If a building or other structure containing a nonconforming use is damaged or destroyed by any means to the extent of fifty percent (50%) or more of its replacement value at that time, the building or other structure may be rebuilt or used thereafter only for a conforming use and in compliance with the provisions of this title. In the event the damage or destruction is less than fifty percent (50%) of its replacement value, based upon prevailing costs, the building may then be restored to its original condition and the occupancy or use of such building may be continued which existed at the time of such partial destruction. In either event, restoration or repair of the building or other structure must be started within a period of one year and diligently prosecuted to completion. (1983 Code)