“Main building” means a building in which is conducted the principal use of the building site on which it is situated. In any residential district, any dwelling, except for a detached secondary dwelling unit, shall be deemed to be a main building, or part of a main building, on the building site on which the same is situated. (Ord. 2020-07 § 2, 2020; Ord. 2003-09 § 1, 2003; Zoning Ordinance dated 7/94, 1994)