Subject to the provisions of this section, a use of building or land existing at the time of the enactment of this chapter may be continued even though such use does not conform with the provisions of these regulations for the district in which it is located.

Nothing in this chapter shall prevent the strengthening or restoring to a safe condition of any portion of a building or structure declared unsafe by a proper authority.

A nonconforming structure may be increased in height not to exceed the maximum height of the respective district. A nonconforming structure may be expanded into an a required yard as long as such expansion does not encroach further into the yard and does not increase the footprint of the building as existing at the time of passage of this chapter more than 25%. The Zoning Officer shall keep a written log of permit issuances for the expansion of nonconforming structures such that this provision may be properly enforced.

Nothing in this chapter shall prevent the reconstruction, repairing, rebuilding and continued use of any nonconforming building or structure damaged by fire, collapse, explosion or act of God, excepting demolition specified in § 280-1308, subsequent to the date of this chapter nor shall it prevent the regular maintenance of a nonconforming structure including the replacement of a roof, exterior facade, windows, and other treatments.

A nonconforming use shall not be extended, except as authorized by special exception pursuant to Article XI, but the extension of a lawful use to any portion of a nonconforming building or structure that existed prior to the enactment of the Ordinance shall not be deemed the extension of such nonconforming use.

No nonconforming building, structure, or use shall be changed to another nonconforming use unless approved by the Zoning Hearing Board as a special exception pursuant to Article XI.

Nothing herein contained shall require any change in plans, construction or designated use of a building or structure for which a zoning permit has been issued and the construction of which shall have been diligently prosecuted within two months of the date of such permit and the ground story framework of which shall have been completed within four months of the date of the permit, and which entire building shall be completed according to such plans as filed within one year from the date of this chapter.

Where 50% or more of the floor area of a nonconforming structure is demolished by fire, accident, vandalism, or act of God and the owner receives an insurance settlement in an amount equal to the fair market value of the demolished building or portion thereof, and where nonconforming buildings are voluntarily demolished, any future building on the site shall comply with the following. Lots with demolished residential dwelling units and accessory structures thereto may include the construction of a building within some or the entire footprint of the demolished building at the time of its demolition within 18 months of such. Lots bearing demolished commercial and other principal structures and structures accessory thereto shall be subject to all existing requirements of this chapter.

Any nonconforming sign removed, whether by Act of God, vandalism, accident, or voluntarily, if replaced, shall be subject to all existing standards of this chapter.

A nonconforming use of a building or land that has been abandoned shall not thereafter be returned to such nonconforming use. A nonconforming use shall be considered abandoned as follows:

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.

Whenever the boundaries of a district shall be changed so as to transfer an area from one district to another district of a different classification, the foregoing provisions shall apply to any nonconforming uses existing therein.