"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 usable or unused under-floor space is more than six feet above grade for more than fifty percent of the total perimeter or is more than twelve feet above grade at any point, such usable or unused under floor space shall be considered as a story.

(Ord. 650 §4, 1985).