Duplex, Triplex or Fourplex: Choosing the Right Unit Count for Your Lot
The first question most owners ask is how many units they can build. The better question is how many units the property can support well, because the gap between those two answers is where projects get into trouble.
What the lot allows
Zoning sets the permitted use and the number of units on a residential lot, and setbacks, coverage and height limits decide how much building actually fits. A wide, deep lot may comfortably take four units. A narrow infill lot may take three, or two generous units rather than three cramped ones.
Parking belongs in this step, not in a later conversation. If the property cannot provide the parking the units need, the unit count has to come down or the layout has to change.
What the market supports
Unit mix matters as much as unit count. In a student-oriented neighbourhood, three or four smaller units often lease faster than two large ones. In a family neighbourhood, larger two-bedroom and three-bedroom suites with storage and outdoor space are what tenants ask for.
Building the wrong mix is an expensive way to learn the local market. We look at who rents nearby, what they rent, and how the finished building will compare before the unit count is locked in.
What the numbers support
Each additional unit adds revenue and cost. Extra units mean more kitchens, more bathrooms, more mechanical, more fire separation and more parking, plus the site work that comes with a larger building.
There is a point on every lot where the next unit stops paying for itself. Finding that point is the whole exercise, and it is a better use of a week of analysis than discovering it two months into construction.
How we decide, in order
- Feasibility review of the address: zoning, lot dimensions, servicing and parking.
- Preliminary unit mix and layout options that fit what the lot allows.
- Cost range and expected rents for each option.
- A recommendation on unit count, with the reasoning in writing.
That sequence is the same whether the property is in Toronto, Hamilton, Burlington or Oakville. What changes is the answer.
The units themselves
Once the count is settled, the details decide how the building performs. Separate entrances, individual laundry, real storage, sound separation and metering are not extras, they are what keeps good tenants in place and reduces turnover.
You can see how those decisions played out on completed buildings in our project case studies.