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Accessory Dwelling Units (ADUs) in Madison

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Now, more than ever, we need innovative housing solutions to meet the needs for today’s families – and tomorrow's. The high cost and lack of available new living space presents today’s families with unique housing challenges. There’s a solution we’re all familiar with and homeowners have called them carriage houses or mother-in-law suites for decades. But, today they have a new name: Accessory Dwelling Units, or ADUs.

AARP Wisconsin supports updating regulation of Accessory Dwelling Units (ADUs) in Madison. The updates to amend Section 28.151 and 28.211 of the Madison General Ordinances to allow construction beyond just behind single-detached dwellings and remove the owner occupancy requirement are an important step to help families stay close. ADUs provide a unique housing solution to today’s challenges. They can be utilized for caregiving services, keep multi-generational families together, or give homeowners the option to rent part of their property in order to afford their primary residence. And now, ADUs represent an affordable housing option so people can live independently longer close to family and age in place.

What are Accessory Dwelling Units?
An Accessory Dwelling Unit (ADU) is a fully independent home with its own kitchen, bathroom(s) and sleeping area on the same lot as the main house. They’re a smart match for smaller households and can be created through basement or garage conversions, additions, or new construction of back yard ‘tiny homes. Typically, most residential zones requires that they be discreetly located to fit in well with the surrounding neighborhood. Often times, they’re invisible from the street. However, you should check local regulations to be sure your project is in compliance. Creative design of ADUs can take many different forms and styles, they can fit discreetly into all sorts of communities, including suburban subdivisions, row-house streets (either with or without back alleys), urban neighborhoods — and, of course, large lots in rural areas. To learn more about ADUs visit

More About ADU Value
• According to a 2021 Trends in Home and Community Preferences survey, 79% of adults 50-plus wish to stay in their communities. ADUs give them the flexibility to do so.
• ADUs may provide a lower-cost alternative to assisted living, which, according to research by Genworth, can cost seniors and their families in Dane County over $4,500 per month.
• Because of city ordinances and construction regulations, ADUs will blend into the neighborhood.

*This information is provided for educational purposes only. For more information, please contact AARP Wisconsin at

How Accessory Dwelling Unit Help Families
ADUs (accessory dwelling units), also called in-law units, English basements, or alley flats, can provide more housing options to community members.

Why AARP Wisconsin Supports the Ordinance Change
With respect to the two proposed changes to the existing sections, AARP supports both. Allowing ADUs to be constructed on lots currently built with up to eight dwelling units provides options for a variety of homeowners and enhances Missing Middle Housing options. Support for construction in various residential zoning districts is found in the AARP Accessory Dwelling Units Model State Act and Local Ordinance publication.

AARP’s support for no owner-occupancy requirement falls within two camps: equal treatment and financing implications. Madison does not require the owners of the primary unit main house to live in it. If it is permissible for owners of a detached single dwelling unit to rent out their home (and not live in it), in addition to being restrictive, then it is unfair and illogical to apply different rules to the ownership of ADUs. Either require all owners to occupy their own home or none, but it appears that in creating different rules for ADUs, we are treating ADUs as an inferior form of real estate.

Owner-occupancy requirement could also have financing implications. Let’s be frank, ADUs are not inexpensive to build, and most homeowners will have to finance the construction. When doing this, the security for the financing is the property itself.

As a condition of the loan, the homeowner agrees that the financial institution can take possession of the property if the homeowner fails to make payments, also known as foreclosure. If the bank forecloses, it cannot “occupy” or reside in the property as the owner. For that reason, lending institutions will not provide financing if there is an owner occupancy requirement. It is important to create easier regulations for homeowners to exercise their property rights. 

Download More from AARP: Accessory Dwelling Units
The ABCs of ADUs: Free guide to how accessory dwelling units create more housing options for people of all ages.

Great Neighborhoods for All Ages
Need more local data about housing or transportation your community? Visit the Updated AARP Livability Index. The AARP Livability Index scores neighborhoods and communities across the U.S. for the services and amenities that impact you the most.

About AARP Wisconsin
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