York County, VA Accessory Structures: ADU Rules (2026)

Sec. 24.1-407 governs accessory apartments paired with a single-family detached dwelling. Only one accessory apartment is permitted per lot, whether attached to the house or in a detached accessory structure. By right, the unit cannot exceed 1,000 square feet or 35% of the principal structure's floor area, whichever is less, and this by-right allowance applies only in the RC, RR, R33, R20, and R13 zoning districts. With a special use permit from the Board of Supervisors, the maximum size can grow to 49% of the principal structure's floor area, but it can never exceed 1,000 square feet regardless of the permit.

A detached accessory apartment structure's footprint cannot exceed 75% of the principal structure's footprint. The apartment can have no more than one bedroom, and habitable space is calculated under the Building Code's definition. No new entrance for the apartment may be added to the front façade facing the street, so the property keeps the appearance of a single-family home, and the applicant must submit sketches showing compliance. Off-street parking must be provided in a way compatible with the neighborhood's character, and the Health Department must certify that on-site water supply and sewage treatment can serve the total bedroom count across both the principal home and the accessory apartment before approval.