Accessory Structures in Columbia, SC

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 4 specific rules on the books covering different aspects of accessory structures, and some of them might surprise you.

Shed & Carport Rules

Any accessory structure in Columbia, including a storage shed, must sit at least three feet from a side or rear property line, at least five feet from the main house unless it is open on all sides, and never inside the required front yard. Sec. 17-4.3(c) also requires the shed to serve, and stay subordinate to, the principal dwelling.

Key details: Side/rear setback: At least 3 feet from property line. Distance from house: 5 feet unless open on all sides. Front yard: Sheds not allowed in front yard. Ownership: Must be owned by same person as house. Timing: Cannot be built before principal structure.

An accessory structure built inside the three-foot side/rear setback, closer than five feet to the house, or inside the front yard is a Zoning Ordinance violation. The Zoning Administrator issues a notice of violation and, if uncorrected, may withhold pending permits, pursue civil or criminal penalties under Sec. 17-8.6, Remedies and Penalties, or require removal; each day the shed remains noncompliant counts as a separate violation.

ADU Owner Occupancy

Columbia requires an owner-occupancy commitment before an accessory dwelling unit can operate. Sec. 17-4.3(d)(1)b requires that either the principal house or the ADU itself be the permanent, full-time residence of the lot's owner, so an investor cannot buy a single-family property, build an ADU, and rent out both units to non-owner tenants.

Key details: Governing section: UDO § 17-4.3(d)(1)b, ADU owner-occupancy. Requirement: Owner must live in house or ADU. Both units rented: Not permitted; violates the standard. Related limit: ADU cannot be subdivided from principal lot. Enforcement: Misdemeanor, up to $500 fine or 30 days.

An accessory dwelling unit where neither the principal house nor the ADU is the owner's permanent, full-time residence is out of compliance with Sec. 17-4.3(d)(1)b. The Zoning Administrator can treat the property as an illegal two-unit rental, deny or revoke approval, and pursue remedies under Sec. 17-8.6; continued operation is a misdemeanor under Sec. 1-5, punishable by a fine up to $500.00 or 30 days' imprisonment, with each day a separate offense.

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

ADU Rules

Columbia allows one accessory dwelling unit (ADU) per single-family lot under Sec. 17-4.3(d)(1). The unit can be attached to the house or built as a detached structure like a garage apartment, but it is capped at the lesser of 1,000 square feet or 50 percent of the principal dwelling's floor area, limited to one kitchen, and does not count toward maximum density.

Key details: Governing section: UDO § 17-4.3(d)(1), Accessory Dwelling Unit. Units per lot: One ADU maximum per single-family lot. Size cap: Lesser of 1,000 sq ft or 50% of house. Detached separation: At least 10 feet from principal structure. Parking: One additional off-street space required.

Building a second accessory dwelling unit on a lot, exceeding the 1,000-square-foot/50-percent floor-area cap, installing a second kitchen, or running a home occupation inside an ADU violates Sec. 17-4.3(d)(1). The Zoning Administrator can deny or revoke the certificate of occupancy, issue a stop-work order, or pursue remedies under Sec. 17-8.6, and continued noncompliance is a misdemeanor under Sec. 1-5, fined up to $500.00 or 30 days' imprisonment per day of violation.

ADU Rental Restrictions

Columbia bans short-term rental of accessory dwelling units. Sec. 17-4.3(d)(1)i prohibits leasing or renting an ADU for any tenancy under 30 days, closing off Airbnb- or VRBO-style nightly rentals of a garage apartment or in-law suite even though the same code separately allows short-term rentals of a principal dwelling under its own Visitor Accommodation Uses standard.

Key details: Governing section: UDO § 17-4.3(d)(1)i, ADU rental restriction. Minimum tenancy: 30 consecutive days or longer. Short-term platforms: Airbnb/VRBO-style rentals of an ADU prohibited. Contrast: Principal house may qualify as separate STR use. Enforcement: Misdemeanor, up to $500 fine or 30 days.

Leasing or renting an accessory dwelling unit for a tenancy shorter than 30 days violates Sec. 17-4.3(d)(1)i, regardless of whether the listing runs through a short-term rental platform or a private booking. The Zoning Administrator can revoke the ADU's approval, issue a stop-work or cease-and-desist order, or pursue remedies under Sec. 17-8.6, and continued operation is a misdemeanor under Sec. 1-5, punishable by a fine up to $500.00 or 30 days' imprisonment, each day a separate offense.

This is one of the stricter rules in Columbia's municipal code. If you are unsure whether your situation complies, it is worth checking with the city before proceeding.

The Bottom Line

Columbia is tougher than many cities when it comes to accessory structures. Out of the 4 rules covered here, 2 are rated strict. If you are a homeowner, renter, or business owner in Columbia, take the time to understand these requirements before they become a problem. Most violations come with fines, and some repeat violations can escalate.

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.