Policy Studies

Unlocking the Missing Middle: Proven Practices for Affordable, Higher-Density Housing

The School of Cities, University of Toronto, presents a comprehensive report on enabling “Missing Middle” (MM) housing development—a key solution to Canada’s housing affordability and density challenges. This report explores proven and promising practices from Canada, the U.S., and New Zealand, offering actionable insights to overcome barriers and enhance reforms for MM housing.

What is Missing Middle Housing?

MM housing bridges the gap between single-family homes and high-rise buildings, encompassing:

  • Accessory Dwelling Units (ADUs): Small detached or attached homes.
  • Multiplexes: Multi-unit conversions of existing homes or purpose-built flats.
  • Small Apartment Buildings: Developments up to four storeys, often on a single lot.

Designed for households earning 51–120% of the area median household income (AMHI), MM also includes affordable options for low-income households through ADUs, rooming houses, and nonmarket housing. MM housing was once a staple of North American cities, offering compact, diverse housing types in central, well-serviced locations before exclusionary zoning and gentrification limited its availability.

Why Missing Middle Housing Matters

The benefits of MM housing are transformative:

  • Affordability: Smaller homes at moderate price points.
  • Diversity: A range of home sizes, from studio ADUs to four-bedroom apartments.
  • Accessibility: Proximity to public transit, amenities, and employment hubs.
  • Sustainability: Energy-efficient designs and reduced travel distances.

The Road Ahead

The report outlines barriers to MM development—legislative, administrative, and financial—and identifies enablers to support its growth. Drawing from case studies in Auckland and other cities, it demonstrates how increasing MM housing supply can reduce housing costs and improve access for low-income tenants.

📖 Discover how Missing Middle housing can reshape Canadian cities. Read the full report now to explore proven practices, global success stories, and actionable strategies to bring MM housing to life.

Explore how cities across Canada are embracing accessory dwelling units (ADUs) with the School of Cities, University of Toronto’s interactive ADU Tracker. Dive into charts and interactive maps that reveal the take-up of detached and attached ADUs in 16 major urban centres, alongside summaries of municipal and provincial policies shaping this housing innovation.

With federal Housing Accelerator Fund (HAF) investments boosting housing supply to address population growth and affordability, this tool offers insights into ADU trends, permitting data from 2014–2023, and policy analysis. From Toronto to Calgary, see how ADUs are shaping the future of housing—and learn how your city can do the same.

Developed by Ahmad Al-Musa, Priya Perwani, Muhammad Khalis Bin Samion, & Jeff Allen.

Unlocking Alberta’s Middle Housing Potential


In partnership with the Canadian Urban Institute and mddl, and funded by the Alberta Real Estate Foundation, this report dives into the transformative possibilities of middle housing in Alberta. From innovative strategies to overcome barriers to scaling production, to practical solutions for unlocking gentle density across the province, this collaboration is a must-read for anyone passionate about housing solutions. Curious about how middle housing could reshape Alberta’s communities?

Click through to discover the findings and recommendations shaping the future of attainable, diverse housing options!

As housing affordability challenges escalate, an increasing number of middle-income renter households are facing cost burdens. In response, states and localities are implementing policies to address these needs. While these programs aim to expand affordable housing in high-cost areas, they face criticism for potentially diverting resources from lower-income households.

This new research paper from the Harvard Joint Center for Housing Studies explores these middle-income housing initiatives, evaluating their goals, benefits, and the tradeoffs involved. By examining eleven state and local programs, the paper finds these initiatives are becoming more common across diverse regions, primarily focusing on expanding housing supply for the “workforce” based on area median income.

However, these programs often fall short of assisting the most cost-burdened renters, who are predominantly lower-income. Moreover, the demographic disparity, with middle-income renters being disproportionately white, raises concerns about reinforcing racial inequities.

The paper recommend designing middle-income housing programs that do not detract from resources for the lowest-income households, operate in areas where the market fails to serve middle-income renters, and provide additional benefits to lower-income communities. Read the full report to understand the complexities and potential solutions in addressing middle-income housing needs.

