No permit issued by the division for a relocatable office building for use or occupancy for any commercial or industrial purpose shall be valid for a period of time exceeding three hundred sixty five (365) days, provided that upon a showing in writing of extreme hardship by the applicant, the division of building and housing services may, at its option, grant the applicant an extension not to exceed sixty (60) days. No more than one such permit extension may be granted for such use or occupancy of any temporary relocatable office buildings. (Prior code § 5-16-3)