No existing building or premises devoted to the use not permitted by this Chapter in the district in which such building or premises is located shall be extended, reconstructed or structurally altered unless such use is changed in accordance with this Article, except when required to do so by law or order. Further, extension of non-conforming uses or structures which, in the determination of the Building Commissioner, constitute over twenty-five percent (25%) of the area occupied by the original use or structure shall require conformance of the entire use or structure with this Chapter.

The lawful use of a building on land existing at the time of the effective date of this Chapter may be continued although such use does not conform to the provisions hereof. If no structural alterations are made, a non-conforming use of a building may be changed to another non-conforming use of the same or of a more restrictive classification. Whenever a non-conforming use has been changed to a more restrictive classification or to a conforming use, such use shall not thereafter be changed to a less restrictive use.

Whenever the use of a building becomes non-conforming through a change in the zoning ordinance or district boundaries, such use may be continued and if no structural alterations are made, may be changed to another non-conforming use of a more restrictive classification.

In the event that a non-conforming use of any building or premises is voluntarily discontinued for a period of one (1) year, the use of the same shall thereafter conform to the use permitted in the district in which it is located.

When a building, the use of which does not conform to the provisions of this Chapter, is damaged by fire, explosion, act of God or the public enemy to the extent of more than sixty percent (60%) of its original structure, as determined by the Building Commissioner, it shall not be restored except in conformity with the district regulations of the district in which the building is situated.