Accessory Dwelling Unit (ADU) City Regulations

Number of ADUs allowed:

One accessory dwelling unit (ADU) is allowed per lot, if the lot is zoned for single family residential use and a primary dwelling exists on the property or is approved to be constructed in connection with the ADU. ~ State Standards

Types of ADUs allowed:

Construction of new detached and attached ADUs as well as conversions of garages, secondary structures, conversion of existing space within a primary dwelling is permitted. ~ State Standards

Lot size:

No minimum lot size is required to develop an ADU, other than any, required by the underlying zoning district. ~ State Standards

ADU size:

For detached ADUs, the total floor area of the unit shall not exceed 1,200 square feet. The increased floor area of an attached ADU shall not exceed 50 percent of the existing living area of the primary dwelling with a maximum increase of 1,200 square feet in floor area. No maximum floor area for conversions or existing space is established. The maximum floor area for a 'junior' ADU is 500 square feet. The minimum floor area for any ADU is 150 square feet. ~ State Standards


No setback shall be required for an existing garage that is converted to an accessory dwelling unit, and a setback of no more than five feet from the side and rear lot lines shall be required for an accessory dwelling unit that is constructed above a garage. Outside of these circumstances, setbacks for ADUs shall comply with the development standards of the underlying zone. ~ State Standards


Parking required for the establishment of an ADU shall not exceed one parking space per unit, plus one additional space per additional bedroom. These spaces may be provided as 'tandem' parking on an existing driveway. The ADU shall be exempt from all parking requirements if the property is located within 0.5 mile walking distance of a public transportation station. ~ State Standards

Fire Safety:

Accessory dwelling units shall not be required to provide fire sprinklers unless they are also required for the primary dwelling. ~ State Standards

Shape, materials and style:

Specific design styles and restrictions are not specified under State Standards. Passageways shall not be required in conjunction with the construction of an accessory dwelling unit. ~ State Standards


The maximum height of an ADU is not specified in the state standards. If ADU maximum height is not established locally, the height limitations of the underlying zone shall apply. ~ State Standards

Design review:

The municipality shall provide a ministerial review process which is not based on a discretionary approval for an ADU. The process shall take no less than 120 days. Valid applications submitted for ADUs, if not approved or denied within 120 days from submission, shall be considered approved. ~ State Standards

Number of Bedrooms:

No maximum number of bedrooms is established other than that implied by the maximum size of an ADU allowed. ~ State Standards


The ADU may be rented but shall not be intended for sale separate from the primary dwelling. ~ State Standards

Utility connections:

Connection and utility fees shall be reasonable, and shall not be disproportionately higher than those to develop primary dwellings, so as not to deter the development of ADUs. If a private sewage disposal system is used, such as a septic system, review and approval by a local health officer may be required. ~ State Standards

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