very small houseGrowing in popularity since 2018, Additional Dwelling Units are small residential units built by homeowners on existing properties.

Centre for Cities, Cross Border Institute supporting community partners on federally funded housing data research

Additional Dwelling Units (ADUs) — also called secondary suites, granny flats, or mother-in-law suites — are small residential units built by homeowners on their existing property, usually in backyards or laneways. They have grown in popularity in Ontario since 2018 when the provincial government amended legislation to allow municipalities to permit the units to help increase housing supply.

A number of municipalities, including the City of Windsor, have created zoning bylaw provisions to allow ADUs over the years, but data tools to support their design, approval, and construction have been limited. After receiving proof of concept funding from the Canada Mortgage and Housing Corporation (CMHC) in 2021, a Windsor-based team led by Family Services Windsor-Essex developed an ADU data tool: The online interactive mapping tool allows users to see if it is possible to build a detached ADU in compliance with the local zoning bylaws on an individual property.

Last week, $2.2 million in funding was announced by Windsor-Tecumseh MP Irek Kusmierczyk to support the tool being scaled nationally over the next year and a half. The tool will provide data on the 100 largest municipalities across Canada. The funding comes through CMHC's Housing Supply Challenge, which funds projects aimed at supporting innovative solutions to Canada’s housing crisis.

The ADU project is led by Sarah Cipkar, a consultant, doctoral student in planning at the University of Toronto, and local developer, and Frazier Fathers, a local consultant and researcher through Family Services Windsor-Essex. Both are also UWindsor Masters of Arts grads in political science. Windsor law professor and Centre for Cities director Anneke Smit and engineering professor Hanna Maoh, associate director of the Cross-Border Institute, round out the working group and have co-supervised several students whose work contributed to the project.

Law JD students Shereen Arcis, Jackson Brown, and Daanish Shah provided research on the policy, financial, and physical aspects of ADUs. A blog post on their policy aspects, written by Arcis, was published earlier this week on the Centre for Cities website.

Law professor Laverne Jacobs was a member of the 12-person advisory committee of community members and stakeholder organizations providing input and oversight for the project in its first phase.

Civil engineering PhD candidate Terence Dimatulac worked with Dr. Maoh to develop a GIS model to calculate the total buildable ADU area of residential properties. Dimatulac also conducted the spatial analysis needed to create the GIS layers used in the development of the online tool.

“We are excited to move on to the next round and scale our proof concept across Canada,” says Fathers. “The partnership with the University of Windsor was invaluable and we are exploring how we will continue this partnership in the next phase of the project.”

Dr. Smit cites the project as an example of the potential of collaborations between UWindsor researchers and community partners.

“By working together we’re able to leverage our respective strengths, and ensure that the output is both relevant to the community and informed by existing research and best practices,” she says.

Fathers and Arcis joined Dan McDonald on the AM800/Centre for Cities citybuilding segment earlier this week to discuss the project.

On Thursday, the Centre for Cities hosted a demonstration and discussion of the project led by Cipkar and Fathers, followed by a question-and-answer session on the tool and the potential for ADUs. The recording is available on the Centre for Cities website.