ADU Rules in Charleston, SC (2026)
ADU rules, permit requirements, size limits, and fees for Charleston, SC. Source-cited from official municipal code.
Yes, ADUs are allowed in Charleston, SC.
Charleston, SC permits accessory dwelling units (ADUs) on residential properties. ADUs — also called granny flats, in-law units, backyard cottages, or secondary suites — are secondary housing units on a single-family or multifamily lot. State and local law governs the approval process. In Charleston, the local building department handles ADU permit applications. Below you will find the current size limits, setbacks, fees, and timeline for building an ADU in Charleston.
ADU Size Limits
ADU Size Limits in Charleston: Detached ADU: up to 850 sq ft (max height: varies — see official source). Attached ADU: size varies by zoning — see official source. Charleston Zoning Ordinance Chapter 54. Detached ADUs limited to 1,000 sqft. In the historic downtown peninsula, the detached ADU form follows the traditional Charleston Single house typology — side-facing piazzas and rear dependency structures are historically appropriate accessory unit forms. JADU is a California-specific designation not applicable in South Carolina.
| Type | Max Size | Max Height |
|---|---|---|
| Detached ADU | 850 sq ft · Verified June 7, 2026 · Source | See official source |
| Attached ADU | See official source | See official source |
Permit Fees
ADU Permit Fees in Charleston: Plan check fee: Varies. Building permit fee: Varies. Impact fees: None. School fees: None or N/A. Total estimated permit cost: Varies.
| Fee Type | Amount |
|---|---|
| Plan Check | $250–$900 |
| Building Permit | $500–$2,500 based on construction value |
| Impact Fees | None |
| School Fees | None |
| Total Estimate | See official source |
Permit Timeline
Charleston ADU Permit Timeline: Permit timeline has not been confirmed — contact the department for current processing times. Apply through the local building department online permit portal. Contact them through their official website for current contact information.
Setback Requirements
ADU Setback Requirements in Charleston: Front setback: follows zone standard. Side setback: no minimum. Rear setback: no minimum.
Parking Requirements
Parking Requirements: 1 off-street parking space required per ADU
Restrictions & Requirements
- Maximum one ADU per single-family residential lot
- ADU must be on same lot as primary dwelling
- Old and Historic District properties require BAR Certificate of Appropriateness
- Historic exterior materials must be contextually compatible — no modern siding, vinyl windows, or inappropriate materials in historic districts
- Flood zone properties require elevated construction above Base Flood Elevation
- ADU rental use regulated by separate Charleston STR ordinance
- Charleston peninsula's high ground coverage rates may limit ADU feasibility on smaller lots
How Many ADUs Are Allowed?
Number of ADUs Allowed in Charleston: Single-family lots: not confirmed — see official source. Multifamily properties: not confirmed — see official source.
- Single-Family Lots
- 1
- Multifamily Properties
- Additional units within base zone density limits
Statewide Preemption
ADU Preemption
We could not confirm a statewide ADU preemption statute for South Carolina.
View South Carolina preemption detailsFrequently Asked Questions
Can I build an ADU in Charleston?
Yes. Charleston, SC allows accessory dwelling units. On a single-family lot you can build 1.
How big can an ADU be in Charleston?
The maximum size for a detached ADU in Charleston is 850 square feet.
How long does it take to get an ADU permit in Charleston?
The typical ADU permit timeline in Charleston is Charleston Department of Planning, Preservation and Sustainability processes permits. Standard ADU: 4-8 weeks. Historic district ADU: additional 6-12 weeks for BAR Certificate of Appropriateness review. BAR meets monthly — applicants must submit in advance of monthly meeting. Charleston's historic review is detailed and thorough — pre-application consultation is essential.. Total estimated permit fees are $1,000–$5,000 total (add $600–$2,000 for BAR historic review).
Do I need extra parking for an ADU in Charleston?
Charleston parking rules for ADUs: 1 off-street parking space required per ADU
Do I have to live on-site to have an ADU in Charleston?
Owner-occupancy requirement in Charleston: Either the principal dwelling unit or the ADU must be owner-occupied and serve as the primary dwelling unit for the owner of the lot
Source: Charleston Zoning Ordinance Chapter 54; Board of Architectural Review Guidelines. Last verified April 6, 2026. View source