Over the past several years, as middle-income housing becomes harder to find, many cities have started considering Additional Dwelling Units, or ADUs, on residential properties. Some come in the form of adapting an existing space (like a carriage house). Others are new construction on a property, adding density to a neighborhood. 

In 2021, Ann Arbor approved new regulations for ADUs, allowing new detached structures on a property. Architecture firm T+E+A+M co-founders Ellie Abrons and Adam Fure, collaborating with the firm’s other two co-founders Meredith Miller and Thom Moran, recently completed an ADU on their own .19-acre property in the city, with economy, efficiency, and privacy in mind.

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The Northwood ADU is 730 square feet, with one bedroom above the kitchen. The structure utilizes skylights and windows facing the side and adjacent forest, keeping the renters' privacy from the homeowners. The structure was built with frost-protected, insulated shallow foundation technology, common in Scandinavian countries, reducing the labor and expense of a lot of site work. Radiant floors, a heat pump and ductless mini-split, and an energy recovery ventilator maximize efficiency. The cost came in at $350 per square foot.

Fure says the ADU is easy to replicate. "It uses building systems that cut down on construction time by utilizing prefabrication, which is important in a labor market such as this. It’s also adaptable to many kinds of sites."

Abrons adds that homeowners planning on building their own ADUs should take these ideas into consideration. 

  • Keep costs down by considering efficient use of space and ways to make small spaces seem spacious with things like generous daylighting and high ceilings.
  • Consider sight lines and privacy between the main house and the ADU.
  • Think about how you might want to use the ADU in the future and design flexibility into the arrangement.
  • Research the local ordinances to find out what’s allowable, not only for the building constraints, but also things like whether you can use the ADU for short-term rentals or if there’s an owner-occupancy requirement.

Detroit is currently considering adding ADUs to its effort to modernize its zoning ordinance. We should see more movement on this later this year.

The Northwood ADU is one of the first built in Ann Arbor under the new zoning regulations. Considering the initial expense involved, we'll be watching to see if more residents start building their own.