The State of South Carolina adopted the International Code Council Building Codes. Some areas in South Carolina, particularly Aiken and Horry County are allowing Tiny Houses with restrictions on where they can be placed.
Beaufort SC allows Accessory Dwelling Units, however, they must be at least 240 Square Feet. Refer in particular to Section 5.3B Below.
Laurens County, South Carolina Building Codes
City of West Columbia, South Carolina Approves Tiny House Village
If you would like to review regulations for another state, click here