This Accessory Dwelling Unit post is part of our ongoing study of Chicago’s defining building forms and the history of our communities written in buildings. Read about Worker Cottages, Chicago Bungalows, Courtyard Apartment Buildings, Residential Hotels, Greystone Flats, Four-Plus-One Apartments, Fire Cottages, and Skyscrapers.
THE CHICAGO COACH HOUSE & ACCESSORY DWELLING UNIT RENAISSANCE IS HERE
The classic Chicago coach house and other iterations of Accessory Dwelling Units (ADUs) are set for a revival. This is due to a recent city ordinance and pilot project. These initiatives encourage residents to build new ADUs and update existing ones to meet code requirements, allowing them to return to the rental market.
Coach houses are detached, secondary dwellings built on the same property as the primary residence. ADUs have various colloquial names like “granny flats,” “mother-in-law suites,” and “coach houses.” They are typically basements or attics converted into separate dwellings with private entrances, full baths, and kitchenettes or full kitchens. They can also be new, smaller-scale buildings separate from the main house. These residential types have an interesting history, which we’ll cover later. But first, the exciting news: you are about to see a whole lot more of them!
Repealing a 64-year-ban on the typology, the Additional Substitute Dwelling (ADU) ordinance (propelled in part by Streets Blog Chicago’s Steven Vance) permits the building of ADUs and coach houses in five designated pilot zones. The zones are spread across Chicago’s north, northwest, west, south, and southeast areas. There will be an accompanying grant program to help lower- to moderate-income households make existing ADUs code-compliant. Additional funding will be offered if the ADU becomes accessible.
PILOT ZONES FOR THE NEW ADU ORDINANCE
- North zone covers parts of the West Ridge, Edgewater, Uptown, Lake View, North Center, and Lincoln Square community areas
- Northwest zone covers parts of the Albany Park, Irving Park, Avondale, Hermosa, Logan Square, West Town, Near West Side, and East Garfield Park community areas
- West zone covers parts of the East Garfield Park, West Garfield Park, North Lawndale, and South Lawndale (Little Village) community areas
- South zone covers parts of the Ashburn, Auburn Gresham, West Lawn, Chicago Lawn, Washington Heights, Roseland, Chatham, Greater Grand Crossing, Englewood, West Englewood, Washington Park, and Woodlawn community areas
- Southeast zone covers parts of the South Chicago, East Side, South Deering, and Hegewisch community areas
The reasons behind the ordinance, which went into effect in May of 2021, include helping provide a rental income source to homeowners to pay down mortgages and deal with rising property taxes and supporting multigenerational families and/or families navigating aging in place while encouraging a gradual building of affordable density in some of Chicago’s housing shortage-begotten neighborhoods.
BUILDING GRADUAL & AFFORDABLE DENSITY
The emphasis is on “gradual” density because the West, South, and Southeast pilot zones are limited to two ADU permits per block. Additionally, the secondary properties are not permitted to be listed on Airbnb or similar websites, and eligible properties must be owner-occupied. This will likely keep rental income streams from the ADUs hyperlocal and fund homeowners’ mortgages rather than going toward developers. Other stipulations include that new ADUs can be built only on homes at least 20 years old and must be built in areas zoned for multifamily residences.
Since the impetus behind the ordinance is partially to support lower-income residents, several affordability measures have been implemented. For properties building two or more ADUs, half of the units must be reserved for Chicagoans earning no more than 60% of the zone’s median income. Additionally, households earning up to 80% of the area’s median income can access loans of up to $25,000 for new coach houses or to restore existing ones.
What comes after the pilot project concludes? After three years, the Chicago Department of Housing (DOH) and the Department of Planning and Development (DPD) will analyze the results, and the ordinance will have a pathway to become citywide.
