"Nonconforming structure" means a structure which was lawful when established which does not now conform to the setback, height, or lot coverage requirements of the zone in which it is located. (Added by Amended Ord. 02-064, Dec. 9, 2002, Eff date Feb. 1, 2003; Amended by Amended Ord. 13-007, Sept. 11, 2013, Eff date Oct. 3, 2013).