Why Toronto's missing middle is the most under-built housing category in the city

What "missing middle" actually means

"Missing middle housing" is the category of buildings that sit between a detached house and a high-rise apartment tower. Duplexes, triplexes, fourplexes, sixplexes, low-rise walk-up apartments, courtyard buildings, stacked townhouses — anywhere from two to about twenty units, usually on a single residential lot or a small assembly of lots, almost always low-rise.

The term was popularized by the planner Daniel Parolek in the early 2010s, but the building typology is much older than the label. Walk through The Annex, Riverdale, or Cabbagetown and you'll see it everywhere: brick walk-ups carved into older streetscapes, triplexes with side stairs, four-storey courtyard apartments tucked between Victorians. They were the workhorse of pre-war Toronto.

Why it disappeared

Three things happened, broadly in sequence.

Postwar zoning rewrote the rulebook. Cities across North America, Toronto included, adopted use-segregated zoning in the postwar period. Vast swaths of low-rise neighbourhood land were designated for single-family detached only. The fourplex on the corner became, on paper, a non-conforming legal grandfathered relic — something the bylaw allowed to remain but would not permit you to replicate.

Lending and the development industry followed. Lenders learned to underwrite two things efficiently: single-family houses and large apartment buildings financed under CMHC's multi-residential programs. The fourplex sat in an awkward middle: too big for residential underwriting, too small for the institutional book. Builders followed the financing, and the typology fell out of the development industry's muscle memory.

Neighbourhood politics calcified the status quo. Once a neighbourhood was zoned single-family, the bar to upzone any individual lot was a public, contested rezoning process. Add a few decades of organized opposition, and the city's planning system effectively froze the residential land use map.

The compounding effect: Toronto kept growing, but it grew up — towers on avenues and at transit nodes — and out — sprawl on the urban edge. The middle was empty.

Why it's coming back

Three forces are now pushing in the other direction.

Zoning reform — and it's still moving. The City's Expanding Housing Options in Neighbourhoods (EHON) program rewrote the rulebook in stages. The 2023 city-wide bylaw permitted up to four units on virtually every residential lot; garden suites and laneway houses were legalized across all residential zones; and in 2024 Council went further, permitting small apartment buildings of up to six storeys and as many as sixty units on lots fronting major streets. In June 2025 came the next step: sixplexes as-of-right in nine wards (OPA 818), up to four storeys — followed by Council waiving development charges and parkland dedication entirely on multiplexes up to six units, one of the City's Housing Accelerator Fund commitments. A citywide sixplex rollout is now under study for 2026. See our 2026 sixplex rules guide for the ward map and waiver details. The language is technical; the effect is profound — the same lot that once allowed a single house can now, in the right location, support a building an order of magnitude larger. See our post-2023 zoning guide for how the layers stack.

Demographic demand. Toronto household formation outpaces tower delivery in the family-rental segment. A young family wanting three bedrooms, ground-floor access, and a yard can't make the math work in a downtown condo and is increasingly priced out of detached. The missing middle is the typology that fits — and there's almost no purpose-built rental at this scale on the market.

Density without the tower. The numbers are better than most people assume. On a standard 25-foot lot we will routinely design a six-unit building plus a laneway suite — seven homes where there used to be one. And frontage isn't even the variable that matters most: for the larger buildings, depth sets the ceiling. 91 Barton carries eleven units on 25 feet of frontage because the lot runs 160 feet deep. On a 30-foot lot, our current designs typically yield ten or more units. None of it reads as a tower from the sidewalk: the massing stays low-rise and the street absorbs the density without the disruption a high-rise creates. The political coalition gentle density builds is meaningfully different from the one a tower can build.

Who builds it now

Large institutional developers — pension fund-backed apartment owners, REITs, public companies — generally won't touch a six-unit infill project. The deal sizes are too small relative to the overhead of their underwriting, design, and construction stacks. There's a real fixed-cost floor below which it doesn't make sense for them to operate.

