A.   Except when authorized by the board of adjustment and appeals, as provided in title 2, chapter 4 of this code, no building or premises containing a nonconforming use shall hereafter be extended unless such extension shall conform with the provisions of this ordinance for the zone in which it is located; provided, however, that a nonconforming use may be extended throughout those parts of a building which were manifestly arranged or designed for such use prior to the time of enactment of this ordinance, if no structural alterations, except those required by law or ordinance, are made therein.
   B.   Any nonconforming building or structure which has been or may be damaged by fire, flood, explosion, earthquake, war, riot or act of God, may be reconstructed and used as before, if it be done within twelve (12) months of such calamity and if the area restored does not exceed the square foot area as it existed at the time of such calamity.
   C.   No building, structure or premises where a nonconforming use has been or may be discontinued for more than six (6) months or has been or may be changed to a use permitted in the zone in which it is located, shall again be devoted to a nonconforming use. (Ord. 168)