Plan #21-0003: A Two-Unit Duplex Built for Rental Income and Multigenerational Living
If you've been looking for a home that can pay part of its own mortgage, house two generations of your family under one roof, or turn a narrow lot into two full rental units, Plan #21-0003 was drawn with exactly that in mind. It's a compact two-unit duplex that stacks a comfortable 1-bedroom suite on the main floor over a bright 2-bedroom suite below, two complete, self-contained homes in a footprint just 20'-8" wide.
Here's a closer look at the plan, who it suits, and how it fits into Ontario's push for more flexible housing.
What you get with Plan #21-0003
| Detail | Specification |
|---|---|
| Type | House (Duplex) — two self-contained units |
| Total finished area | 1,680 sq. ft. (840 sq. ft. per unit) |
| Configuration | 1-bedroom unit + 2-bedroom unit |
| Bathrooms | 2 (one per unit) |
| Overall width | 20'-8" |
| Overall depth | 55'-9" (including front and rear decks) |
| Outdoor space | Covered front deck |
| Laundry | In-suite laundry in each unit |
Each unit is a genuine standalone home with its own kitchen, living and dining space, full bathroom, and private laundry, not a bedroom-and-a-hotplate arrangement. That separation is what makes the plan work equally well for tenants, extended family, or a mix of both.
The main-floor unit (1 bedroom)
The upper unit opens into an airy, open-concept kitchen, dining, and living area that runs the width of the home, with a private larger 8bedroom, a full bathroom, and a dedicated laundry closet tucked off the hall. A covered front deck extends the living space outdoors, the kind of spot that makes a smaller footprint feel generous.
The lower unit (2 bedrooms)
The lower level is a full two-bedroom home in its own right: two smaller bedrooms, a full bathroom, an open kitchen and living room, a dining area, and its own laundry. At 840 sq. ft., it lives far larger than its size suggests thanks to the open layout and the long, light-friendly window wall.
Who this plan is for
The house-hacker. Live in one unit, rent the other, and let the rental income offset your mortgage. A stacked duplex like this is one of the most approachable ways to get into ownership while building equity.
The multigenerational family. Keep aging parents or adult children close but independent — separate entrances, separate kitchens, separate laundry, shared lot. The 2-bedroom unit gives a family the room to grow, while the 1-bedroom suite suits a grandparent or a returning young adult.
The small investor. Two rentable units on a single narrow parcel is efficient use of land and a strong long-term hold. In-suite laundry and open layouts in both units make each easier to lease and easier to keep leased.
The narrow-lot owner. At just 20'-8" wide, Plan #21-0003 is purpose-built for tight urban infill lots where a wide home simply won't fit.
Duplexes and Ontario's additional residential unit rules
Ontario has spent the last few years making it dramatically easier to add homes to existing residential lots. Under the province's additional residential unit (ARU) framework introduced by Bill 23, the More Homes Built Faster Act, most serviced residential lots in the province now permit up to three residential units as-of-right, meaning a compliant design can proceed without a rezoning application. The province also limits municipalities from imposing minimum unit sizes and reduces parking requirements for these units.
A two-unit building like Plan #21-0003 sits comfortably within that framework. Ontario's Building Code recognizes a secondary suite as a self-contained dwelling unit in a building that contains only one other dwelling unit, which is precisely how this stacked duplex is arranged. That makes it a clean fit for owners who want a legal two-unit home, whether as a new build or as part of an ARU strategy on an existing property.
A few important notes:
- The zoning details are local. As-of-right permissions, setbacks, lot coverage, servicing, and parking are confirmed at the municipal level, and they vary from one township to the next. Always verify what your specific lot allows before you build.
- Two units means qualified drawings. Because this is a two-unit home, your building permit set needs to meet Ontario Building Code requirements for fire separation, egress, and sound control between the units. Our plans are prepared by a BCIN-licensed designer and drawn to satisfy those requirements.
- We can check your zoning for you. Not sure whether your lot qualifies or how many units it allows? Our zoning search service does the legwork so you know where you stand before you commit.
This is general information, not legal or planning advice — your municipality has the final say on what's permitted for your property.
Ready to build — and adaptable to your region
Plan #21-0003 is one of our pre-designed plans, which means it's ready to move forward quickly and priced well below a fully custom set. When you order, we adjust the structure for the snow and wind loads specific to your region of Canada, and your finished plans arrive by email, within two weeks if there are no additional personalized design changes.
Want to tweak the layout, flip the unit mix, or reconfigure the exterior? That's exactly what our custom design and e-design services are for. Think of a pre-designed plan as a proven starting point, one you can make your own.
Frequently asked questions
Is Plan #21-0003 a duplex or a house with a secondary suite? Both descriptions fit. It's a two-unit building with a 1-bedroom unit stacked over a 2-bedroom unit. Under Ontario's Building Code, a self-contained second unit in a building with only one other dwelling unit is defined as a secondary suite, so this plan works whether you're building a purpose-built duplex or adding a legal second unit.
How big is each unit? Each floor is 840 sq. ft., for 1,680 sq. ft. of total area (based on exterior measurements). The upper unit has one bedroom; the lower unit has two bedrooms. Each has its own full bathroom, kitchen, living and dining area, and in-suite laundry.
Will this plan fit a narrow lot? Yes. The overall width is 20'-8", which makes it one of our better options for narrow urban and infill lots where a wider home won't work.
Can I rent out one unit and live in the other? That's one of the most popular ways to use this plan. Living in one unit while renting the other, often called house-hacking, lets the rental income help cover your mortgage, subject to your local rental and licensing rules.
Can I build this anywhere in Ontario? Ontario's ARU rules permit up to three units as-of-right on most serviced residential lots, but setbacks, lot coverage, servicing, and parking are confirmed municipally and vary by location. We recommend confirming your lot's zoning first, our zoning search service can handle that for you.
How do I get the plans, and how long does it take? Order the plan through our shop and you'll receive your drawings by email, usually within about two weeks. We adjust the plan for the snow and wind loads specific to your area of Canada before delivery.
Explore Plan #21-0003
Ready to see if this two-unit duplex is the right fit for your lot and your goals?
View Plan #21-0003 and download the brochure →
Not quite right? Browse all of our pre-designed plans or get in touch — we also offer custom design, renovations, zoning searches, and e-design services.