COACH HOUSE AND ACCESSORY DWELLING UNIT POSSIBILITIES
ADUs
The new ordinance opens a treasure trove of design possibilities around coach houses and ADUs. There is planning for aging in place for yourself or loved ones, providing proximate yet private lodgings for adult children or other relatives, and that is just the tip of the iceberg. ADUs and coach houses can also be used to house an artist or teacher’s studio space, an office for remote workers who crave live/work separation, a practice space for musicians, a live-in nanny or caregiver’s lodgings, a homeschool pod, or just a source of rental income to help pay off a mortgage, fund college, or retirement.
Part of the fun of designing or renovating coach houses and ADUs is that so many have interesting historical design details or layouts baked right in, given their longevity in Chicago’s urban fabric. It’s easy to forget that before cities were designed around cars, they were designed around horse-and-carriage set-ups. The coach house was originally designed to store a coach on the first level and often included living quarters for the coachman above.
Coach Houses
Generally reserved for those of a certain economic status, coach houses were auxiliary structures, usually constructed on the back of a lot behind the main house. When cars supplanted the horse-drawn carriage as the primary way to transport people, many coach houses were converted into garages. However, many of them don’t look like your average garage, sporting charming historical designs that match their accompanying structure. In the late 1950s, fearing that the post-war boom would overly densify the city, the construction of new coach houses, and indeed, all basement/attic residential conversions were banned, with existing ones grandfathered in with the caveat that no renovations could be executed on them. For a look at historic Chicago Coach houses, the Ask Geoffrey column offers excellent examples.
For new present-day coach houses, though, some design parameters will guide the process. Coach houses must be shorter than 22 feet above grade and smaller than 700 square feet. Additionally, the overall footprint cannot exceed 60% of the rear setback. Equally exciting is the lifting of the ban on more serious renovations to coach houses, which has been in place for over a half-century. This means existing coach houses can be fully renovated to meet the new parameters, perhaps allowing them to become taller and more spacious, and better meet the needs of their owners in a more modern and customized way.
MODERN COACH HOUSE DESIGN & ADU CASE STUDIES
Now that coach house and ADU projects have some room to breathe, Chicagoans are rapidly submitting permit applications for them, and moss currently has several projects underway.
Ravenswood ADU: New Construction
As the second phase of this residential renovation, the project shifts its attention to the back of the lot. We are demolishing the existing garage to make way for a new ADU, making the most of the expansive, double-wide lot.
The ADU is positioned to maintain privacy within the backyard while still feeling visually connected to it. Its massing and fenestration are calibrated to reduce overlook and preserve usable open space, creating a relationship between the two structures. A warm-toned stucco clads both the house and the ADU, adding texture with desert vibes. Above, a deep overhang shelters a balcony that extends living space outward and creates a connection to the back yard.
Site analysis diagrams and early schematic sketches mapping sun paths and prevailing winds. These studies informed the ADU’s placement on the lot and calibrated overhang depths to mitigate summer heat gain while preserving daylight.
LINCOLN SQUARE ADU
Lincoln Square ADU is a total rehab with a brand new addition and is classified as an ADU. We’re designing and building a coach house in the client’s backyard on top of an existing garage. The project will add a balcony and overhang that provides shade for residents enjoying the outdoors in the summer while also shielding the interior from the sun’s harsh rays via passive cooling. Since the site is already under construction, connecting services for the new construction is easier.
Below are the ADU renderings and site analysis sketches.
LOGAN SQUARE ADU
The historic carriage house on the lot of the Logan Square coach house, built in original brick and outfitted with a horse stable, is being restored and retrofitted to include a second story. The main, two-unit building will remain untouched. Challenges with this project include structurally supporting the new second story atop the original carriage house, which requires connecting utilities from existing on-site inputs.
Below are the ADU design and site analysis sketches.
EVANSTON ADU
For another project in Evanston, we are tearing down an existing well-worn coach house and building a new one on a different part of the lot. Based on our site analysis, the original coach house is not in an ideal location and would be better suited elsewhere on the property. The new structure, adjacent to the main house, will contain a garage with an Accessory Dwelling Unit built on top.
Below are ADU design and site analysis sketches
