If
any non-conforming use or structure is destroyed by any means, including
flood, it shall not be reconstructed if the cost is more than fifty
percent (50%) of the market value of the structure before the damage
occurred except that if it is reconstructed in conformity with the
provisions of this Chapter. This limitation does not include the cost
of any alteration to comply with existing State or local health, sanitary,
building or safety codes or regulations or the cost of any alteration
of a structure listed on the National Register of Historic Places
or a State Inventory of Historic Places.