What's emerged instead is a small layer of specialist operators who do this work deliberately. We're one of them — but we've taken a different path from most of the field. The easy version of this business is the repeatable template: pour the same fourplex onto lot after lot and let volume do the work. We don't build that way. Every Green Street site is designed from scratch to extract the maximum the zoning will allow — more square footage, more units, a laneway suite where the lot permits one — because that is what de-risks the project and compounds the long-term return. What lets us do that without inflating the budget is a decade of relationships: the trades, consultants, and planners we work with on every project keep our costs among the lowest in the market — and our build times at seven to ten months — even though no two of our buildings are the same.

Where we've concentrated is the part of this market most operators avoid: the approvals. Pushing a lot past its as-of-right envelope — a Committee of Adjustment variance, a rezoning, a Major Streets application — is where projects stall or die. It's also where the value is created. Our approvals track record is, frankly, the thing we're best known for: more than ten projects taken through approval, five of them all the way through appeal, without a single refusal. It's the reason landowners bring us their hardest sites rather than their easiest ones.

The case for purpose-built rental at this scale

A multiplex held as purpose-built rental, designed and built by an operator who plans to own it long-term, is a different building from one carved into individual condominium units and sold off.

The owner-operator has every incentive to over-build the envelope, the systems, and the finishes — to spend the marginal dollar on durability rather than on the showsheet. Maintenance cost is the operator's cost. Tenant retention is the operator's revenue. The alignment between build quality and long-term return is direct.

The condo conversion, by contrast, optimizes for the day of the sale: glossy finishes, deferred-but-still-passing systems, and a balance sheet that walks away at closing. Both are legitimate, but if you care about what the building looks like in twenty years, the purpose-built rental approach is the one that produces it.

Where this goes

We think the next decade in Toronto is defined, in housing terms, by how far operators can push the envelope the EHON reforms opened — particularly the Major Streets allowance, which quietly turned thousands of ordinary residential lots into sites that can carry a six-storey, sixty-unit building. The upper end of the missing middle is where we've chosen to build, because it's where the gap between what a lot is zoned for and what it could deliver is widest — and closing that gap is the whole job.

For more on the building programs themselves, see our page on large multiplexes — and our project portfolio for the buildings. If you're weighing a smaller scheme, our fourplex and sixplex pages cover those too.

Frequently asked questions

What is missing middle housing?

Missing middle housing is everything between a detached house and a mid-rise apartment tower: duplexes, triplexes, fourplexes, sixplexes, garden and laneway suites, and small walk-up apartment buildings. The name refers to the fact that for most of a century these building types were effectively illegal to build in most of Toronto's residential neighbourhoods — so almost none were.

Why is it called "missing"?

Exclusionary zoning, introduced in Toronto beginning in 1912, restricted most residential land to single-family houses. The multiplexes that exist in neighbourhoods like The Annex largely predate those rules — and for decades nothing new could legally join them. The typology went missing from the housing supply, not from demand.

Is missing middle housing legal in Toronto now?

Yes. Since 2023, up to four units are permitted as-of-right on virtually every residential lot city-wide; since June 2025, up to six units in nine wards; and small apartment buildings are permitted on designated major streets. Development charges are waived on multiplexes up to six units. Toronto has moved from prohibiting this housing to actively subsidizing it.

Who builds missing middle housing in Toronto?

Mostly small and mid-sized specialist developers rather than the large firms that build towers. Green Street Flats has been building at this scale since 2018 — purpose-built rental multiplexes, designed, built, owned, and managed for the long term, with seven completed buildings and 200+ units in the pipeline. Our 321 St. George project was CoStar's 2025 Multifamily Development of the Year.

Does missing middle housing actually add much density?

More than most people assume. On a standard 25-foot Toronto lot, a well-designed program can carry six units plus a laneway suite — seven homes where there was one. With the right lot, considerably more. Multiplied across even a fraction of Toronto's roughly 70% of residential land zoned low-rise, the capacity is enormous — delivered without changing how a street feels.