WikEstWikEst
Home / ADU / South Carolina ADU rules

ADU rules in South Carolina

Representative cities: Charleston, Columbia.

Verify locally. South Carolina has a MANDATORY statewide modified code — the 2021 South Carolina Residential Code (IRC 2021 with SC modifications, effective Jan 1, 2023), adopted by the Building Codes Council and enforced by every city/county. Permit-exemption thresholds are set by state statute (S.C. Code § 40-59-265): sheds ≤200 sq ft, decks ≤200 sq ft AND ≤30 in, fences ≤7 ft, retaining walls ≤4 ft. Coastal counties add hurricane wind (130–160 mph) and floodplain rules. Always confirm with your local building department. ADU rules below are drawn from official sources — always confirm with the issuing building department before designing or building.

ADU permit rule

Permit requiredGenerally allowedcity authority
Fee basis
Valuation-based building + trade permits per the local fee schedule.
Typical timeline
Plan review; Charleston requires a full permit package (site plan, floor plans, often a floodplain elevation certificate).
Setback
Per local zoning; ADUs follow accessory-structure setback and lot-coverage rules.
Area threshold
South Carolina has no single statewide ADU mandate; local zoning controls size/number of ADUs.
Exempt if
None — an ADU always requires a building permit; local zoning governs.
Go / no-go
allowed
South Carolina has no statewide ADU law, but many cities (e.g., Charleston) allow accessory dwelling units in residential zones by local ordinance. Verify the specific district allowances (setbacks, parking, flood/storm requirements) with your city.
ADU official sources: South Carolina Code § 40-59-265 (Permit Exemptions) · SC Building Codes Council
🧮

Estimate build cost

Model this ADU's construction cost by type, size & finish.
📊

Model rental ROI

Turn the build cost into rent, payback & 20-year cash flow.

Frequently asked questions

Do I need a permit to build an ADU in South Carolina?

Per South Carolina rules, an ADU is "yes" for a permit and the authority is "city". South Carolina has no statewide ADU law, but many cities (e.g., Charleston) allow accessory dwelling units in residential zones by local ordinance. Verify the specific district allowances (setbacks, parking, flood/storm requirements) with your city. Always confirm with the issuing building department.

How big can an ADU be in South Carolina?

Area threshold: South Carolina has no single statewide ADU mandate; local zoning controls size/number of ADUs.

What are the ADU setbacks in South Carolina?

Setback: Per local zoning; ADUs follow accessory-structure setback and lot-coverage rules.

How much does an ADU permit cost in South Carolina?

Fee basis: Valuation-based building + trade permits per the local fee schedule.

State-wide sources: South Carolina Code § 40-59-265 — Exemptions from Building Permit Requirements · South Carolina Building Codes Council (2021 SC Code Adoptions) · City of Columbia — Planning & Development (Building Codes) · City of Greenville — Building & Permit Center

Related tools from our network

A focused set of free calculators and guides across related topics — no account required.

Practical tools

Money & tax