NYC Building Code 2008: Area Definitions

FLOOR AREA, GROSS. The floor area within the inside perimeter of the exterior walls of the building under consideration, exclusive of courts, without deduction for corridors, stairways, closets, the thickness of interior walls, columns or other features. The floor area of a building, or portion thereof, not provided with surrounding exterior walls shall be the usable area under the horizontal projection of the roof or floor above. The gross floor area shall not include interior courts.

FLOOR AREA, NET. The actual occupied area not including the thickness of walls, partitions, columns, furred-in spaces, fixed cabinets, equipment, and unoccupied accessory areas such as corridors, stairways, toilet rooms, mechanical rooms and closets.