The chief of the bureau of fire prevention shall have power to modify any of the provisions of the fire prevention code upon application in writing by the owner or lessee, or his duly authorized agent, when there are practical difficulties in the way of carrying out the strict letter of the code; provided, that the spirit of the code shall be observed, public safety secured and substantial justice done. All modifications shall first be approved by the governing body. (Prior code § 4-2-24)