Washington County to Allow Accessory Dwelling Units (ADUs) in Rural Areas

In a move that aligns with state legislation and enhances rural housing options, Washington County will allow Accessory Dwelling Units (ADUs) within rural residential districts outside an urban growth boundary.

The Board of County Commissioners voted unanimously to adopt Ordinance No. 912A on April 28.

“By allowing ADUs in rural areas of the County, we’re giving our rural communities some housing flexibility they haven’t had before,” said Jerry Willey, Commissioner for District 4, which includes rural areas of Washington County. “ADUs will better provide multi-generational families the opportunity to live together while maintaining the farming heritage that make these communities so special. It’s a balanced approach that preserves the rural lands we love, while planning for the future.”

Ordinance Overview:

• Allows one Rural ADU per lot, or conversion of a historic home to a Rural Historic ADU, in rural residential districts (AF-5, AF-10, and RR-5) under certain conditions
• Caps the size of a new Rural ADU at 900 square feet.
• Applies to most lots two acres or more in rural residential districts (AF-5, AF-10, and RR-5) outside an urban growth boundary or urban reserve and not in a groundwater-restricted area unless the rural ADU is served by an external water provider
• Requires Rural ADUs and Rural Historic ADUs to have sufficient fire protection
• Prohibits vacation occupancy, ensuring that Rural ADUs and Rural Historic ADUs serve local housing needs rather than short-term market demands

“For years we have received requests for ADUs to be allowed rural areas. We studied the topic, listened to public feedback, and now have a way to provide more housing options for our rural community members,” said Washington County Senior Planner, Todd Borkowitz.

The ordinance will take effect May 28, 2026.