“Story” is that portion of a building included between the upper surface of any floor and the upper surface of the floor next above, except that the topmost story shall be that portion of a building included between the upper surface of the topmost floor and the ceiling or roof above. If the finished floor level directly above a basement, cellar or underfloor space is more than six feet above grade as defined in Section 17.04.310 of this title, for more than fifty percent of the perimeter, or is more than twelve feet above grade as defined herein at any point, such basement, cellar or underfloor space should be considered as a story. (Ord. 2694 § 1, 1982; prior code § 17.08.530)