No existing structure devoted to a use not permitted by this chapter in the zone in which it is located shall be enlarged, extended, constructed, reconstructed, moved or structurally altered in any manner which would increase or intensify the density or actual living quarters for such structure except in changing the use of the structure to a use permitted in the zone in which it is located, provided, however, this section shall not preclude a zoning certificate and building permit from being issued if the proposed enlargement, extension, construction or reconstruction is for a garage, staircase, deck, fence, shed or any other addition which does not increase the actual living quarters of the existing structure, and the enlargement, extension, construction, reconstruction or alteration is conforming in all other respects to this chapter.

Any nonconforming use may be extended throughout any parts of a building which were manifestly arranged or designed for such use as of August 11, 1972, but no such use shall be extended to occupy any land outside such building.

If no structural alterations are made, any nonconforming use of a structure, or structure and premises, may 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.

Any structure, or structure and land in combination, in or on which a nonconforming use is superseded by a permitted use shall thereafter conform to the regulations for the zone in which such structure is located, and the nonconforming use may not thereafter be resumed.

When a nonconforming use of a structure, or structure and premises in combination, is discontinued or abandoned for nine consecutive months or for 18 months during any three-year period, the structure, or structure and premises in combination, shall not thereafter be used except in conformance with the regulations of the zone in which it is located.

Where 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.

A nonconforming structure may be elevated so as to allow for parking and/or storage underneath the structure provided there are no changes to the existing footprint, there are no substantial alterations that would otherwise require appearance before the Land Use Board and the height of the structure is within the limitations allowed by current ordinances.