The sum of all areas on all floors of a building that cannot be occupied or put to use because of structural building features.
Examples of building features normally classified as structural areas include exterior walls, fire walls, permanent partitions, unusable areas in attics or basements, or comparable portions of a building with ceiling height restrictions, as well as unexcavated basement areas. Source: U.S. Department of Education, National Center for Education Statistics. (2006). Postsecondary Education Facilities