Six units in Toronto. Three in Markham. Four in Ajax. Before any lot analysis, the first question is which side of the city line you're on — because the line is worth more than the lot.
We get calls every week from owners across the GTA with the same plan: "I've got a 50-foot lot, I want to build a sixplex." Whether that plan is brilliant or impossible depends less on the lot than on a boundary you can't see from the driveway. Housing rules are municipal — and the municipalities have made radically different choices.
| Municipality | Units as-of-right | The note that matters |
|---|---|---|
| Toronto | 4 city-wide · 6 in nine wards (+ garden suite) | Plus $0 development charges up to six units — the strongest multiplex rules in Ontario |
| Ajax | 4 | The 905's most builder-friendly outlier |
| Burlington | 4 | 2026 by-law; coach houses too |
| Markham | 3 | A 4-unit by-law was deferred in 2025 and remains unresolved |
| Pickering, Vaughan, Mississauga & most of the 905 | 3 | The provincial Bill 23 floor — on fully serviced lots only |
| Rural townships | Often effectively less | Well/septic lots don't even get the provincial 3 |
The number that matters isn't three or four or six in isolation — it's the distance to five, because five units is where CMHC's MLI Select financing begins: 95% loan-to-cost, 40-year amortization, land-as-equity, insured rates. A Toronto lot reaches five with a fourplex and a garden suite — building permits only. A Markham lot capped at three units cannot reach the program at all without a rezoning fight measured in years. Same owner, same savings, same ambition — completely different financial universe, decided entirely by which council the lot reports to.
What that means in dollars: a three-unit 905 project finances conventionally — 65–75% of cost, 25-year amortization, cash down payment. A five-door Toronto project largely finances itself. We routinely see the smaller Toronto building put its owner further ahead than a bigger 905 one, purely on financing structure.
None of this is permanent — the 905 is under the same provincial pressure Toronto was, and these numbers will move. But you build under the rules that exist, not the ones promised. When a municipality changes its by-law, we update this table the same week.
Send the address — we'll tell you the door count, the financing reality, and whether building or waiting is the honest answer.
Get a Site ReadMunicipal rules verified September 2026 and subject to change — always confirm current by-laws with the municipality before acting. Not legal or financial advice.