The provisions of this chapter shall apply as specifically provided herein to all new buildings and structures and all buildings or structures to which additions, alterations, repairs or change in use or occupancy classification are made as provided in the city’s Building Code. When any such additions, alterations or repairs within any 12 month period exceed 50% of the replacement value of the existing building or structure, the building or structure shall be made to conform to the requirements of this chapter.
(`78 Code, § 15.52.020.)