MPAC measures the exterior of a building to determine the total area or square footage of the building. The building area does not include the basement area, decks, porches or garages. In circumstances where a room or rooms are open to the second floor, such as in the case of a cathedral or vaulted ceiling, the area of the open space is included with the second floor area.
The building size is divided into separate floor areas (i.e., first, second or upper floor). The upper floor area is the total of the third floor area and upward and uses exterior measurements.