All houses or buildings erected within the city and required to be numbered under the provisions of this title shall be numbered as provided in this chapter on or before the first day of July, 1928. All numbers previously placed upon such buildings which do not conform to the numbers provided in this chapter shall be changed within said period of time so as to conform to the numbers fixed and established by this chapter. All houses or buildings required to be numbered under provisions of this chapter which shall hereafter be erected shall be numbered in accordance with the provisions of this chapter before the same are occupied. (Ord. 1770 §5, 1928).