Beaufort County, SC Accessory Structures: ADU Rules (2026)

Beaufort County adopted a multi-jurisdictional, form-based Community Development Code (CDC) that replaced its older Euclidean Zoning and Development Standards Ordinance. The CDC is published in the Beaufort County Municode library at library.municode.com/sc/beaufort_county/codes/community_development_code, and applies in all unincorporated areas of the county - the mainland 'Northern Beaufort' and 'Southern Beaufort' districts surrounding the Town of Bluffton, plus the unincorporated portions of the Lowcountry along U.S. 278 and SC 170. ADUs in the CDC are generally regulated as 'Carriage Houses,' a defined building type. Article 10 (Definitions) describes a Carriage House as a secondary accessory structure typically located at the rear of a lot that provides a small residential unit, home office, or other small-scale use, often above a garage or at ground level. Carriage houses are listed as a permitted building type in the form-based transect zones T3 (Edge / Hamlet Neighborhood / Neighborhood), T4 (Hamlet Center / Village Center / Neighborhood Center), and T5 (Town Center) zones, subject to the Building Type Standards in Division 5.1. Common carriage house standards across the CDC family of codes (mirrored in the City of Beaufort Code, the Town of Bluffton Unified Development Ordinance and the Daufuskie Island appendix) include: a maximum of two carriage houses per lot (one in T3-S sub-zones), the carriage house must be located to the rear of the principal structure (with side placement allowed as a secondary option), it must share architectural details (color, siding, roof pitch, window detailing, roofing materials, height and foundation) with the principal dwelling, one off-street parking space per carriage house is required and shall be clearly defined, the lot must be served with public water and sewer, and a maximum of two bedrooms is permitted. Daufuskie Island's CDC appendix (Section B.3.20, Consolidated Land Use Table) caps the auxiliary dwelling unit at 800 heated square feet whether attached to the principal dwelling or contained in a separate accessory structure on the same lot, and lists ADUs as permitted in zones D2R, D2R-CP, D2R-GH, D3GN, D4MU, D5VC and D5GC. Beaufort County's general accessory-structure rules (independent of carriage houses) require a zoning permit from the Beaufort County Planning & Zoning Department before placing any accessory structure; structures 200 square feet or larger also require a building permit through Beaufort County Building Codes; pre-built/manufactured sheds, garages and similar structures are not exempt from the building-permit threshold; and shipping containers, travel trailers, and recreational vehicles are prohibited as primary or accessory structures in all unincorporated zoning districts. An accessory structure cannot be placed on a parcel that has no principal structure or principal use. Properties inside the Town of Hilton Head Island are governed by the Hilton Head Land Management Ordinance (LMO), Title 16 of the Town Code (not the County CDC); properties inside the Town of Bluffton are governed by the Bluffton Unified Development Ordinance; and properties inside the City of Beaufort or Town of Port Royal follow their separate codes. South Carolina has not enacted a statewide ADU preemption law (H.3469 the 'ADU Affordable Housing Incentive Act' remains pending in the General Assembly), so the Beaufort County CDC and the municipalities' codes control in their respective jurisdictions.