ADUs in Fairfax County previously were only permitted in single family detached homes where approved by the Board of Zoning Appeals. The occupant of the main house or ADU was required to be at least 55 years old or have a disability. Only single-family residences are permitted to have an ADU and only interior ADUs are permitted as-of-right. The homeowner must live in one of the units and there must be at least one parking space for the ADU. The ADU can have a maximum of two bedrooms.