James City County, VA Accessory Structures: ADU Rules (2026)

Sec. 24-32 of the Code of the County of James City sets separate standards for attached and detached accessory apartments. Attached units are limited to one per single-family dwelling, must be designed so the building still reads as a single-family residence, must place any new entrance on the side or rear of the building, and cannot occupy more than 35 percent of the dwelling's floor area; because the apartment is treated as part of the main structure, it must meet every setback, yard and height rule that applies to main structures in its zoning district, and off-street parking must be provided under Sec.

24-54. Detached accessory apartments, which the ordinance says must be where approved, are limited to one per lot, may not occupy more than 50 percent of the floor area of the accessory structure, and cannot exceed 400 square feet regardless of the size of the accessory building housing it; a detached unit must also meet every setback, yard and height standard that applies to accessory structures, not main structures, in its district, and the structure's size and scale must be compatible with surrounding buildings. Both attached and detached apartments require off-street parking under Sec.

24-54, and a detached unit on a well or septic system needs health department approval before construction. These standards apply on top of, not instead of, the underlying district's use list, so a lot must also be zoned to allow an accessory apartment at all.