The lawful and substantial use of any building or land existing as of the second day of March 1971 may be continued although such use does not conform to the provisions of this chapter.

Any structure or portion thereof declared unsafe by a proper authority may be restored to a safe condition.

A nonconforming building may not be reconstructed or structurally altered during its life without the consent of the ZBA, except that a building that is nonconforming because of minimum lot size or nonconforming yard dimensions may be reconstructed or structurally altered in a manner which does not further encroach on a required yard dimension.

The extension of a legal nonconforming use shall be allowed by the ZBA only upon the granting of a special permit pursuant to § 197-61 of this chapter and any rules and regulations promulgated thereunder.

If a building is damaged or destroyed by fire or other causes, the same may be rebuilt and restored within one year from the date of destruction; however, such building or restoration shall be limited to the size of the building destroyed, and the reconstruction and restoration of said building shall be of the same character as the original building, and the use to which said building shall be put shall be to the same use as the prior nonconforming use.

Whenever a nonconforming use has been discontinued for a period of one year or more, such use shall be reestablished only upon the granting of a use variance by the ZBA pursuant to § 197-59 of this chapter and any rules and regulations promulgated thereunder.

Once changed to a conforming use, no building or land shall be permitted to revert to a nonconforming use. A nonconforming use may be changed to a use of the same or higher classification, and such use thereafter shall not be changed to a lower classification.

No nonconforming use shall be extended to displace a conforming use.