ADU rules in Greenville County

In zoned unincorporated Greenville County a detached accessory dwelling is allowed only in the AG, Agricultural Preservation District, whose minimum lot area is 5 acres: Table 6.1 lists 'Dwelling - accessory' as C9 in AG, and condition 9(B) allows 'only one detached accessory dwelling unit' with a principal dwelling there. No single-family residential district (R-R3, R-R1, R-S, R-20 through R-6, R-20A, ESD-PM) lists the use. The only route on an ordinary residential lot is a temporary accessory dwelling under Section 11:9: a manufactured home approved by the Board of Zoning Appeals as a special exception for a relative needing continuous nursing care, renewed yearly and removed when the hardship ends. The 2024 Unified Development Ordinance that would have opened ADUs more widely was reconsidered in January 2025 and never took effect, so the 2005 Zoning Ordinance governs.

The Zoning Ordinance has no attached or internal ADU for houses in residential districts. Condition 9(A) allows one accessory dwelling inside the structure of a permitted nonresidential use in the O-D, C-1, C-2 and C-3 districts (a caretaker-type unit 'necessary to the operation of the permitted principal use'), and condition 9(B) in AG covers detached units only. The nearest by-right path to a second unit in a house is a two-family dwelling: a duplex is permitted on an existing lot of record in R-6, R-7.5 and R-10 if it meets the single-family district standards (condition 10(B), amended by Ord. 5807 of 9-15-2026), and outright in the R-M multifamily districts. Following the directory convention for codes without an attached ADU use, this is recorded as conditional with low confidence.

Condition 9(B)(1) caps an AG accessory dwelling at 50 percent of the primary dwelling's gross square footage. It must sit in the side or rear yard, meet the AG setbacks in Tables 7.1 and 7.3, meet state health (septic and well) rules, and share the primary dwelling's driveway; a manufactured home used as the ADU must meet the manufactured-house conditions in condition 11. There is no separate height limit for the ADU beyond the district standards. In unzoned areas the Land Development Regulations allow ADUs of up to 800 square feet of living space only inside a Traditional Neighborhood Development (Section 13.3.2(F)).

Condition 9 sets no owner-occupancy requirement for an AG accessory dwelling or for a caretaker unit in a nonresidential district; the ordinance's only owner-residence rule in this area is condition 4(L) for bed and breakfasts. The temporary accessory dwelling under Section 11:9 is tied to the medical need of the person living in it rather than to ownership. South Carolina has no state ADU law that adds or forbids an owner-occupancy rule.

Table 12.1 has no line for accessory dwellings: it requires two spaces for a single-family detached dwelling and two spaces per unit for a two-family dwelling. Section 12:2 requires parking 'in the amount specified by this section' when dwelling units are added, and no amount is specified for an accessory dwelling, so no extra space is listed. Condition 9(B)(5) requires the AG accessory dwelling to share a driveway with the primary dwelling.

A 'C' use in Table 6.1 is 'permitted in the respective zoning district only if it complies with use-specific conditions' (Section 6:1.2), which Zoning Administration checks at permit review, so an AG accessory dwelling or a duplex on a qualifying R-6 to R-10 lot needs a zoning and building permit with no hearing. The temporary accessory dwelling (Section 11:9) is the exception: it is an 'SE' use needing a Board of Zoning Appeals special exception hearing, with yearly renewal by the Zoning Administrator. In unzoned areas only the Land Development Regulations and the building code apply.

Condition 9 does not restrict who may occupy or rent an AG accessory dwelling, and nothing bars a long-term rental of it. By definition, 'accessory living quarters' (a guest house without a kitchen) may not be rented, and a temporary accessory dwelling may only house the person with the medical hardship. Unincorporated Greenville County had no short-term rental ordinance at 2026-10-17: a Short Term Rentals Ad Hoc Committee is working on a draft registration ordinance (August 12, 2026 draft) that would allow STRs in any legally existing dwelling unit, require yearly registration, and allow room rentals only in the operator's primary residence while the operator is present. The state 2 percent accommodations tax and the county local accommodations fee apply to stays under 90 days.