As set forth in Subtitle B §§ 100.2 and 304.7 of the Zoning Regulations, an interior space of a building is considered to contain gross floor area [GFA] when it has structural headroom of 6 feet 6 inches or greater. The relevant Sections of the Zoning Regulations are: 

B-100.2 Definitions:  
Story: The space between the surface of two (2) successive floors in a building or between the top floor and the ceiling or underside of the roof framing as measured in accordance with §310 of this subtitle. For the purpose of determining the maximum number of permitted stories, the term “story” shall not include cellars, penthouses, or rooftop structures. 

Gross Floor Area (GFA): Unless otherwise specified, the sum of the gross horizontal areas of all floors of all buildings on a lot, measured from the exterior faces of exterior walls and from the center line of walls separating two (2) buildings as measured in accordance with § 304 of this subtitle, except as may be stated elsewhere in this title 

B-304. Rules of Measurement for Gross Floor Area (GFA) 
B-304.7: GFA shall include. . .attic space (whether or not a floor has actually been laid, providing structural headroom of six feet, six inches (6 ft., 6 in.) or more). . . 

When applying these provisions to an attic space, a determination must first be made as to whether the horizontal area within the attic counts toward the building’s GFA. Under the rule of measurement of GFA, an attic space that provides structural headroom that is less than 6 feet 6 inches is not counted as building GFA. Structural headroom is measured from the top of the horizontal roof beam if no floor has been laid and may be measured from the top of a finished floor if one has been provided. 

The definition of story under B-100.2 establishes that a story may be located between the top floor and the ceiling or underside of the roof framing. The top of the horizontal structural beam at the ceiling of the top floor defines the floor of the attic whether a floor has been laid or not. The clear distance from the top of the structural ceiling of the top floor to the underside of the roof framing is the critical dimension needed to establish whether that space between the top floor and the roof will count as a story. 

Section B-304.7 limits the ability for that attic space to be counted as GFA by requiring a minimum of 6 feet 6 inches of structural headroom or clear floor to ceiling height. The Zoning Administrator has determined that an attic area with less than 6 feet 6 inches is not considered to be a story because it does not count toward building GFA.