( Condominium, public housing, owner-occupancy, etc.) Housing Development Board flats in Punggol, Singapore Typically, mixed-use buildings consist of businesses on the lower floors (often retail in street-facing ground floor and supporting subterranean levels) and residential apartments on the upper floors. 'Mixed-use buildings' combine commercial and residential uses within the same structure. The word 'unit' is generally used only in the context of a specific building. In some countries, the word ' unit' is a more general term referring to both apartments and rental business suites. In the UK, the term apartment is more usual in professional real estate and architectural circles where otherwise the term flat is used commonly, but not exclusively, for an apartment on a single level (hence a 'flat' apartment). The term apartment is favored in North America (although in some cities flat is used for a unit which is part of a house containing two or three units, typically one to a floor ).
