Simpsonville, SC Accessory Structures: ADU Rules (2026)

Greenville County's zoning framework is administered through the Greenville County Zoning Ordinance (Chapter 4 of the County Code of Ordinances), which establishes residential districts ranging from R-S (suburban) and R-7.5, R-10, R-12, R-15, R-20 (single-family, by minimum lot size) up through R-M series multi-family districts and mixed-use overlays. Permitted uses by district are listed in Use Table 6.1 of the ordinance. Under that framework, a single-family residential district allows only one principal dwelling unit per lot; an additional, separately accessible apartment for a second household is not among the permitted uses.

The County's public-facing Zoning AnswerBook — published by Greenville County Code Enforcement at greenvillecounty.org/AnswerBook/zoning.aspx — sets out the everyday rules for property owners in those districts and states explicitly that, in single-family residential districts, "converting a basement or garage into a separate apartment is prohibited." The same AnswerBook lists the other accessory-structure rules: detached garages, sheds, swimming pools, and game courts must be located in rear yards; unlicensed vehicles may not be stored outdoors; livestock are prohibited except in R-S districts; and home-based businesses are restricted to a use that does not change the residential character of the dwelling.

The practical effect is that a Greenville County homeowner in a typical single-family district cannot legally build, convert, or rent out a detached "granny flat," in-law suite with a separate kitchen and entrance, basement apartment, or garage-conversion apartment as a separately rentable dwelling unit. The dwelling may contain additional bedrooms, a finished basement used as part of the household, or a home office, but it cannot be partitioned into a second independent dwelling unit. An "accessory apartment" that does not include its own kitchen — i.e., is functionally part of the principal dwelling — is not the prohibited use, but a second kitchen creating a separate household is.

A property owner who wants an additional dwelling unit on the property has a limited set of legal paths: (1) own land that is already zoned in a multi-family or mixed-use district (R-M, R-M-15, R-M-20, etc., per Use Table 6.1); (2) apply for a zoning map amendment (rezoning) to the County Council, with Planning Commission review; (3) for a property in an unincorporated community center or activity hub, evaluate whether a Planned Development (PD) overlay or other special district allows the desired use; or (4) annex into a city that has a more permissive ADU ordinance. Contact Zoning Administration at 301 University Ridge, Suite S-3200, Greenville, SC 29601, phone (864) 467-7425, email zoning@greenvillecounty.org, before pursuing any of these options.

Note: Cities inside Greenville County (Greenville, Greer, Mauldin, Simpsonville, Fountain Inn, Travelers Rest) operate under their own city zoning ordinances and may permit ADUs under different conditions. The County's ADU prohibition described here applies only to unincorporated Greenville County. South Carolina has no statewide statute mandating local ADU approvals (unlike California, Oregon, or Washington), so local zoning controls.