Whenever the use of a building shall become nonconforming through an amendment to this title or the district boundaries, such use may be continued and, if no structural alterations are made, may be changed to another nonconforming use of the same or of a more restricted classification. No accessory use or building shall be added to a nonconforming lot or lot containing a nonconforming building or structure. (Ord. 03-O-9, 3-18-2003)