A mezzanine floor is a level in a room with a double-height or larger ceiling that splits it into two floors but does not extend to the entire area of the room in which it is located and is accessible from it. The terms come from the Italian word ‘mezzanino’ which roughly means ‘middle’ and refers to the way in which a mezzanine floor splits the height of a room.
A mezzanine is not counted as a floor in the building and usually is not included when calculating a building’s floor area. According to the International Building Code, a mezzanine can be no larger than one-third of the overall area of the floor in which it is located. More than one mezzanine is permitted but once again the sum total of the area of all mezzanines in a room must be no greater than a third of the room’s floor area.