If lawful use involving individual structures with a replacement cost of $1,000.00 or more, or of structure and premises in combination, exists at the effective date of adoption or amendment of this chapter that would not be allowed in the district under the terms of this chapter, the lawful use may be continued so long as it remains otherwise lawful, subject to the following provisions:
1. No existing structure devoted to a use not permitted by the zoning ordinance in the district in which it is located shall be enlarged, extended, or structurally altered except in changing the use of the structure to a use permitted in the district in which it is located.
2. Any nonconforming use may be extended throughout any parts of a building which were manifestly arranged or designed for such use at the time of adoption or amendment of the zoning ordinance, but no such use shall be extended to occupy any land outside such building.
3. If no structural alterations are made, any nonconforming use of a structure, or structure and premises, may as a special exception be changed to another nonconforming use provided that the Board of Adjustment, either by general rule or by making findings in the specific case, shall find that the proposed use is equally appropriate or more appropriate to the district than the existing nonconforming use. In permitting such change, the Board of Adjustment may require appropriate conditions and safeguards in accordance with the provisions of this chapter.
4. Any structure, or structure and land in combination, in or on which a nonconforming use is superseded by a permitted use, shall thereafter conform to the regulations for the district, and the nonconforming use may not thereafter be resumed.
5. When a nonconforming use of a structure, or structure and premises in combination, is discontinued or abandoned for 12 consecutive months or for 18 months during any three-year period (except when government action impedes access to the premises) the structure, or structure and premises in combination, shall not thereafter be used except in conformity with the regulations of the district in which it is located.
6. When nonconforming use status applies to a structure and premises in combination, removal or destruction of the structure shall eliminate the nonconforming status of the land. Destruction, for the purpose of the subsection, is defined as damage to an extent of more than 75 percent of the replacement cost at time of destruction. Replacement shall begin within six months of the time of destruction or the nonconforming status shall expire. Said construction shall also be completed within 18 months of the time of destruction or the nonconforming status shall expire.