Lawful nonconforming buildings and structures existing at the time of the passage of this chapter or any amendment thereto shall be allowed to remain subject to the following provisions:
   (A)   A nonconforming building or structure shall not be extended or enlarged unless the extension or enlargement complies with all of the requirements of this chapter for the district in which it is located; and
   (B)   Any nonconforming building or structure which is damaged by fire, flood, wind or other act of God or humans to the extent of 50% or more of its fair sales value immediately prior to damage shall not be repaired or reconstructed except in conformity with the provisions of this chapter.
(2000 Code, App. B, § 34)