So-called “accessory dwelling units” (ADUs) are an old idea. In the 1890s they were called carriage houses and appeared along the alleys in back of the well-to-do homes, where they were often used as servants’ quarters.

But after being banished in the years since, Minneapolis is looking at whether to join other U.S. cities in welcoming ADUs back as a means to accomplish smart-growth goals and appeal to changing demographics.

This is especially true in their role as “granny flats,” in which homeowners in single-family-zoned areas are allowed to construct small additions with separate kitchens, entrances and bathrooms for aging relatives, or even to rent them out to provide extra income.

ADUs are popular in cities such as Vancouver, Seattle and Portland, Ore., where they are credited with transforming alleys into popular, walkable “lanes” and providing a means for families with limited finances to stay together in one spot even as they go through changes.

Backers say permitting ADUs will increase affordable-housing opportunities, give homeowners struggling with their mortgages a means to stay put and increase density in neighborhoods without having to build frequently controversial high-rise apartments.

Minneapolis, which currently allows ADUs only in the low-income Ventura Village neighborhood, is considering expanding their use as a permitted use as a way to provide housing alternatives for elderly residents who now must leave the city for senior housing in the suburbs, as well as to accommodate a growing population after decades of losing residents.

“It’s on our radar,” said Tom Streitz, the city’s director of housing policy and development.

“We are actively in conversation about ADUs and more broadly about keeping seniors in the city. We’re having a forum with developers next week to talk about new urban models for senior housing. We’re exploring different housing types to accommodate all the growth in Minneapolis.”

Probably the one Minneapolis resident with the most experience in dealing with ADUs is Jim Graham, an urban planner and housing designer who works with the Ventura Village neighborhood.

He studied carriage houses in the Twin Cities in the late 1990s while helping spearhead an effort to allow ADUs as a means of addressing the affordable housing crisis of the time.

The push resulted in a new zoning “overlay” district but it didn’t meet with much success — plans to build hundreds of new alleyway carriage houses never materialized over city concerns that unscrupulous landlords might try to wring more income from already overcrowded low-income properties.

“More than half the housing in Minneapolis now is occupied by one-person households,” Graham said, “so more than half would be comfortable in a carriage house. You can design them to be affordable and meet their particular needs but also use high-end architecture. It’s really a high-density housing option with a low impact.”

Homeowner interest in ADUs is indeed on the rise, added Minneapolis-based builder Mike Lucas of Gudhouse Co., which has constructed new single-family homes in the Linden Hills and Fulton neighborhoods.

“The expense of living in the city has gone up, and the question is how do you make something affordable for a family who may be taking care of mom and dad,” he said. “We want to keep all these people in the city — that’s what makes it diverse and interesting.”

Lucas said many city homes with detached garages could be outfitted with carriage house-style dwelling units, but he has had to turn away some potential customers because of zoning restrictions.

“Most of the interest I’ve encountered is from people in their 30s and 40s with aging parents who don’t want them driving all over town and who also see it as affordability issue. They’ve read about ADUs and it’s intriguing to them,” but because they’re not yet allowed, “the conversation is just starting.”


Don Jacobson is a freelance writer in St. Paul.