Rock Hill, SC Accessory Structures: ADU Rules (2026)

South Carolina grants planning and zoning authority to municipalities through the Local Government Comprehensive Planning Enabling Act of 1994, codified at S.C. Code §6-29-310 et seq. The Act authorizes adoption of comprehensive plans (§6-29-510), creation of local planning commissions (§6-29-340), zoning ordinances (§6-29-720), and boards of zoning appeals (§6-29-780). Rock Hill exercises this authority through Chapter 31 of its Code of Ordinances, which is the city's zoning ordinance and is hosted on Municode along with the rest of the Code. Chapter 31 divides the city into residential districts (typically single-family, two-family, and multi-family categories) plus commercial, industrial, and mixed-use districts. Whether an ADU is permitted in a given district, whether it must be attached or may be detached, minimum and maximum unit size, off-street parking requirements, owner-occupancy obligations, and any rental restrictions are all set by Chapter 31. The Rock Hill Planning Commission, established under S.C. Code §6-29-340, hears special exception applications referred to it and makes recommendations on zoning amendments to City Council. The Board of Zoning Appeals hears variances and special exceptions under S.C. Code §6-29-790. Because South Carolina has not enacted ADU preemption, there is no statutory ministerial-approval requirement, no state-mandated unit size minimum, and no statewide ban on owner-occupancy or rental restrictions. Property owners should consult Chapter 31 and the Rock Hill Planning and Development Department for a written zoning determination before designing an ADU. Building construction must additionally comply with the South Carolina-adopted International Residential Code under S.C. Code §6-9-50 (state building codes), which makes the IRC/IBC mandatory minimums for South Carolina municipalities.