No person shall alter or repair any wood, frame, brick cased or brick veneered building within the fire district of the City which is not in accordance with Sections 1313.01 to 1313.06 inclusive, except those buildings heretofore mentioned in Section 1313.01, when such building has been damaged by fire, decay or action of the elements to the extent of fifty percent of the original value of such building, exclusive of the value of the foundation thereof. The roof of any building which has been damaged from any cause whatever, more than fifty percent of its original value, shall be replaced by a roof covered with incombustible material.
(1964 Code §51.24)