Patio fences may be erected in rear yards only, to a height of six
feet (or average of six feet for stepped fencing) extending a maximum
of 10 feet from the rear wall of the original building parallel to
and along the party lot line of duplex houses. Such fence may be of
wood materials, pierced masonry or ornamental iron providing not less
than 10% daylight openings. In the case of a stepped fence, no portion
shall be higher than the bottom of the facia board of original construction
and the highest point will be adjacent to the building.