historic Building Code to the issuance of Building Permits for the proposed improvements.