Within the districts established by this chapter or amendments that may later be adopted there exist lots, structures and uses of land and structures which were lawful before this chapter was passed or amended, but which would be prohibited under the terms of this chapter or future amendment, it is the intent of this chapter to permit these nonconformities to continue until they are removed. Such uses are declared by this chapter to be incompatible with permitted uses in the districts involved. Nonconformities may be enlarged and expanded only by the approval of the Zoning Hearing Board. Any enlargements or expansions approved by the Zoning Hearing Board shall meet the provisions of use for that type of use. Nonconforming industrial uses shall meet the provisions of use for the Industrial District, and likewise any nonconforming commercial uses shall meet the provisions of use requirements for the Business District when they are either enlarged or expanded.

A nonconforming use of a structure, a nonconforming use of land or nonconforming use of a structure and land shall not be extended or enlarged after passage of this chapter by attachment of additional signs to a building, or the placement of additional signs or display devices on the land outside the building, or by the addition of other uses, if such additions are of a nature which would be prohibited generally in the district involved.

Nothing in this chapter shall be deemed to require a change in the plans, construction or designated use of any building on which actual construction was lawfully begun prior to the effective date of adoption or amendment of this chapter and upon which actual building construction has been diligently carried on. "Actual construction" is defined to include the placing of construction materials in permanent position and fastened in a permanent manner, and demolition, elimination and removal of an existing structure in connection with such construction, provided that actual construction work shall be diligently carried on until the completion of the building involved.

In any district in which single-family dwellings are permitted, notwithstanding limitations imposed by other provisions of this chapter, a single-family dwelling and customary accessory buildings may be erected on any single lot of record at the effective date of adoption or amendment of this chapter. Such lot must be in separate ownership and not of continuous frontage with other lots in the same ownership. This provision shall apply even though such lots fails to meet the requirements for area or width, or both, that are applicable in the district, provided that yard dimensions and other requirements not involving area or width, or both, of lot shall conform to the regulations for the district in which such lot is located. Variance of yard requirements and other requirements not involving area or width, or both, of lot shall be obtained only through action of the Zoning Hearing Board.

If two or more lots or combinations of lots and portions of lots with continuous frontage in single ownership are of record at the time of passage or amendment of this chapter, and if all or part of the lots do not meet the requirements for lot width and area in the respective district, the lands involved shall be considered to be an undivided parcel for the purpose of this chapter, and no portion of said parcel shall be used or sold which does not meet lot width and area requirements established by this chapter, nor shall any division of the parcel be made which leaves remaining any lot with width or area below the requirements stated in this chapter.

No such nonconforming use shall be enlarged or increased, nor extended to occupy a greater area of land than was occupied at the effective date of adoption or amendment of this chapter, except as specified by § 550-47 of this chapter.

No such nonconforming use shall be moved in whole or in part to any other portion of the lot or parcel occupied by such use at the effective date of adoption or amendment of this chapter.

If any such nonconforming use of land ceases for any reason for a period of more than 12 consecutive months, any subsequent use of such land shall conform to the regulations specified by this chapter for the district in which such land is located.

A structure may be enlarged or altered in a reasonable amount only as approved by the Zoning Hearing Board.

Should such structure be destroyed by any means to an extent of more than 50% of its replacement cost at time of destruction, it shall not be reconstructed except in conformity with the provisions of this chapter unless a variance is granted by the Zoning Hearing Board.

Should such structure be moved for any reason for any distance whatever, it shall thereafter conform to the regulations for the district in which it is located after moved.

An existing structure devoted to a use not permitted by this chapter in the district in which it is located may be enlarged, extended, constructed, reconstructed or structurally altered to any reasonable amount upon granting of a variance by the Zoning Hearing Board. Any enlargements or expansions approved by the Zoning Hearing Board shall meet the provisions of use for that type of use. Nonconforming industrial structures shall meet the provisions of use for the Industrial District, and likewise, any nonconforming commercial structures meet the provisions of use requirements for the Business District when they are either enlarged, extended, constructed, reconstructed or structurally altered.

Any nonconforming use may be extended throughout any parts of a building which were manifestly arranged or designed for such use at the time of adoption or amendment of this chapter, but no such use shall be extended to occupy any land outside such building.

If no structural alterations are made, any nonconforming use of a structure or structure and premises may be changed to another nonconforming use, provided that the Zoning Hearing Board, either by general rule or by making findings in the specific case, shall find that the proposed use is equally appropriate or more appropriate to the district than the existing nonconforming use. In permitting such change, the Zoning Hearing Board may require appropriate conditions and safeguards in accord with the provisions of this chapter.

Any structure, or structure and land in combination, in or on which a nonconforming use is superseded by a permitted use, shall thereafter conform to the regulations for the district in which such structure is located, and the nonconforming use may not thereafter be resumed.

When a nonconforming use of a structure, or structure and premises in combination, is discontinued or abandoned for 12 consecutive months, the structure and premises in combination, shall not thereafter be used except in conformance with the regulations of the district in which it is located.

Where nonconforming use status applies to a structure and premises in combination, removal or destruction of the structure shall eliminate the nonconforming status of the land.

Notwithstanding any other provisions pertaining to nonconforming uses in this chapter, an existing nonconforming residential dwelling destroyed in whole or in part by fire, flood, explosion or any other casualty beyond the control of the property owner, may be reconstructed and used as before said casualty, provided:

Notwithstanding any other provisions pertaining to nonconforming uses in this chapter, an existing nonconforming residential dwelling or any of its customarily accessory structure may be expanded in floor area up to an additional 25% each of the existing floor area, provided:

On any building, devoted in whole or in part to any nonconforming use, work may be done on ordinary repairs or on repair or replacement of nonbearing walls, fixtures, wiring or plumbing with the normal permitting process.

Nothing in this chapter shall be deemed to prevent the strengthening or restoring to a safe condition of any building or part thereof declared to be unsafe by any official charged with protecting the public safety, upon order of such official.