GROSS FLOOR AREA

means the sum of the total area of all floors of a building or buildings (including any void area in each of those floors, such as service shafts, liftwells or stairwells), measured: where there are exterior walls, from the exterior faces of those exterior walls where there are walls separating two buildings, from the centre lines of the walls separating the two buildings where a wall or walls are lacking (for example, a mezzanine floor) and the edge of the floor is discernible, from the edge of the floor.