A.    No accessory building shall be constructed upon a lot until the construction of the main building has been actually commenced, and no accessory building shall be used for dwelling purposes unless the main building on the lot is also being used for dwelling purposes.

    B.    More than one industrial, commercial, multiple dwelling or institutional building may be erected upon a single lot or tract, but the yards and open spaces required around the boundaries of the lot or tract shall not be encroached upon by any such buildings, nor shall there be any change in the intensity of use requirements.

    When more than one multiple dwelling building is erected upon a single lot or tract, the minimum distances between main buildings shall be the following:

    1.    Front to front, seventy (70) feet; front to rear, sixty (60) feet;

    2.    Side to side, one-half the height of the taller building, but not less than twenty (20) feet;

    3.    Front to side or rear to side, the height of the taller building, but not less than thirty (30) feet;

    4.    Rear to rear, fifty (50) feet;

    C.    Where an open space is more than fifty (50) percent surrounded by buildings, the minimum width of the open space shall be thirty (30) feet for one-story buildings, forty (40) feet for two-story buildings, and fifty (50) feet for three-story buildings. (Prior code § 40-10-2(B))