Any lawful nonconforming use or structure existing at the time of the passage of this chapter may be continued upon the lot or in the structure so occupied, and any such structure may be restored or repaired in the event of partial destruction thereof. The nonconforming use of a conforming or a nonconforming structure shall not be expanded, increased or enlarged. A nonconforming structure designed, arranged or devoted to a nonconforming use shall not be structurally enlarged unless the structure is changed to a conforming structure, and provided that the nonconforming use thereof is neither expanded, increased or enlarged. A nonconforming structure which complies with the use requirements of this chapter and is nonconforming because of height, area or yard regulations may be enlarged, provided that the height, area or yard regulations are not further violated.

A nonconforming use in existence at the time of the passage of this chapter shall not be permitted to be changed to any use other than a conforming use.

In the event that there is a cessation of operation of any nonconforming use for a period of 12 consecutive calendar months for any reason other than a national emergency or act of God, the same shall be deemed to be an abandonment of such nonconforming use. Any subsequent exercise of such abandoned nonconforming use shall be deemed a violation of the terms of this chapter.

Nothing in this chapter shall require any change in plans, construction or designated use of a structure for which a building permit has been lawfully heretofore issued when construction has been diligently prosecuted within six months of the date of issuance of such permit.

A building permit for the reconstruction of any nonconforming use must be applied for within 12 months from the time of partial destruction. Nothing in this chapter shall prevent the restoration of a structure declared unsafe by any governmental authority.

The forgoing provisions of this article shall also apply to building structures, land or uses which hereafter become nonconforming due to any reclassification of zone districts under this chapter or any subsequent change in the regulations of this chapter.

Nothing in this chapter shall be interpreted as authorization for or approval of the continuance of the use of a structure or premises in violation of zoning regulations in effect at the time of the effective date of this chapter.