ADU rules in Greenville

Greenville's Development Code (Chapter 19) lists 'Accessory dwelling unit' as P* (allowed with Administrator approval subject to use standards) in all four House-Scale districts, RH-A, RH-B, RH-C and RH-D, which are the city's single-family districts, each allowing 1 primary unit and 1 accessory unit per lot. Sec. 19-2.11.3.A.3.c says ADUs 'may be detached or attached to the primary dwelling unit.' The ADU row is blank (not allowed as a listed use) in every other district; the Neighborhood-Scale (RN-, RNX-) districts instead allow up to 4 primary dwelling units per lot outright.

Attached and internal ADUs are allowed on the same terms as detached ones in RH-A to RH-D. The Single-Unit Living definition says the use 'May include one accessory dwelling unit on the same lot that is detached, attached, or internal to the principal structure,' and §19-2.11.3 lets ADUs be detached or attached. A wet bar or partial kitchen without a range or 220V circuit does not count as cooking facilities, so a guest suite without those is not an ADU.

Sec. 19-3.5.2.A.5 limits an ADU's square footage to 80 percent of the primary dwelling, up to a maximum of 1,000 square feet. The ADU must also meet all district standards including setbacks, height, massing, side wall height and building coverage. Accessory structures may be 2 stories and 25 feet tall in RH-A and 2 stories and 20 feet in RH-B, RH-C and RH-D, with an 18 foot side wall cap in RH-A. Building coverage caps run from 20 percent in RH-A upward by lot size, and rooftop or second-story decks must face the lot interior.

Owner occupancy is an ongoing condition: to establish and maintain an ADU, the owner of the lot must occupy either the principal dwelling or the ADU as their primary residence. South Carolina has no state ADU statute, so this local rule controls.

The vehicle parking table requires 2 spaces per primary unit plus 1 per accessory unit for single-unit living. Minimum parking does not apply to lots in the MX-D or MXS-D districts, lots in a Preservation (-P) overlay, lots with a local Landmark historic property, or lots with a building on the Historic Resources List or the National Register. Sec. 19-4.6.2 also allows parking reductions through alternatives and a change of up to 10 percent under Sec. 6.2.14.

The use table key defines P* as 'A use allowed with approval of the Administrator, provided it meets the use standards'; ADUs are P* in RH-A to RH-D, so review is administrative (staff zoning and building permits), not a Board of Zoning Appeals hearing. A permit is required for any accessory structure over 100 square feet, and the Administrator may require a transition screen (L-1, M-1 or M-2) when approving an ADU. Under S.C. Code §6-29-1145, the city will not issue a zoning or building permit for an ADU when it has notice of a recorded restrictive covenant prohibiting the use.

Sec. 19-3.5.2.A.8 says an ADU 'may be rented but cannot be sold separately from the primary dwelling,' and short-term rental use is only permitted as provided in the use table. Short-term rentals fall in the General Lodging use (stays generally under 30 days), which the use table bars ('-') in every RH and RN district and allows (P*) only in mixed-use, shopfront, business, IX and CM districts. Because ADUs are only allowed in RH districts, an ADU cannot be used as a short-term rental. Owner occupancy of one of the two units still applies to a long-term rental.