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

Chapter 23, Article 6, Division 28 of the Spotsylvania County Code sets up the Mixed Use (MU) district, a five-tier zoning classification (MU-1 through MU-5) created to mix housing, retail, office and civic uses in a walkable pattern. Within that district, Sec. 23-6.28.4(a) defines eight building types, including the Accessory Apartment, described as a small dwelling located on the same lot as a detached house, attached house, or townhouse, and the code specifically notes it may be located above a garage. The building-type table in the same section shows which sub-districts allow an accessory apartment as a matter of right.

The dimensional standards in Sec. 23-6.28.4(l) cap an accessory apartment lot at two dwelling units maximum and require a minimum building footprint of 200 square feet. Setbacks are tighter than for the principal house types: a 50-foot minimum from the primary street, 10 feet from a side street, 5 feet from a common side lot line, and 3 feet from a common rear lot line (4 feet, or 18 feet where there is no alley, along a rear alley). The standards also require a minimum 10-foot separation between the accessory apartment and any other building on the lot, though buildings connected only by a single breezeway still count as separate structures for that purpose. Vehicular access must come from an alley, or from the street only where no alley exists.

Because this building type exists solely inside the MU classification, a lot zoned Agricultural, Rural Residential, or one of the county's other conventional residential districts has no accessory-apartment allowance under this provision; a property owner outside the MU district must pursue a rezoning or a different accessory-structure pathway.