Mount Pleasant, SC Accessory Structures: ADU Owner Occupancy (2026)
Key Facts
- Owner-occupancy
- Principal home or ADU must be primary residence
- Occupancy cap
- Max 3 persons in the ADU
- Ownership rule
- No horizontal ownership regime conversion
- Mechanism
- Recorded covenant running with the property
- Citation
- § 156.445(E)(1)-(3)
Summary
Mount Pleasant requires a recorded covenant before an accessory dwelling unit can be used. Section 156.445(E) mandates that either the principal structure or the ADU be owner-occupied as the owner's primary residence, caps ADU occupancy at three persons, and bars converting the property into a horizontal ownership regime.
(E) Recorded covenant required. The following conditions shall be memorialized in a recorded covenant to run with the property: (1) Either the principal structure or the accessory dwelling unit must be owner-occupied and serve as the owner's primary residence; (2) Occupancy of the accessory dwelling unit shall be limited to no more than three persons; and (3) Under no circumstances shall the property be converted to a horizontal ownership regime.
Full Breakdown
445(E) of Mount Pleasant's zoning code, "Recorded covenant required," attaches three permanent conditions to every accessory dwelling unit that must be memorialized in a covenant recorded against the property. First, either the principal structure or the ADU itself must be owner-occupied and serve as the owner's primary residence, so a lot with an ADU cannot be fully rented out to non-owner tenants in both the main house and the ADU at once. Second, occupancy of the ADU is capped at no more than three persons.
Third, the property can never be converted to a horizontal ownership regime, which forecloses selling the ADU and the principal structure as separately owned units, such as a condominium-style split. 445(F). 445(D), all adopted together by the ordinance passed January 14, 2025, and administered by the Department of Planning, Land Use, and Neighborhoods.
Violations & Fines
Leasing out both the principal dwelling and the ADU to non-owner tenants, exceeding the three-person ADU occupancy cap, or attempting to convert the property to a horizontal ownership regime breaches the recorded covenant under § 156.445(E) and is a zoning violation the Planning, Land Use and Neighborhoods Department can enforce. Since Chapter 156 sets no separate fine for this subsection, the Town's general penalty clause at § 10.99 applies: up to a $500 fine, up to 30 days imprisonment, or both, with each day of continuing violation charged separately.
Frequently Asked Questions
Can I rent out both my house and my ADU in Mount Pleasant?
How many people can live in a Mount Pleasant ADU?
Can I sell my ADU separately from the main house?
Sources & Official References
Other rules in Mount Pleasant
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ADU Owner Occupancy in Nearby Cities
How other cities in Charleston County handle adu owner occupancy.