York County, SC Accessory Structures: ADU Rules (2026)
ADU rules in York County, SC, also called accessory dwelling unit regulations or granny flat ordinances, cover setbacks, owner-occupancy, parking, and permit requirements.
Key Facts
- Districts allowed
- AGC, RUD, RSF-40/30, RMX-20/10/6, MU, etc.
- Limit
- 1 ADU per lot
- Size
- 400 sq ft min, 50% of house max
- Height (separate bldg)
- Up to 125% of house height
- Parking
- 1 space/bedroom, extra to house
- Design
- Must match house roof, siding, color
Summary
York County allows one accessory dwelling unit per lot in the AGC, AGC-I, RUD, RUD-I, RSF-40, RSF-30, RMX-20, RMX-10, RMX-6 and MU districts under § 155.630, sized between 400 square feet and 50% of the house's floor area, with one parking space per bedroom on top of the house's own required parking.
§ 155.630 APPLICABILITY. (B) Accessory dwelling units are allowed as an accessory use to a single-family detached dwelling in the AGC, AGC-I, RUD, RUD-I, RSF-40, RSF-30, RMX-20, RMX-10, RMX-6, and MU zoning districts. § 155.631 ESTABLISHMENT AND USE. (A) Limit on number of accessory dwelling units. Only one accessory dwelling unit may be constructed or established per lot. (B) Configuration. An accessory dwelling unit may be in the same building or a separate building from the principal dwelling unit and may be located within or above the same structure as the garage. § 155.632 DIMENSIONS. (A) Minimum size. The habitable floor area of an accessory dwelling unit shall be at least 400 square feet. (B) Maximum size. The habitable floor area of an accessory dwelling unit shall not exceed 50% of the habitable floor area of the principal dwelling unit on the lot.
Official source re-checked September 7, 2026: no newer edition of the code had been published (publisher’s edition: 2026 S-49: Supplement contains: Local legislation current through Ord. 3925, passed 6-16-25).
Full Breakdown
630 limits accessory dwelling units to a listed set of districts: AGC, AGC-I, RUD, RUD-I, RSF-40, RSF-30, RMX-20, RMX-10, RMX-6, and MU, allowed only as an accessory use to a single-family detached dwelling. 631(A) caps a lot to one accessory dwelling unit, and (B) lets it be built in the same building as the house, in a separate building, or within or above a detached garage. 632 sets the size band: at least 400 square feet of habitable floor area, but no more than 50% of the principal dwelling's habitable floor area, and if the unit sits in a separate building, that building can't exceed 125% of the principal dwelling's height.
633 requires the unit to be a complete independent living facility with permanent provisions for living, sleeping, eating, cooking and sanitation under the building code, at least one off-street parking space per bedroom in addition to the house's own required parking, and exterior materials, roof pitch and color that match the principal dwelling. 631 also sets an owner-occupancy condition and bars certain dwelling types from serving as the unit, both covered in more detail elsewhere in the code.
Violations & Fines
Building or operating an accessory dwelling unit outside the listed districts, beyond one per lot, or without meeting the § 155.632 size band or § 155.633 parking and design standards is a misdemeanor under § 155.9999, punishable by a fine of up to $500 per day per violation, and the Planning and Development Services Director can order the unit brought into compliance or removed.
Frequently Asked Questions
Where can I build an ADU in unincorporated York County?
How big can an accessory dwelling unit be?
Can I put a manufactured home or RV in as my ADU?
How much parking does an ADU need?
Sources & Official References
Other rules in York County
How York County compares: Easiest Cities to Build an ADU·Compare York County to another location·View the South Carolina accessory structures overview
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