S.C. Code Ann. § 6-9-130: Codes applicable to building inspections.

(A) Buildings must be inspected in accordance with the codes in effect for the locality on the date of the issuance of the original building permit, except that:

(1) If no date of issuance of original building permit can be found, the date of submission of the completed application to the local authority must be used.

(2) If no date of application for, or date of issuance of, building permit is available, the director of the applicable county planning and development service (or similar agency) shall determine the nearest possible date by using available documents, such as transfer of property records, mortgage records, tax records, or rent records.

(B) A building inspection conducted in conjunction with any change in structure must be performed in accordance with the applicable code in effect on date of application or date of permit.

(C) A building inspection conducted in conjunction with a change of use for the building or space must be performed in accordance with the applicable code in effect on the date of the inspection. This inspection should be done with the intention of avoiding extreme hardship to the owner whenever practical.