Accessory Structures in Columbia, SC: What Residents Actually Need to Know

If you live in Columbia or are thinking about moving there, accessory structures are one of those things you probably won't think about until they affect you directly. Columbia has 8 specific rules on the books covering different aspects of accessory structures, and some of them might surprise you.

Carport Rules

Columbia regulates carports as accessory structures under Sec. 17-4.3 of the Unified Development Ordinance. Detached carports must meet accessory-structure setbacks and zoning standards, with a building permit generally required if the structure exceeds 200 sq ft.

Key details: Code: UDO Sec. 17-4.3. Classification: Accessory; not fully enclosed. Permit Threshold: >200 sq ft (detached). Side/Rear Setback: 3 ft min (typical). Front Yard: Not allowed in required yard.

Building a carport without a required permit, encroaching into a required yard, or exceeding lot coverage is a UDO/zoning violation enforced by Planning & Development Services. Remedies include stop-work orders, removal orders, and code enforcement penalties; structures in historic overlays without a Certificate of Design Approval face additional remedies.

ADU Owner Occupancy

Columbia's Unified Development Ordinance Sec. 17-4.3(c) requires that either the principal dwelling or the accessory dwelling unit be the permanent, full-time residence of the owner of the lot. This owner-occupancy condition applies to every ADU citywide, regardless of whether it is rented long-term or owner-used. Only one ADU is allowed per lot, and the ADU and principal dwelling remain a single legal parcel that cannot be sold separately.

Key details: Owner-Occupancy: Required (UDO Sec. 17-4.3(c)). Applies To: Principal OR ADU as owner residence. Limit Per Lot: One ADU. Separate Sale: Not allowed (one legal parcel). State Law: SC Code §27-40 (landlord/tenant).

Renting both the principal dwelling and the ADU while not occupying either as the owner is a violation of Sec. 17-4.3(c) and triggers code-enforcement action under Chapter 17. Misrepresenting owner-occupancy on permit or STR applications is grounds for permit revocation and civil penalties under Columbia Code Chapter 17. Confirm current penalty amounts with Columbia Planning and Development.

Compared to other cities, Columbia takes a harder line on adu owner occupancy. The enforcement and penalty structure reflects that.

ADU Impact Fees

Columbia does not impose general municipal impact fees on residential ADUs. New connections to Columbia Water trigger water and sewer tap fees and capacity charges. Any local impact fee in South Carolina must comply with the strict procedural rules of the SC Development Impact Fee Act (SC Code §6-1-910 to §6-1-2010), which requires a capital improvements plan, public hearings, and a rational nexus between the fee and the service. Standard zoning and building permit fees from Columbia's fee schedule apply.

Key details: General Impact Fees: None on ADUs in Columbia. State Authority: SC Code §6-1-910 to §6-1-2010. Procedural Rules: CIP, hearings, rational nexus. Utility Tap Fees: Columbia Water charges new connections. Stormwater Fee: Per Columbia SMP.

Failure to pay required water/sewer tap fees or building permit fees blocks permit issuance and final inspection. Unpaid Columbia Water connection charges may become a lien on the property. Disputes over impact fees imposed under §6-1-2010 follow the statutory appeal process in the SC Development Impact Fee Act. Confirm current fee amounts with Columbia Planning and Development and Columbia Water.

ADU Permits

Columbia permits accessory dwelling units (ADUs) under the Unified Development Ordinance (UDO), Chapter 17 Sec. 17-4.3(c) of the Columbia Code of Ordinances. An ADU requires a zoning permit and a building permit, with construction subject to the 2021 International Residential Code as adopted by the South Carolina Building Codes Council. ADUs may be attached, internal (basement or upstairs), or detached, and floor area is capped at the lesser of 1,000 square feet or 50% of the principal dwelling's floor area.

Key details: Code: Columbia UDO Sec. 17-4.3(c). Size Cap: Lesser of 1,000 sf or 50% of principal. Setbacks: 3 ft side/rear; 5 ft from main building. Building Code: 2021 IRC / IBC (SC adopted). Limit Per Lot: One ADU.

Building an ADU without a zoning permit or building permit triggers a stop-work order and code-enforcement action under Chapter 17 of the Columbia Code of Ordinances. Unpermitted work in a designated historic district may require Design/Development Review Commission after-the-fact review and possible restoration. Confirm current penalty amounts with Columbia Planning and Development.

ADU Rental Restrictions

Columbia allows long-term rental of an ADU subject to the UDO Sec. 17-4.3(c) owner-occupancy condition: either the principal dwelling or the ADU must be the owner's permanent residence. Short-term rental (30 days or less) of an ADU is regulated by Columbia Ord. 2023-037, which requires a Short-Term Rental Permit, a city Business License, and a local representative within 45 miles of city limits. Long-term tenancy is otherwise governed by the SC Residential Landlord and Tenant Act, SC Code §27-40, and University of South Carolina student rentals are common in nearby neighborhoods.

Key details: Long-Term Rental: Allowed with owner-occupancy of one unit. STR Ordinance: Ord. 2023-037 (effective May 4, 2023). STR Permit Fees: $100 owner-occ / $250 non-owner-occ. Local Rep: Within 45 miles of city limits. State Law: SC Code §27-40 long-term tenancy.

Operating a short-term rental without a city STR Permit and Business License is a Chapter 17 violation; civil penalties escalate per occurrence and the city may suspend or revoke the permit and business license. Violating the UDO Sec. 17-4.3(c) owner-occupancy condition triggers separate code enforcement. Failure to remit state and local accommodations taxes is referred to the SC Department of Revenue. Confirm current penalties with Columbia Planning and Development.

ADU Rules

Columbia's UDO addresses accessory dwelling units. ADUs may be permitted in certain residential zones subject to size and design standards.

Key details: Zoning: Certain districts per UDO. Permit: Required. Setbacks: Must comply. Review: Planning & Development.

Unpermitted ADUs face code violations. May be required to obtain permits or remove.

Shed Rules

Columbia allows sheds subject to size and setback requirements. Small sheds may not require building permits.

Key details: Small Shed: Under 120 sq ft may be exempt. Location: Rear/side yard. Setbacks: Must comply. Use: Storage only.

Code enforcement for setback violations. Unpermitted structures may be ordered removed.

Garage Conversions

Columbia requires building permits for garage conversions. The space must meet building code standards for habitable rooms.

Key details: Permit: Required. Parking: Must maintain minimum. Building Code: Habitable standards. Egress: Windows required.

Unpermitted conversions face code violations. May need to restore or obtain permits.

The Bottom Line

Columbia's accessory structures rules are a mixed bag. Some areas are strict, others are relaxed, and the details matter. The best approach is to check the specific rule that applies to your situation rather than assuming Columbia is broadly strict or permissive.

Keep in mind that Columbia can amend these rules at any council meeting. For the most current version of any rule mentioned here, check the specific ordinance page, where we track updates as they happen.