The lawful use of a building existing at the time of adoption of this Chapter (September 5, 1989) may be continued, although such use does not conform with the provisions of this Chapter or any amendment thereto, and such use may be extended throughout the building; providing that no structural alterations except those required by law or ordinance are made therein.

No building which has been damaged by fire, explosion or act of God to the extent of more than fifty percent (50%) of its market value shall be restored except in conformity with the regulations of this Chapter, provided that, in any multiple-family dwelling unit located in an "R-3" Multiple-Family Residential District which has been rehabilitated under the Internal Revenue Code "Low Income Housing Credit" Law, and for which the cost of rehabilitation has not been less than ten thousand dollars ($10,000.00) per unit rehabilitated, or for any dwelling unit or units in an "R-3" Multiple-Family Dwelling District located within six hundred (600) feet of an interstate highway, said unit or units located in said district may be reconstructed after damage by fire, explosion or act of God to the extent of the same density and configuration as existed prior to said casualty, regardless of the extent of the damage within eighteen (18) months of the eligible loss. In such instance, all regulations of this Chapter shall be complied with, except that there need not be compliance with the lot area requirements set forth in Section 400.250(D), so that all damaged units may be reconstructed as they existed prior to the casualty.

No existing building or premises devoted to a use not permitted by this Chapter in the district in which such building or premises is located, except when required to do so by law or ordinance, shall be enlarged, extended, reconstructed or structurally altered, unless such use is changed to one permitted in the district in which such building or premises is located.

Any building or land used in whole or part for a use listed as a special use in the district in which it is located that is proposed to be enlarged, extended, relocated or altered shall be required to obtain a special use permit in accord with the terms of this Chapter.

Any non-conforming use of land or of a building which becomes vacant for a period of one (1) year or more shall lose its non-conforming status and may then only be used in compliance with the current zoning district regulations governing the district in which it is located.