Aiken County, SC Accessory Structures: ADU Rules (2026)
ADU rules in Aiken County, SC, also called accessory dwelling unit regulations or granny flat ordinances, cover setbacks, owner-occupancy, parking, and permit requirements.
Key Facts
- Size cap
- 50% of main house or 1,300 sq ft
- Bedroom limit
- 2 bedrooms maximum
- Per lot
- 1 accessory apartment, owner-occupied only
- RC district
- 2-acre minimum lot required
- Detached setback
- 20 ft from principal dwelling
Summary
Aiken County permits one accessory apartment per single-family, owner-occupied lot as a conditional use under Table 1. The unit cannot exceed 50 percent of the main house's floor area or 1,300 square feet, whichever is smaller, and cannot contain more than two bedrooms.
Accessory apartments, where permitted by Table 1 as conditional uses, shall meet the following conditions:(1)The apartment, whether attached or detached, cannot exceed fifty (50) percent gross floor area of the principal dwelling or one thousand three hundred (1,300) feet, whichever is less, or contain more than two (2) bedrooms;(2)The apartment must be a complete living space, with kitchen and bathroom facilities separated from the principal unit;(4)An accessory apartment may be accessory only to a single-family owner-occupied dwelling, and not more than one (1) apartment shall be allowed per dwelling lot;
Official source re-checked September 7, 2026: no newer edition of the code had been published (publisher’s edition: Code of Ordinances: Supplement 119).
Full Breakdown
Sec. 17 sets seven conditions for accessory apartments allowed as conditional uses under Table 1. Clause (1) caps size at 50 percent of the principal dwelling's gross floor area or 1,300 square feet, whichever is less, and limits it to two bedrooms. Clause (2) requires the apartment to be a complete living space with its own kitchen and bathroom, separated from the principal unit. Clause (3) requires a detached apartment to have an independent water source and wastewater system from the main house, or one approved by South Carolina DHEC.
Clause (4) restricts the apartment to a single-family, owner-occupied dwelling, with no more than one apartment per lot, ruling out use as separate investor rental property. Clause (5) requires the lot to be at least 50 percent larger than the district's normal minimum, unless the lot is five acres or more, and sets a two-acre minimum for accessory apartments in the RC district specifically. Clause (6) requires the apartment to meet all yard setbacks and sit at least 20 feet from the principal dwelling when detached, and clause (7) requires one additional off-street parking space on the lot.
Violations & Fines
An accessory apartment that exceeds the 1,300-square-foot or 50-percent size cap, adds a third bedroom, sits on a lot too small for the district, or is added to a rental (non-owner-occupied) property does not meet the conditions of Sec. 24-3.17 and is not entitled to operate as an approved conditional use; the planning and development department can require it be brought into compliance or discontinued.
Frequently Asked Questions
Can I rent out an accessory apartment in Aiken County?
How big can an accessory apartment be?
Do I need extra land for a detached accessory apartment?
Sources & Official References
Other rules in Aiken County
How Aiken County compares: Easiest Cities to Build an ADU·Compare Aiken County to another location·View the South Carolina accessory structures overview
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