A nonconforming building or structure can be altered, extended or enlarged only if such alteration, extension or enlargement does not increase the existing nonconformity.

A nonconforming use may be continued although such use does not conform to the provisions of this chapter, and such use may be extended throughout the premises lawfully acquired previous to the adoption of the chapter or any amendment to this chapter, provided that such extension of use is in conformity with the provisions of this chapter.

A nonconforming use of a building or premises may be changed to a use of the same or higher classification according to the provisions of this chapter.

Whenever a district shall hereafter be changed, any then-existing nonconforming use of a building or premises in such changed district may be continued or changed to a use of the same or higher classification, provided that there is compliance with all other regulations governing the new use.

Whenever a nonconforming use of a building or premises has been abandoned or changed to a higher classification or to a conforming use, such use shall not thereafter be changed to a use of any other classification unless so zoned.

Discontinuance of any nonconforming use for a period of one year or more terminates such nonconforming use of a structure or premises, and, thereafter, said structure or premises shall not be used except in conformity with the provisions of the chapter.

Any lot held in single and separate fee ownership upon which a building could be legally erected (i.e., a legally buildable lot) on the date of the enactment of this chapter but which is no longer legally buildable because of the size, width or depth requirements of this chapter shall continue to be a legally buildable lot, subject to the provisions of this chapter, with the exception of such size, width or depth dimensions as shall have been substandard at the time of enactment of this chapter.

In the case of any lot which is substandard in area by the terms of this chapter but was once legally buildable and thereafter singly and separately held in fee ownership, the rights acquired or existing therein for the use of said lot as a legally buildable lot shall terminate and become nonexistent and void should said substandard lot merge in fee with any adjoining land or property, thereby creating a larger lot, whether or not such larger lot conforms to the area requirements of this chapter, or thereby enlarging an adjoining lot already conforming to such requirements. Such merger shall be deemed to occur when the same person or persons acquire, obtain or have fee ownership in both lots, whether by purchase, sale, devise, gift or otherwise.