Everything You Need to Know About Building an ADU in Minnesota

What is an ADU?

An Accessory Dwelling Unit (ADU) is a secondary residential structure on a single-family lot. It can be a backyard cottage, above-garage apartment, in-law suite, or even a converted basement or attic. ADUs are fully independent living spaces, complete with kitchens, bathrooms, and private entrances.

Who are ADUs for?

ADUs are for grandparents, adult children, families, rental income… or just more space for your home office or studio.

Why are ADUs important?

A Second Suite/ADU allows city residents to expand without increasing the mass of the primary residence.

ADUs also allow for multi-generational living while maintaining independence and privacy from the primary home. Families can share resources, provide care-giving, and enjoy spending time together. ADUs are a cost-effective alternative to an apartment or even an assisted living facility.

Are ADUs legal in Minneapolis and St. Paul?

Yes. Both Minneapolis and St. Paul allow ADUs on most residential lots, subject to zoning, size, and setback requirements. Our team at Second Suite is well-versed in Twin Cities ADU regulations and will guide you through the permitting process to ensure your project is 100% compliant.

What cities in the metro allow ADUs?

Chris Strom, Principal Architect and Founder of Second Suite, has been a leading figure in advancing Accessory Dwelling Unit (ADU) policy throughout Minnesota. Minneapolis became the first city in the state to legalize ADUs in 2014, and Chris played a key role by assisting the City of Minneapolis with both the initial ordinance and subsequent code updates.

Following Minneapolis, St. Paul legalized ADUs in 2018, and St. Louis Park did so in 2020. Chris also assisted the City of Edina in creating their ADU ordinance, which legalized ADUs in 2024.

Today, numerous Minnesota cities permit ADUs, including Bloomington, Burnsville, Columbia Heights, Credit River, Crystal, Duluth, Eagan, Fridley, Golden Valley, Long Lake, New Brighton, Northfield, Orono, Richfield, Rochester, Wayzata, and White Bear Lake. Each community has its own set of detailed regulations, and the team at Second Suite is well-versed in navigating these local requirements.

In the summer of 2025, Chris consulted with the City of Brooklyn Park as they explored potential future ADU legalization; however, ADUs are not yet permitted in Brooklyn Park.

If your city has not adopted ADU regulations, you can help advocate for future legalization by contacting your local City Planner or Community Development staff.

How much does it cost to build an ADU in the Twin Cities?

Costs vary depending on the size, design, and type of ADU. Most ADU projects in Minneapolis and St. Paul range from $400,000 to $600,000.

How long does it take to design and build an ADU?

On average, the full process takes 12 months, including design, permitting, and construction. We manage everything in-house to streamline the timeline as much as possible.

What types of ADUs can you build?

We tailor each project to your property layout, goals, and city code. We specialize in a wide range of custom ADU types, including:

• Detached backyard cottages

• Above-garage apartments

• Basement or attic conversions

• Attached additions or in-law suites

What are the design options?

Accessory dwelling units (ADUs) are custom-designed for your location by Christopher Strom Architects. Homeowners may decide to “build-to-blend” with the character of their existing home, or take things in another direction and add a pleasing modern counterpoint to their yard. To find inspiration for your own ADU, view our completed projects, including Sunflower, Compact Living, Alley Cat, and GreenHouse. 

Can I rent out my ADU?

Yes. In both Minneapolis and St. Paul, ADUs can be rented as long-term housing units. Short-term rentals like Airbnb are restricted in some areas, so it is best to discuss with your local jurisdiction.

Will an ADU increase my property value?

Yes. A well-designed ADU can enhance your home’s resale value, provide rental income, or create flexible space for multigenerational living—making your home more versatile and valuable.

Do I need a permit to build an ADU?

Yes. All ADUs in the Twin Cities require building permits and zoning approvals. We handle this process for you—from initial feasibility to final approval—so you don’t have to navigate it alone.

How do I know if my property is eligible for an ADU?

We offer an ADU feasibility study to determine what is possible for your lot. We’ll review your zoning, lot size, setbacks, and utility access, then provide recommendations based on local regulations and your goals.

Can I bring/use my own builder?

Absolutely! We are happy to work with your preferred builder. We are also pleased to act as a “matchmaker” and suggest possible builders who align with your priorities.

Why work with Second Suite?

Second Suite is an offering from Christopher Strom Architects, a Twin Cities residential architecture firm. With a deep background and experience in ADU design, we have helped many clients realize their dream of more space in their own backyard.

Still have questions?

We’re here to help. Contact us to schedule a consultation or request an ADU feasibility study.