S.C. Code Ann. § 4-25-210: Building permit required.

It shall be unlawful for any person to erect or construct any improvements on real estate, which cost in excess of one thousand dollars, in any county containing a municipality with a population of more than ninety-seven thousand, according to the latest official United States census, unless an application has been filed with and a permit granted by the county auditor to erect or construct such improvements; provided, that no application or permit shall be required for such improvements upon real estate situate within any incorporated municipality, which requires a permit for the erection or construction of such improvements.