Every part of a required yard shall be open and unobstructed from its lowest level to the sky, except for the ordinary projections allowed by the State Uniform Construction Code including, but not limited to, sills, belt courses, chimneys, flues, buttresses, ornamental features, and eaves, provided, however, that none of the aforesaid projections shall project into the minimum required yards more than 24 inches, unless otherwise permitted by this chapter.