In 2023, the Terner Center published “Making It Pencil: The Math Behind Housing Development” to assist policymakers in understanding the financial feasibility of large-scale, for-rent midrise apartment buildings. However, recent state and local land use reforms have focused on smaller-scale housing in lower-density neighborhoods, including accessory dwelling units (ADUs), duplexes, and fourplexes, often referred to as “missing middle” housing. States like California, Oregon, and Montana, along with cities such as Minneapolis and Portland, have introduced legislation and rules to promote this housing growth.

This policy paper employs the methodology from our 2023 report to analyze the development characteristics of missing middle projects. Through a series of project pro forma case studies across four California markets, the report finds that many missing middle housing types are not financially feasible, with four-unit ownership buildings being the most challenging to develop. Despite these challenges, missing middle housing can play a crucial role in providing entry-level homeownership and naturally affordable rental options. It is imperative for local and state policymakers to reexamine regulations that hinder the development of missing middle housing, such as lot size, parking, and insurance requirements.

Nestled near the Elders Centre in the Tl’etinqox Community, six cabin-like homes are placed to form a circle to represent the four sacred directions, the cycle of the seasons, the cycle of life and more, and to encourage community gathering.

Tl’etinqox began to develop Elders Cabins in 2019 to honour the intentions, prayers, and needs of their Elders by providing safe and affordable living spaces for them to age in place, at the heart of the community. Elder tenancy applications opened for the cabins in September 2020.

The below is an extract from Small Housing’s Gentle Density Housing Bylaw Guide: A pathway for local governments, a guide that aims to provide local governments with a roadmap for changing their zoning bylaws to allow gentle density housing, based on experiences from jurisdictions leading the way. It was developed with support from CHMC.

Key insights:

Zoning bylaws across Canada vary widely in structure and content, reflecting applicable legislation and calibrated to the local conditions of the communities they serve to regulate. This diversity of bylaw formats makes adopting a ‘one-size fits- all’ Gentle Density Housing zone inappropriate in most circumstances.

Rather, as the below charts outline, bylaw changes must reflect local conditions, while allowing more flexibility in the housing options that are permitted in residential neighbourhoods. Some communities will have the resources to do extensive research and background work as part of a detailed approach to zoning reform, and others may choose to take a simpler path in adopting basic zoning parameters that will support gentle density housing.

There is value in learning from the approaches already in use by leading communities, and the table below provides precedent infill zones in select larger municipalities in British Columbia and Alberta.

Key insights:

In November of 2023, the province of British Columbia released their “Homes for People Plan” that drastically reduced zoning and municipal barriers to the creation of gentle density homes. In summary, new legislation requires all local governments in British Columbia to update their zoning bylaws to allow up to three to four units in all single-family zones and up to six units for properties with frequent bus service.

This resource, developed by the province, is intended to help local governments and their community members understand the legislative changes introduced related to small-scale, multi-unit housing (SSMUH).

Note: The information in this tool kit is for guidance only and is not a substitute for provincial
legislation. It is not legal advice and should not be relied on for that purpose.

Key insights:

This report investigates the potential for infill development in Mississauga to accommodate the region’s population growth projections and ensure that new development does not infringe on the urban greenbelt.

The report outlines:

  • Mississauga could add approximately 174,000 new residential units (at an average unit size of over 1,000 sq.ft.) via low- and medium-density intensification.
  • Through this approach, Mississauga could accommodate 435,000 new residents.
  • This is enough housing to support Mississauga’s growth projects, and to also accommodate approximately 85% of Peel Region’s assigned growththrough to 2041.
  • This housing can be delivered without the consumption of new greenfield land, reducing the need to encroach into the Greenbelt

This report is authored by Graham Haines and Brianna Aird of Toronto Metropolitan University.

Key insights: Explore a comprehensive overview of details and technical resources to support the implementation of Bill 35 – Short-Term Rental Accommodations Act, Bill 44 – Housing Statutes (Residential Development) Amendment Act and Bill 47 – Housing Statutes (Transit-Oriented Areas) Amendment Act that have been provided to local governments by the Provincial Government of BC Housing.

Resources include:

  • Key timelines for local planners
  • What to know about the regulations and policy manuals, including details on Small-Scale Multi-Unit Housing Provincial Policy Manual and Site Standards
  • Summary slides about the regulations and policy manuals