A non-conforming structure may be restored regardless of other regulations in this Zoning Ordinance subject to the following limitations enumerated below.
   A.    Structure Declared Unsafe.  The structure has been declared unsafe by the Commissioner of Buildings or other authorized administrative official.
   B.    Structure Damaged or Destroyed.  At least sixty percent (60%) of the structure, according to the determination of the Building Commissioner, has been partly destroyed or removed by whatever cause including Acts of God, with the exception that single-family, two-family and duplex dwellings may be restored for such use in accordance with this Zoning Ordinance without limitation as to cost.