Horry County, SC Accessory Structures: ADU Rules (2026)

Unincorporated Horry County regulates ADUs under Appendix B (Zoning Ordinance), Section 925 - Accessory Dwelling Units. ADUs may be located either within an existing principal dwelling or in a separate detached structure, but they are a conditional use rather than a use by right, meaning each application must be reviewed and approved through the conditional-use process. ADUs are permitted in every zoning district that allows a single-family detached principal dwelling, including RE (Rural Estates), SF, and other residential districts. Three core requirements apply: (1) the principal dwelling must be occupied by the property owner, (2) no more than one ADU is allowed per parcel, and (3) the minimum lot area must be at least two times the normal minimum lot size for the underlying district. For detached ADUs, the structure must be set back at least 20 feet from the principal dwelling, and detached ADUs are limited to a maximum of 1,000 square feet of heated floor area. The county's online application packet requires a Notarized Authorization Letter from the property owner. Note: South Carolina has not enacted the proposed statewide ADU Affordable Housing Incentive Act (H.3469, 2025-2026 session); even if adopted, that bill explicitly defers to local zoning, so Horry County's Section 925 standards remain controlling.