It is the area in terms of square m/ft/inch of the floor.

The square footage of a building or space.

The total space covered by all floors in a building.

is the space on any storey of a building between exterior walls and required firewalls including the space occupied by interior walls and partitions, but not including exits, vertical service spaces, and their enclosing assemblies.

The total of all the horizontal areas of all the floors in a building.

The sum of the gross horizontal areas of the several floors of a building, measured from the exterior faces of exterior walls or from the center line of common walls separating two (2) buildings. Floor area, for the purposes of these regulations, shall not include basement, garage, elevator, and stair bulkheads, attic space, terraces, breezeways, open porches, and uncovered steps.