The lawful use of a building 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 nonconforming use of a building may be changed to another nonconforming use of the same or more restricted classification. Whenever a nonconforming use has been changed to a more restricted use or to a conforming use, such use shall not thereafter be changed to a less restricted one. Whenever the use of a building becomes nonconforming through a change in the zoning ordinance or district boundaries, such use may be continued and, if no structural alterations are made, it may be changed to another nonconforming use of the same or of a more restricted classification.

Whenever a nonconforming use of a property, building, sign or part thereof has been discontinued for a period of 12 consecutive months, said nonconforming use shall be presumed to be abandoned, and the use of the premises thereafter shall be in conformance with the regulations of the district.

No existing building or premises devoted to a use not permitted in the district in which such building or premises is located shall be enlarged, extended, reconstructed or structurally altered unless such use is changed to a use permitted in the district in which such building or premises is located except when approved by the Zoning Hearing Board.

Any building or structure containing a nonconforming use which is damaged by fire, flood, wind or other act of God or man to the extent of 75% or more of its fair market value immediately prior to damage shall not be repaired or reconstructed except in a manner which will not be detrimental to the character of the neighborhood. In the event that the Zoning Officer's estimate of the extent of damage of fair market value is not acceptable to the applicant for the building permit to repair or reconstruct such building or structure, the applicant may appeal to the Zoning Hearing Board.

No building or structure designed or intended to be utilized for a nonconforming use shall be constructed or allowed unless construction is already underway at the time of the enactment or subsequent amendment of this chapter and is being diligently prosecuted so that such building or structure will be completed within 18 months from the time of the enactment or subsequent amendment of this chapter. All outstanding building permits for construction which does not meet those requirements are hereby rendered null and void. Said structure must be completed before a certificate of occupancy is granted (§ 155-50).

The provisions of this article shall not apply to any building or structure which is designated by the Planning Commission, with concurrence of the Township Commissioners, to be a historical landmark.