Where a lawful structure exists at the effective date of adoption or amendment of this Code that could not be built under the terms of this Code by reason of restrictions on lot area, lot coverage, height, yards, its location on the lot, or other require ments concerning the structure, such structure may be continued so long as it remains otherwise lawful, subject to the following provisions:
(a) Enlarged. Any nonconforming structure or portion thereof may be enlarged or altered if the nonconformity is not increased. No such nonconforming structure may be enlarged or altered in a way which increases its nonconformity.
(b) Destruction. When a nonconforming structure is destroyed by any means to the extent of more than fifty (50) percent of the cost of replacement of such structure, as determined by a third party appraisal, it shall not be rebuilt, restored, or reoccupied for any use unless it conforms to all regulations of this Code.
(c) Moved. 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 it is moved.
(d) Single Family Dwellings. The limitations on enlarging, rebuilding and moving nonconforming structures in subsections (a)-(c) above shall not apply to single family dwellings located in residential zoning districts. A nonconforming single family dwelling located in a residential zoning district may be enlarged, rebuilt or moved within the setback limits otherwise established for that district.