For all residential buildings other than single- or two-family detached or semi-detached residences, the provisions of Section 23-462 (Side yards for all other residential buildings) shall apply, except that no side yard shall have a width less than 10 feet.

Furthermore, for attached residences that abut an attached building on a separate zoning lot on one side and are bounded by open area on the other side, one side yard with a minimum width of nine feet shall be required for such one or two story residences, and one side yard with a minimum width of 15 feet shall be required for such three or four story residences.