Nonassignable Space

—utility areas of a building required for the function of the building, including stairways; elevators; corridors and interior walkways; public lobbies; restrooms; duct shafts; mechanical rooms; electrical closets; telecommunications closets for voice, data, electrical, security and fire systems; janitor's closets; fireplaces; interior and exterior wall thickness; and exterior amenities that are part of the building but not enclosed, such as loading docks and covered patios, porches and walkways.