How ADUs could transform Chicago into a more affordable, accessible place to live

Chicago offers a diverse mix of places to live, from soaring high-rises to more modest multi-unit courtyard buildings and single-family bungalows. Soon, state and local lawmakers could vote to bring back an entire category of housing after a decades-long ban: the accessory dwelling unit, or ADU.

What is an ADU?

An accessory dwelling unit is a secondary, smaller residence located on the same property as a traditional single-family home or multi-flat building. In Chicago, the most visible examples are the vintage coach houses still found over the garages of some older residences. But ADUs can come in other forms—including units in basements and attics, rear additions, or standalone backyard cottages (also known as granny flats).

A 1950s-era ordinance made accessory units illegal in Chicago. It stemmed from a fear of overcrowding during a period of rapid population growth following World War II. While existing ADUs were grandfathered in under the rule, many coach houses—especially those in affluent North Side communities like Lincoln Park and Lakeview—were demolished to make way for rear additions or much larger single-family mansions.

Why bring back ADUs now?

Today, Chicago faces the exact opposite set of circumstances which led to accessory units being outlawed in the 50s. Population growth is slowing, and an alarming number of residents in disinvested neighborhoods are simply moving away. At the same time, affordability remains a real concern. Bringing back ADU’s has the potential to help alleviate both issues.

For starters, adding an accessory dwelling unit can benefit a homeowner by increasing the value of their property as well as create a secondary revenue stream if they choose to rent the unit out. That money can help mitigate tax hikes and other cost burdens facing Chicago’s homeowners. By bringing financial stability to a greater number of properties, ADUs could go a long way to slow the pace of demolition of Chicago’s older two- and three-flat buildings.

It’s not just property owners that stand to benefit from accessory units. An increase in the supply of smaller and less expensive living options can provide much-needed relief from the affordable housing crisis currently gripping the nation. Zillow predicts that the Chicago metropolitan area is expected to build roughly 563,000 homes by 2040. But if just one in every ten single-family lot added an accessory unit, that number could increase new supply by more than 237,000 over the same period.

New legislation in Springfield is paving the way

A big step toward bringing ADUs back to the Chicago area came in late February when Rep. Robyn Gabel introduced a short, straightforward bill to the Illinois House of Representatives prohibiting municipalities from outlawing ADUs outright. If approved, the measure would also prevent cities from imposing functional bans aimed at burdening accessory units with unreasonable regulations.

“It’s clear to a lot us all over the state, that many, if not all, communities in Illinois are struggling to provide affordable housing,” says State Representative Will Guzzardi, who serves the Logan Square neighborhood and is a sponsor of Gabel’s bill. Guzzardi tells Curbed Chicago that state lawmakers need to meet the challenge with “creative” policies and the legalization of ADUs have an important role to play.

“[Accessory units] represent a community-centered approach to creating more housing. The units can be used by aging parents who want to age in place, or by recent college graduates while they work to take the steps toward financial independence. It gives the individual families and homeowners of Illinois control over development in their neighborhoods,” Guzzardi says.

Courtesy Booth Hansen

Chicago is moving forward with own ADU legislation

While some municipalities like Evanston have already approved ADU regulations, the Chicago City Council still needs to sign off on the zoning rules and building regulations that will govern new accessory units and any existing units that may not be compliant.

A recommendation to legalize ADUs was a component of the city’s Five Year Housing Plan put forth by former Mayor Rahm Emanuel in 2019 and is being championed by the current Lightfoot administration.

“Taskforce after taskforce, we’ve all seemed to come to the same conclusion that this would be a good change,” says MarySue Barrett, President of the Metropolitan Planning Council, an organization that advocated for ADUs since the 1990s overhaul of the zoning code. “Now it’s just a matter of moving it forward. The stars are aligned, the groundwork has been laid.”

The city’s planning department has been at work on draft ADU regulations for roughly a year. In mid-February, the Daily Line reported that the legislation would be delayed at least another month as planners make revisions that would ensure that the expected influx of ADUs would be used primarily as long-term housing and not be overrun by short-term rentals like Airbnb.

ADUs can bring accessible living options to existing homes

Most Chicagoans probably associate ADUs with old-fashioned-looking coach houses atop garages, but new legislation should accommodate a wide variety of designs. Groups like the Urban Land Institute and the City Open Workshop have brought together planners, architects, and urbanists to discuss how ADUs will fit in the fabric of Chicago’s 77 neighborhoods and how to best accommodate residents of differents ages and abilities.

“These initiatives have engaged directly with architects to prepare for this new housing type,” says Steven Vance, director of urban planning at MAP Strategies and founder of Chicago Cityscape. “There is a growing need for universally-designed accessible housing, but many houses across Chicago have either five steps up or three steps down. If you can build an attached rear ADU on the ground floor, you eliminate the need for stairs.”

An accessory units can also be used to house an on-site caretaker for sick or elderly residents. It’s perhaps no surprise that one of the biggest proponents for ADUs nationwide is AARP.

What will the next generation of ADUs look like?

One group that’s played a particularly active role in envisioning Chicago’s ADU future is Booth Hansen. The local architecture firm recently produced a series of conceptual schematics illustrating the different types of ADUs that could potentially be allowed in the city.

“When it comes to ADU regulations, we think less is more,” says Mark Pomarico, an architect with Booth Hansen. “For example, if the city chose only to allow basement units or units above a garage, it would severely limit the number of properties that can support ADUs and limit which people can use them.”

Some of the more technical aspects of implementing ADUs is already in place, adds Booth Hansen’s James Young. “The city actually did a pretty excellent job in the latest building code to lay some of the groundwork for ADU adoption. It allows for greater use of wood construction, building closer to the lot lines, and a lower minimum basement ceiling height in anticipation of accessory dwellings.”

Courtesy Booth Hansen

The city will need to provide resources to help homeowners build accessory units

Many important questions remain, like how will a typical homeowner know if their lot is a good candidate for an ADU? Where do they find an architect? How do they work with the city to install the necessary utility hookups? And perhaps most vitally, how do property owners in the underserved communities that could potentially benefit the most from ADUs access the financing needed to build units?

“We’ve taken part in ongoing discussions about coming up with guides to help homeowners, such as developing a website or online tool kit that can get people on the right path,” adds Pomarico. “We’re asking these questions now so the rules are shaped in a way that anticipates the biggest hurdles. It isn’t just pie in the sky thinking.”

It’s too early to say when ADUs return to Chicago

Chicago’s ADU legislation could potentially be introduced to the City Council in as early as March and pass in April. It’s still unclear how long it may take for the rules to take effect and for residents to start building accessory units. Steven Vance tells Curbed that he anticipates a transition period once the ADU ordinance passes that will allow the city’s Building Department to get up to speed before it starts processing permits.

One major effect of a blanket approval of ADUs would be the elimination of single-family zoning across the city. Minneapolis recently adopted a similar zoning change as a means to address long term affordability, racial segregation, inequality, and climate challenges. The same concerns led to ADU legalization on the West Cost in states such as California, Oregon, and Washington—despite pushback from NIMBYs.

“Slowly and surely, more cities are adopting ADUs, more will be built, and we’ll realize armageddon isn’t going to happen,” said Dan Bertolet, of Seattle-based think tank Sightline Institute, to Curbed in 2018.