12-14-5: EXISTING BUILDINGS:
   A.   Continuance Of Use: The lawful use of a building existing at the effective date hereof may be continued, subject to the provisions of this section.
   B.   Change Of Use:
      1.   If no structural alterations are made, a nonconforming use of a building may be changed to another nonconforming use of the same or more restricted classification and shall also apply to nonconforming uses in districts hereafter changed.
      2.   Whenever a nonconforming use of a building has been changed to a more restricted use or to a conforming use, such shall not thereafter be changed to a less restricted use.
   C.   Damaged Buildings: No building which has been damaged by fire, explosion, act of God or the public enemy, to the extent of more than fifty percent (50%) of its value, shall be restored except in conformity with the regulations of this title.
   D.   Discontinuance Of Use: In the event that a nonconforming use of any building or premises is discontinued or its normal operation stopped for a period of two (2) years, the use of the same shall thereafter conform to the regulations of the district in which it is located.
(1980 Code § 36-42)