S.C. Code Ann. § 6-29-730: Nonconformities.

The regulations may provide that land, buildings, and structures and the uses of them which are lawful at the time of the enactment or amendment of zoning regulations may be continued although not in conformity with the regulations or amendments, which is called a nonconformity. The governing authority of a municipality or county may provide in the zoning ordinance or resolution for the continuance, restoration, reconstruction, extension, or substitution of nonconformities. The governing authority also may provide for the termination of a nonconformity by specifying the period or periods in which the nonconformity is required to cease or be brought into conformance, or by providing a formula where the compulsory termination of nonconformities may be so fixed as to allow for the recovery or amortization of the investment in the nonconformity.