A mezzanine is an intermediate floor between the main levels of a building. It often overlooks the floor below and is partially open to it. The word comes from the Italian mezzano, meaning middle. In a theater, the mezzanine is the first balcony above the orchestra. In a warehouse, it might be a small office platform above the shop floor.

Mezzanines add usable space without adding a full story. They are common in industrial buildings, retail stores, and restaurants where the ceiling is high enough to accommodate an extra level. They can be temporary or permanent, open or enclosed.

Building codes treat mezzanines carefully. A mezzanine may be counted as part of the floor below or as a separate story, depending on its size and how it is enclosed. Egress, fire separation, and accessibility requirements all apply. The definition matters because it affects how the building is classified.

Structurally, a mezzanine can be supported by columns, hung from the roof structure, or cantilevered from a wall. The choice depends on the building and the loads it must carry.