Within the city, or within the contiguous unincorporated territory two miles in all directions from the corporate limits of the city, it is unlawful for any person to erect, construct, enlarge, alter, repair, move, improve, remove, convert or demolish any building or structure, or any part or portion thereof, including, but not limited to, the plumbing, electrical, ventilating, heating or air conditioning systems therein, or cause the same to be done, without first obtaining a separate building permit for each such building, structure or mechanical components from the city.