A structure or the use of a structure or premises which was lawful before the passage or amendment to this chapter, but which is not in conformity with the provisions of this chapter, may be continued subject to the following conditions:
1. If such use is discontinued for six consecutive months, and future use of the building premises shall conform to this chapter.
2. Uses or adjuncts thereof that are or become nuisances shall not be entitled to continue as nonconforming uses.
If any nonconforming 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 unless 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, provided that the alteration shall not preclude its continued designation.