Residential structure designed to house more than one family. Smaller multifamily housing units include duplexes, triplexes, and quadriplexes. Larger multifamily housing is normally termed an apartment house. Multifamily housing can be tenant owned individually or as a condominium or cooperative or it can be rented. Multifamily housing structures of 2 to 4 units grew the most slowly during the 1980"s, increasing only 1%. Units in larger buildings of 5 or more units, increased 16%.