A.    Schools, churches, hospitals, and other buildings of an institutional character permitted in a district may have a building height in excess of the district limitations but not in excess of seventy-five (75) feet; provided that the requirements in the district for front, rear and side yards shall be increased by one foot for each foot of the building height in excess of forty (40) feet. A television or radio antenna may be of a height not exceeding ninety (90) feet.

    B.    The building height limitations set forth in this title apply generally to structures, also, but shall not apply to chimneys, church spires, flag poles, or to mechanical appurtenances necessary and incidental to the permitted use of a building.

    C.    Where the natural ground slope of a lot on the downhill side of the street is greater than one foot in seven feet as measured from the front lot line to the grade at the rear wall of the proposed building, one story in addition to the number permitted in the district in which the lot is situated is permitted on the downhill side of any building. The building height shall not otherwise exceed the limit specified for said district. (Prior gen. code §§ 8-60.9--8-60.11)