Accessory Dwelling Units

Use the checklist below to determine if an ADU would be allowed on your property. City staff recommend answering “yes” to all relevant questions before applying for permits to construct an ADU.

1. Will my ADU include a kitchen with appliances, a full bathroom, and be completely separate from the main house?
2. If I want to construct an attached/interior ADU, will the ADU meet the following requirements:
   • The ADU can be no more than 40% of the gross floor area of the principal building.
   • Will the ADU be completely separate from the rest of the house (meaning a separate and lockable entrance)? Will the ADU share and have access to the living space in the main part of the house, and vice versa?
   • Can I meet building code requirements, particularly fire separation requirements?
3. If I want to construct a new detached ADU, will the ADU meet the following requirements:
   • The ADU must be 5 feet from side interior lot lines.
   • The ADU must be 15 feet from rear lot lines, unless the lot abuts an alley, then the ADU must be at least 5 feet from the lot line.
   • The ADU must have a permanent foundation on footings.
   • The ADU building must be no more than 15 feet tall, with a few exceptions.
   • The ADU must be at least 200 square feet.
   • A garage conversion to an ADU can't happen unless the required parking for the single-family home can be located in a structure or behind the front face of the house. An ADU does not require additional off-street parking.

1. Consult with staff on zoning and building code requirements. ADUs must meet the same requirements as any other apartment unit:
   • Fire separation for attached ADUs: Floor, ceiling, fire wall between side-by-side units (like any other apartment unit).
   • Egress and separate entrance.
   • Water and sewer connections – whether separate from main house or not, lines must be sized to adequately serve the demand from all features and units.
   • Tenant must be able to control their own utilities: hear/air, breakers (same as any apartment building), water shut-off, etc. The ADU does not necessarily need separate billing.
   • All ADUs should follow the new residential construction handout.
   • Converting existing garages: frost footings, slab/foundations for two stories, etc.
2. Apply for permits:
   • If demolition is part of the project, you will need a demolition permit.
   • All ADUs will require a building permit, and may require electrical, mechanical and/or plumbing permits.
   • An erosion and sediment control permit is required if the project will disturb 5,000 cubic feet.
   • Additions to the main house that add a second story or add 500 square feet or greater will require a construction management plan.
3. Once all permits are finalized, a certificate of occupancy will be issued for detached ADUs.
4. Apply for a rental license if the ADU will be rented out.

In January 2019, the city council decided to discuss accessory dwelling units (ADUs). An ADU is a self-contained residential unit that meets the requirements of the Minnesota State Building Code. ADUs are permanent installations that are legally part of a larger property that includes a standard single-family house. ADUs can sometimes be referred to as: carriage or coach houses, accessory apartments, backyard cottages, secondary dwelling units, granny flats, mother-in-law suites, second suites or garden apartments. These units may be located inside the principal building on a lot, or may be located in a detached accessory building on the same parcel.

ADUs have the potential to meet some of St. Louis Park’s housing and land use goals in the 2040 Comprehensive Plan update. Permitting ADUs in the city also helps fulfill the following city council strategic priority: St. Louis Park is committed to providing a broad range of housing and neighborhood-oriented development.

How many ADUs can I have on my property?

One per single-family residential lot.

Where in the city are ADUs allowed?

ADUs are permitted on single-family residential lots in the R1, R2 and R3 zoning districts.

Can I build an ADU on or over my garage?

Only if the ADU meets all zoning and building code requirements. Height limits may prevent full two-story detached buildings.

Can my ADU be a "tiny house?”

ADUs must be at a minimum 200 square feet, which is usually larger than a tiny house. Tiny houses often lack permanent foundations, which ADUs are required to have.

Can I build an ADU if I have a legally nonconforming lot?

If you can legally use the lot for a single-family residence, you can build an ADU, provided you meet all other ADU requirements for the size and location.

Do I need to provide additional surface parking on my property if I build an ADU?

No. Additional parking is not required, but is generally permitted.

Can an ADU be sold separately from the principal home?

No.

Does the property owner have to live on a lot with an ADU?

In order to legally establish an ADU, the owner must live on the property, either in the principal building or the ADU. If the owner sells the property, the new owner is not required to reside on the property.

May I rent out my ADU as a short-term rental, for example through AirB&B?

No. Short-term rental is only allowed for approved and licensed bed and breakfasts, hotels, motels or hostels.

How many people can live in an ADU?

Single-family lots may have one family and up to two roomers living on the property. They may live in the principal building or the ADU.

How much will it cost to build an ADU?

The cost to build an ADU varies widely and depends on many factors, including whether it's attached to the primary dwelling, the condition of any existing structures being utilized or if it will be all new construction. According to one source, a detached ADU in Minneapolis costs approximately $282,000 – $400,000 (Source: https://www.secondsuite.org/#legal, accessed August 27, 2020).

Will neighbors be notified if someone wants to build an ADU on their street?

No, unless the scale of the project requires a construction management plan.

• Family Housing Fund ADU guidebook for homeowners(PDF, 5MB)
• ADU Idea Book for Mid-Century Homes