Richland County, SC Accessory Structures: ADU Rules (2026)
ADU rules in Richland County, SC, also called accessory dwelling unit regulations or granny flat ordinances, cover setbacks, owner-occupancy, parking, and permit requirements.
Key Facts
- Allowed
- One ADU per single-family lot
- Max size
- 500 sq ft or 1/4 heated area
- Manufactured home ADU
- Not permitted
- Districts
- RU, RR, RS-E/LD/MD/HD, M-1
- Authority
- Richland County LDC Sec. 26-151
Summary
Yes. Unincorporated Richland County allows one accessory dwelling per single-family lot in most residential and rural districts. The unit cannot exceed 500 square feet or one-fourth of the principal home's heated floor area, whichever is greater. A manufactured home may not serve as an accessory dwelling.
Accessory dwellings shall be located only on lots containing one single-family detached structure. Only one accessory dwelling shall be permitted per single-family dwelling. A manufactured home may not be used as an accessory dwelling. The gross floor area of the accessory dwelling shall not exceed five hundred (500) square feet or contain more than one-fourth of the heated floor area of the principal single-family dwelling, whichever is greater.
Official source re-checked September 7, 2026: no newer edition of the code had been published (publisher’s edition: 2026 S-24: This supplement is current through Ordinance No. 033-25HR).
Full Breakdown
Under the Land Development Code, accessory dwellings are a permitted use with special requirements in the RU, RR, RS-E, RS-LD, RS-MD, RS-HD and M-1 districts. They may be placed only on a lot containing one single-family detached home, and just one is allowed per single-family dwelling. If the unit shares the principal structure, the home cannot be altered to appear from the road as multi-family housing. Inside a city (Columbia, Forest Acres, Blythewood), that city's zoning applies instead of the county code.
Violations & Fines
Building or occupying an ADU that violates the LDC is a zoning violation enforced by the Planning Department under Article XII code-compliance provisions, including stop-work and citation.
Frequently Asked Questions
Can I put two accessory dwellings on my lot?
Can I use a mobile home as my ADU?
Sources & Official References
Other rules in Richland County
How Richland County compares: Easiest Cities to Build an ADU·Compare Richland County to another location·View the South Carolina accessory structures overview
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