No signs or billboards for the purpose of advertising shall hereafter be constructed or erected in any portion of the city that has heretofore been duly zoned and classified as residential, unless and until such person desiring to erect any sign, signpost or billboard within the area classified and zoned as residential first obtains, in writing, the consent of the owners or duly authorized agent of such owners owning a majority of the frontage of the property on both sides of the street which is adjacent to the block in which such billboard or signboard is to be erected, constructed or located; and such written consent, if obtained, must be filed with the city clerk before any permit shall be issued as hereinafter provided. (Ord. 485, 9-17-1951; amd. Ord. 572, 5-2-1955)