Where a lawful structure exists at the effective date of amendment of this Zoning Regulation that could not be built under the terms of this Zoning Regulation by reason of restrictions on area, lot coverage, height, yards, its location on the lot, bulk, or other, as long as it remains otherwise lawful, is subject to the following provisions:
   (a)   Enlargement or Alteration:  No such non-conforming structure may be enlarged or altered in any way which increases its non-conformity, but any structure or portion thereof may be altered to decrease its non-conformity.
   (b)   Destruction:  Should such non-conforming structure or non-conforming portion of structure be destroyed by any means, to an extent of more than sixty percent (60%) of its replacement cost at the time of destruction, it shall not be reconstructed except in conformity with the provisions of this Zoning Regulation.
   (c)   Restoration:  When a building or structure, the use of which does not conform to the provisions of this Regulation, has been damaged by explosion, fire, or Act of God, to the extent of sixty percent (60%) or more of its reproduction value at the time of damage, it shall not be restored or reconstructed or in any way be used except in conformity with the district regulations of the district in which the building is situated.
   (d)   Moving of Structure:  Should a non-conforming structure be moved for any distance whatsoever, it shall thereafter conform to the regulations for the district in which it is located after it is moved.
   (e)   Repairs and Maintenance:   On any non-conforming structure or portion of such a structure or a portion of a structure that contains a non-conforming use, ordinary repair or repair or replacement of non-weight bearing walls, fixtures, wiring, or plumbing may be performed provided that the cubic content existing when it became non-conforming shall not be increased. Nothing in this section 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 protection the public safety, upon such an order.
   (f)   Beginning of Construction: To avoid undue Zoning Regulation shall be deemed to require a change in the plans, construction or designated use of any building on which actual construction was lawfully begun and has been diligently carried on prior to the effective date of adoption or amendment of this Zoning Regulation. Actual construction is hereby defined to include the placing of construction materials in permanent position and fastened in a permanent manner; except that where demolition or removal of an existing building has been substantially begun preparatory torebuilding, such demolition or removal shall be deemed to be actual construction, provided that work shall be diligently carried on until completion of the building involved.