Gross Floor Area (GFA)
The sum of the floor areas of the spaces within the building, including basements and mezzanine and intermediate-floored tiers; excludes non-enclosed (or non-enclosable) roofed-over areas, such as exterior covered walkways, porches, terraces or steps, roof overhangs, and similar features; measured from the exterior faces of exterior walls or from the centerline of walls separating buildings.