“Main building” means the principal building or other structure on a lot or building site designed or used to accommodate the primary use to which the premises are devoted; where a permissible use involves more than one building or structure designed or used for the primary purpose, as in the case of group houses, each such permissible building or other structure on a lot or building site as defined by this title shall be construed as comprising a main building or structure. (Ord. 2020 § 2, 1994; Ord. 190 Art. IV § 402, 1964)