ADU Pass
Charleston
Charleston County portion
Also in: No County
ADU Pass helps homeowners in Charleston, Charleston County, South Carolina navigate the permit paperwork for building an accessory dwelling unit. This area covers 5 ZIP codes.
Map
ADU details
ADU legality: unclear
South Carolina leaves ADU regulation to local municipalities under home-rule or Dillon-rule authority. Charleston permits ADUs subject to local conditions per its zoning ordinance.
Cost scenarios
| Scenario | Sq ft | Permit | Build | Total |
|---|---|---|---|---|
| minimum | 150 | $1,500 | $44,250 | $45,750 |
| 600 | 600 | $1,500 | $177,000 | $178,500 |
| midpoint | 525 | $1,500 | $154,875 | $156,375 |
| maximum | 900 | $1,500 | $265,500 | $267,000 |
Fee breakdown
Viability (permitted uses)
- Long-term rental: yes Long-term rental of ADU generally permitted; landlord-tenant law and any city rental-registration ordinance apply.
- Short-term rental: with-restrictions STR rules vary by city. Charleston regulates STRs separately from ADU permitting; check local STR ordinance and HOA covenants.
- Office rental: with-restrictions Detached office rental requires home occupation permit or rezoning.
- Home office: yes Home occupation permitted with restrictions on signage and customer traffic.
- Studio / workshop: yes Personal artist studio is a permitted accessory use.
- Agriculture: with-restrictions Limited urban agriculture permitted in residential zones; livestock varies by district.
- Relative support: yes Family-occupancy ADU explicitly permitted in single-family zones.
Utilities
- Water: Charleston Water Utility · 30d connect · $4,500
- Sewer: Charleston Sewer / Wastewater · 30d connect · $5,500
- Electric: Charleston Electric Utility · 21d connect · $1,800
- Gas: Charleston Gas Utility · 30d connect · $1,500
Property values & taxes
Construction timeline
Realistic total: best 7mo · typical 10mo · worst 16mo
Financing
Insurance impact
HOA prevalence & preemption
South Carolina has no statewide statute that voids HOA bans on ADUs. Common-interest communities in SC are governed primarily by the South Carolina Homeowners Association Act (Title 27, Chapter 30 of the SC Code) for HOAs and by the Horizontal Property Act (Title 27, Chapter 31) for condominiums. Restrictive covenants in declarations and bylaws — including those prohibiting accessory structures or secondary kitchens — remain enforceable per their terms.
Regulatory overlays (3)
- coastal-zone
Charleston has coastal-zone overlay; coastal development permit may be required for some sites. - flood-zone
Charleston has FEMA Special Flood Hazard Areas; elevation certificates and flood-resistant construction required for SFHA parcels. - historic-district
Charleston historic districts trigger Architectural Review Board / Historic Preservation Commission review for ADUs in historic boundaries.
Technical envelope (climate & building code)
Climate & energy code
Building code
Amendments:
- Amendment
- Amendment
Legal history (timeline)
Current ordinance: City of Charleston Municipal Code — Accessory Dwelling Units, adopted 2020-01-01, last amended 2024-04-01
- 2024-01-01 — City of Charleston ADU code refresh (city-ordinance)
Conforming local-code amendments aligning with current South Carolina accessory-dwelling framework.
Effect: Codified permissive ADU standards consistent with state law and local zoning.
Charleston County — county ADU rules and overlays
County ADU ordinance
Charleston County, SC (424,000 residents) administers the Charleston County Zoning and Land Development Regulations Ordinance (ZLDR) for unincorporated territory. Major cities include Charleston, North Charleston, Mount Pleasant, Folly Beach, Isle of Palms, Sullivan's Island, James Island, Hollywood, Ravenel, McClellanville. Coastal SFHA exposure is extensive across the county; ADUs in SFHA require elevation to or above BFE.
State-floor overlay: South Carolina has not enacted statewide ADU preemption.
County regulatory overlays
Charleston County administers flood-hazard, and (where mapped) coastal, wildland-fire, historic, and airport overlays that shape ADU project feasibility. The most consistent overlay across the county is FEMA NFIP floodplain regulation; other overlays apply to specific geographies inside the county.
- FEMA NFIP Special Flood Hazard Areas in Charleston County — A new ADU in a mapped SFHA must be elevated to or above the Base Flood Elevation; cost impact on the project is often material.
- Historic districts and individually-listed historic resources
County permitting (unincorporated parcels)
Charleston County issues building permits for parcels in unincorporated territory through its development services / planning department, with separate review tracks for zoning conformance, building-code compliance, on-site sewage where applicable, floodplain compliance, and addressing. Inside incorporated municipalities, city departments handle their own permits; the county's authority is geographically limited to unincorporated territory. An ADU permit application is typically processed as a residential building permit with a zoning verification step against the county's ordinance for the parcel's zoning district.
Federal (United States) — ADU-relevant rules and programs
Federal ADU law
The United States has no federal statute that directly regulates accessory dwelling unit entitlement or design. Land-use authority over ADUs resides with states and local governments under the traditional police power. Federal engagement is limited to financing (Fannie/Freddie/FHA/VA/USDA), flood insurance (FEMA/NFIP), and discretionary housing programs (HUD), which are recorded in sibling sections of this file.
Federal financing programs
Federal housing-finance agencies and GSEs set nationwide underwriting rules that govern whether an ADU can be financed, appraised, and counted toward mortgage qualifying income. The relevant actors are Fannie Mae, Freddie Mac, FHA (HUD), VA, and USDA Rural Development.
Federal tax credits
There is no ADU-specific federal tax credit. ADUs may incidentally qualify for existing federal energy-efficiency and clean-energy tax credits when the ADU construction includes qualifying measures.
Federal housing programs
HUD administers several discretionary programs that can fund ADU-related activity at the grantee's election, but none is an ADU-specific program.
ZIP Codes
- 29401
- 29403
- 29407
- 29412
- 29414
Post Office
- 1964 Ashley River Rd Ste B, 29407
- 557 E Bay St, 29403
- 579 Folly Rd, 29412
- 78 Sycamore Ave, 29407