Every part of a required yard shall be open to the sky, unobstructed except for accessory buildings in the rear yard, the ordinary projections of skylights, sills, belt courses, cornices, chimneys, flues, and other ornamental features which project into a yard not more than three feet (3'), and open or lattice enclosed fire escapes, fireproof outside stairways, and balconies upon fire towers projecting into a yard not more than five feet (5'). (Ord., 6-8-1989)