Charleston's Accessory Structures: The Rules That Matter

Every city handles accessory structures a little differently. In Charleston, South Carolina, there are 5 distinct rules that residents and property owners should be aware of. Some are stricter than what neighboring cities enforce, and others are more relaxed. Here is what you need to know.

ADU Rules

Charleston zoning caps accessory dwelling units at one per lot and 850 square feet of conditioned space, shrinking to 600 square feet if the ADU sits in an accessory building using the Sec. 54-506.f setback exception. The lot is capped at two dwelling units total, and the ADU adds one required off-street parking space under Sec. 54-214 of the Zoning Ordinance.

Key details: ADUs allowed per lot: One. Max total dwelling units: Two per lot. Max conditioned floor area: 850 sq ft (600 in accessory bldg). Required parking: One added off-street space. Governing section: Sec. 54-214(c)-(f).

Building or occupying an ADU without an approved site plan, DCR and certificate of occupancy violates Sec. 54-214 and, more broadly, the zoning permit requirement in Sec. 54-950. The city can withhold or revoke the certificate of occupancy under the recorded DCR's enforcement clause, Sec. 54-214(g)(8), and, under Sec. 54-950, treat an unpermitted ADU as a misdemeanor, issue a stop order, and pursue an injunction, with each day the violation continues counted as a separate offense.

ADU Rental Restrictions

Charleston's ADU covenant bars two things outright: subleasing the accessory dwelling unit and using either the ADU or the principal home as a short-term rental. Sec. 54-214(g)(2) and Sec. 54-214(g)(7) apply to every ADU approved on a lot, recorded permanently in the property's Declaration of Covenants and Restrictions.

Key details: Subleasing the ADU: Prohibited, Sec. 54-214(g)(2). Short-term rental use: Banned for both units, Sec. 54-214(g)(7). Recorded in: Declaration of Covenants and Restrictions. Enforcement: Revocation of certificate of occupancy. Governing section: Sec. 54-214(g)(2), (g)(7).

Subleasing an ADU or listing either unit as a short-term rental breaches Sec. 54-214(g)(2) and Sec. 54-214(g)(7) of the recorded covenant. Sec. 54-214(g)(8) authorizes the city to enforce the DCR by any legal or equitable means, including revoking the certificate of occupancy, and an unauthorized STR operation is separately a misdemeanor under Sec. 54-950 and Sec. 54-208(e)(2), each day continuing as its own offense.

This is not one of those rules that cities tend to ignore. Charleston actively enforces its adu rental restrictions requirements.

Tiny Homes

Charleston allows one accessory dwelling unit behind a single-family home in any base zoning district, capped at 850 square feet, or 600 square feet if it uses the setback-encroachment exception. The Zoning Administrator must approve a recorded covenant restricting rental and occupancy before a certificate of occupancy issues.

Key details: Governing section: Zoning Ordinance § 54-214. Max size (standard): 850 sq ft conditioned floor area. Max size (setback exception): 600 sq ft footprint, § 54-506.f. Units per lot: 1 ADU; 2 dwelling units total max. Parking: 1 off-street space required for the ADU.

Building or operating an ADU without the recorded Declaration of Covenants and Restrictions, or exceeding the 850-square-foot (600-square-foot for setback-exception units) size cap, is unlawful under Sec. 54-214 and enforceable through Sec. 54-950. The city can withhold or revoke the certificate of occupancy, and the DCR itself grants the City enforcement rights by any legal or equitable means, including revocation of occupancy approval, for breach of the ownership, rental income or short-term-rental restrictions.

ADU Owner Occupancy

Charleston requires either the main house or the accessory dwelling unit on a lot to be owner-occupied and serve as the owner's primary dwelling. Sec. 54-214(g)(1) blocks renting the ADU separately from the principal home whenever neither unit is owner-occupied, and the condition is locked into a recorded covenant.

Key details: Owner-occupancy test: Main house or ADU, not neither. If neither is owner-occupied: ADU cannot be rented separately. Recorded in: Declaration of Covenants and Restrictions. Governing section: Sec. 54-214(g)(1). Runs with: The land, binds future owners.

Renting the ADU separately from the principal home when neither unit is owner-occupied breaches the recorded DCR condition in Sec. 54-214(g)(1). Sec. 54-214(g)(8) gives the city the right to enforce the covenant by any legal or equitable means, including revocation of the certificate of occupancy, and an unpermitted use can also be pursued as a misdemeanor and enjoined under the general zoning penalty section, Sec. 54-950.

This is not one of those rules that cities tend to ignore. Charleston actively enforces its adu owner occupancy requirements.

Shed & Carport Rules

A backyard shed or accessory building in Charleston can encroach as close as one and a half feet from a side or rear lot line if its footprint stays at or under 100 square feet, or three feet if it runs up to 600 square feet, so long as it stays one story, sits behind the principal building, and meets the height and lot-occupancy limits in Table 3.1.

Key details: Small shed setback (100 sq ft or less): 1.5 feet from side/rear line. Larger shed setback (100-600 sq ft): 3 feet from side/rear line. Max footprint using exception: 600 square feet. Height limit, 1-story house: 1.5 stories, 11-foot eave. Height limit, 2+ story house: 2 stories, 24 feet total.

Building a shed or accessory structure without a permit, or one that exceeds the applicable footprint, height, or setback limits in Section 54-506, is a Chapter 54 zoning violation. Section 54-950 makes any violation of an ordinance adopted under the zoning chapter a misdemeanor, with each day of unlawful construction or maintenance treated as a separate offense, and authorizes the Zoning Administrator to withhold or revoke permits and issue stop-work orders until the structure is brought into compliance or removed.

The Bottom Line

Charleston is tougher than many cities when it comes to accessory structures. Out of the 5 rules covered here, 2 are rated strict. If you are a homeowner, renter, or business owner in Charleston, take the time to understand these requirements before they become a problem. Most violations come with fines, and some repeat violations can escalate.

These rules come from Charleston's publicly available municipal code. For complete penalty schedules, exemption details, and answers to common questions, see the individual ordinance pages throughout this guide.