ADU rules in Horry County, SC β also called accessory dwelling unit regulations or granny flat ordinances β cover setbacks, owner-occupancy, parking, and permit requirements.
Horry County allows accessory dwelling units (ADUs) as a conditional use in every zoning district where a principal single-family detached dwelling is permitted. Section 925 of Appendix B (Zoning Ordinance) caps detached ADUs at 1,000 square feet, requires the principal dwelling to be owner-occupied, doubles the minimum lot area, and requires at least 20 feet of separation between the principal dwelling and a detached ADU. Only one ADU is allowed per parcel.
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.
Operating an ADU without conditional-use approval, exceeding the 1,000 sq ft cap, failing to maintain owner occupancy of the principal dwelling, or building a second ADU on a parcel constitutes a zoning violation. Horry County Code Enforcement may issue stop-work orders, withhold or revoke certificates of occupancy, and pursue civil penalties under the general zoning enforcement provisions of Appendix B and Title 6 of the South Carolina Code.
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See how Horry County's adu rules rules stack up against other locations.
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