The term "floor area" as employed in Sections 17.54.050 through 17.54.200 shall mean the total interior floor area of a building or structure measured at the inside face of the exterior walls, but excluding stairwells, elevator shafts, lobbies, and in multi-tenant buildings excluding permanent corridors and bathrooms located for common or public usage of the total building rather than for tenant or internal usage, and excluding space occupied by mechanical equipment or space related to the operation and maintenance of the building. (Ord. 1743 § 1 (part), 1999)