Accessory Building, Structure, and Dwelling Unit Regulations

Terms

• An accessory building is a detached structure in the rear yard, such as a shed or garage.
• An attached ADU is located in the same building as the main dwelling. It can be created by altering a portion of the main dwelling or additions to the main dwelling. Examples include a basement conversion or home addition that contains an independent dwelling unit. 
• A detached ADU is located within an accessory building that is separate from the main dwelling. It can be created by retrofitting an existing detached structure or constructing a new detached accessory building on the same lot. Examples include an apartment over a detached garage or an individual dwelling within an accessory structure. Detached ADUs must be built on a foundation and meet the requirements for accessory buildings and structures found in Article 8, Division 8.1 of the Zoning Ordinance.

Applications

• Building ADU Permit Application
• Rental ADU License Application

Regulations for Accessory Buildings and Structures

Review the full regulations for accessory buildings and structures in Article 8, Division 8.1 of the Zoning Ordinance.

Accessory Building Height

• The maximum height at the minimum setback is 12 feet. Accessory buildings taller than 12 feet must be set back an additional 3 feet for each additional foot of height, up to 15 feet. Accessory buildings may exceed 15 feet in height, up to a maximum of 20 feet, with no additional setback required.
• Height is measured to the peak of the roof of an accessory building. In addition, accessory building heights are measured from the lowest point of the finished grade rather than at the front of the building.
• The height of any accessory building may not exceed the height of the main dwelling.

ADU and Accessory Building Size

• Accessory dwelling units may be up to 75% of the total floor area of the main dwelling unit on the lot, except that:
  • An attached ADU in a basement may occupy the entire basement.
  • A detached ADU may be up to 600 square feet if the main dwelling unit on the lot has a gross floor area of 800 square feet.
• For all other accessory buildings, the maximum footprint of any one accessory building is 750 square feet and cannot exceed the footprint of the main building. The maximum footprint of all accessory buildings on a single lot is 1,000 square feet.

Accessory Building Setbacks

• A minimum requirement of 3 feet of building setback is required from any lot line, with additional setbacks required for accessory buildings taller than 12 feet.

Regulations for Accessory Dwelling Units

All ADUs, existing and proposed, must be permitted through the city’s permitting processes. Permits and licenses can be applied for through the city’s permitting portal, MGO Connect.  

Review the full zoning regulations for ADUs in Section 25.6.3.6 of the Zoning Ordinance.

• Quantity: Only one ADU is permitted on a lot. ADUs must be accessory to a single-unit detached dwelling located on the same lot.
• Design: For attached ADUs, any external modifications to the single-unit detached dwelling must conform to applicable neighborhood design guidelines. If a separate entrance to the attached ADU is provided, it must be located on the side or rear of the principal dwelling unit.
• Owner occupancy: The property owner must occupy either the main building or the ADU for at least six months of the year. Both the ADU and the main dwelling on a lot must remain under common ownership.
• Parking: ADUs are not required to provide parking spaces.
• Rental: Only one rental license is permitted on a property.