ADU Rules in Fargo, North Dakota

Fargo is North Dakota's largest city and the economic hub of the Red River Valley. Situated on the west bank of the Red River directly opposite Moorhead, Minnesota, Fargo is in Cass County and is home to North Dakota State University (NDSU). The city has grown steadily and faces housing demand from students, university staff, and a diversifying economy.

No Statewide ADU Law — Local Zoning Controls

North Dakota has not passed any statewide legislation preempting or streamlining local ADU regulations. This means all rules governing Accessory Dwelling Units (ADUs) in Fargo are set entirely by the City of Fargo Zoning Ordinance. There is no state mandate requiring Fargo to allow ADUs or limiting the city's ability to regulate them.

ADU Types Potentially Allowed

Depending on the zoning district, Fargo may allow:

• Attached ADUs — an addition to the primary structure sharing a wall
• Detached ADUs — a separate accessory structure in the rear or side yard
• Garage conversions — converting an existing attached or detached garage into a living unit
• Interior/basement ADUs — a unit carved out of existing interior space

The specific types permitted vary by residential zone (such as SR-1, SR-2, MR zones, etc.). Review the Fargo Zoning Ordinance or consult the Planning and Development Department to confirm what is allowed in your zone.

Typical Development Standards

While specific standards must be confirmed with the City, ADUs in Fargo are generally subject to:

• Lot size minimums — a minimum lot area is typically required before an ADU is permitted
• Size limits — ADU floor area is commonly capped as a percentage of the primary dwelling or an absolute maximum (e.g., 800–1,000 sq ft)
• Setbacks — ADUs must meet rear and side yard setback requirements; detached ADUs in rear yards typically require at least a 5-foot setback from property lines
• Height limits — detached ADUs are typically limited to one story or a maximum height matching the accessory structure limits in the applicable zone
• Parking — additional off-street parking may be required for an ADU
• Owner-occupancy — some zones may require the property owner to occupy either the primary or accessory unit

Red River Flooding and Flood Zone Considerations

The Red River of the North has flooded Fargo severely — most notably in 2009 and 2011 when the city came within inches of catastrophic inundation. Fargo has since constructed substantial levee and diversion infrastructure, including the ongoing FM Area Diversion (Fargo-Moorhead Flood Diversion) project.

Properties near the Red River or its tributaries may fall within FEMA Special Flood Hazard Areas. ADU construction in these zones typically requires:

• Finished floors elevated above the Base Flood Elevation (BFE)
• Floodplain development permits in addition to standard building permits
• Compliance with floodplain management ordinance requirements

The FM Diversion project, once complete, may change FEMA flood zone designations for many Fargo properties. Always verify the current flood zone status of your parcel with the City Engineer's office or the FEMA Flood Map Service Center before designing or permitting an ADU.

Extreme Climate Requirements

North Dakota experiences some of the most extreme cold in the continental United States. Fargo regularly sees winter temperatures below −20°F. All construction — including ADUs — must comply with North Dakota building code requirements for:

• Frost depth: foundations must extend at least 42–60 inches below grade (verify current code requirement)
• Insulation: high R-values required for walls, roofs, and foundations
• Mechanical systems: heating systems must be adequately sized for extreme cold

Permit Process

To build an ADU in Fargo:

1. Verify your property's zoning district and confirm ADU allowance with Planning and Development
2. Obtain a zoning compliance review or conditional use permit if required
3. Submit building permit application with architectural drawings
4. Inspections required at foundation, framing, electrical, plumbing, and final stages

Contact Information

City of Fargo Planning and Development Department

• Website: fargond.gov/city-government/departments/planning-development
• Address: City Hall, 225 4th Street North, Fargo, ND 58102
• Phone: (701) 241-1474

Disclaimer: Zoning regulations change frequently. The information on this page is provided for general informational purposes only and may not reflect the most current rules. Always verify ADU requirements directly with the City of Fargo Planning and Development Department and consult a licensed architect or contractor before beginning any project.