It shall not be lawful to occupy with building materials any street, parkway, sidewalk or alley or any part thereof other than that immediately in front of or adjoining the lot or land upon which the building is being erected; provided, that if the written consent of the owners, tenants or occupants of properties adjoining the site of any proposed building is first obtained and filed with the Building Commissioner, the occupation of the street, parkway, sidewalk or alley may be extended in front of the property so consenting, upon the same terms and conditions as those fixed for the occupation of the street in front of the building site. (1965 Code)