Duplex vs triplex vs fourplex: which is right for your Toronto lot?

Toronto lets you build up to four units as-of-right on most residential lots — but more units isn’t automatically more profit. The right count depends on your lot, your budget and the rents your street commands. Here’s the framework we use.

The economics of each step up

• Duplex (2 units): the lightest build and the easiest conversion — often achievable within an existing house. Best when budget is tight or the lot is small.
• Triplex (3 units): the sweet spot for many mid-size lots — three rents usually cover carrying costs comfortably, and the build often still fits a conventional house form.
• Fourplex (4 units): the strongest income and best construction cost per unit, since foundation, roof and services are shared across four rents. Needs the lot, and the budget, to do it properly.

Five questions that decide it

• What does the lot physically support? Frontage and depth set the envelope before economics enter into it.
• What do units rent for on your street? Some neighbourhoods pay for large family units; others for more, smaller ones.
• What can you finance? Lenders size construction facilities differently at each scale — the jump to four units can change the financing conversation.
• Existing house: keep or replace? A sound structure may make a duplex/triplex conversion the fastest money; a tired one usually argues for building new to four.
• How hands-on will you be? Four doors is more management than two — factor it in or budget for property management.

The garden suite wildcard

On many Toronto lots you can add a garden suite or laneway house on top of the multiplex count — turning a fourplex decision into a five-unit outcome. It’s often the highest-return unit on the property because the land is already paid for.