Lawful nonconforming uses existing at the time of the enactment of this chapter or any amendment thereto may be continued subject to the following provisions.
(A) A nonconforming use shall not be changed to any but a conforming use. When a nonconforming use has been changed to conforming use, it shall not be changed again to any nonconforming use.
(B) A nonconforming use of a building or buildings shall not be materially expanded in its scope or extended to include either additional land or buildings after the enactment or subsequent amendment of this chapter.
(C) Normal maintenance or alteration may be performed on nonconforming structures.
(D) When a nonconforming use of building, structure or land has been discontinued for a period of 60 consecutive months, it shall not be re-established or changed to any use not in conformity with the provisions of the district in which it is located. Non-operative status or vacating of the premises or building shall be evidence of a discontinued use. Sixty consecutive months shall constitute the irrefutable presumption of voluntary discontinued use.
(E) 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 the 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 these requirements shall be rendered null and void by the enactment or subsequent amendment of this chapter.
(2000 Code, App. B, § 33)