Duplex vs Triplex vs Fourplex: Which Fits Your Vancouver Lot
All three fall under the same BC building code path and the same R1-1/SSMUH zoning rules. The choice between a duplex, triplex, and fourplex comes down to lot size, budget, and how much rental-income risk you want to carry. Here is the side-by-side comparison.
Side-by-side comparison
| Factor | Duplex (2 units) | Triplex (3 units) | Fourplex (4 units) |
|---|---|---|---|
| Building code path | Part 9 | Part 9 | Part 9 |
| Total project cost (Vancouver) | Lowest total, highest per unit | $1.0M–$1.7M (construction only) | $3.0M–$5.2M (all-in) |
| Vacancy risk per unit lost | 50% of rental income | 33% of rental income | 25% of rental income |
| Typical minimum lot fit | Most standard lots | Most standard lots | ~280 m² / 33×122 ft standard lot |
| CMHC owner-occupied financing | 5% down under $500K, 20% at $1M+ | Same tiers as duplex | Same tiers as duplex |
Cost figures for standard Vancouver lots, wood-frame construction, mid-range finishes. Financing tiers apply only up to a $999,999 purchase price; CMHC-insured mortgages are not available above that regardless of unit count.
What actually changes as unit count rises
- Cost per unit drops. One foundation and one roof spread across more units lowers the average cost per unit, which is why a fourplex is often the more efficient build once the lot supports it.
- Rental income risk spreads out. A duplex loses half its income if one tenant leaves; a fourplex loses a quarter. This is the main argument for building the maximum unit count a lot allows, not the minimum.
- Management complexity rises. More units means more tenant relationships, more maintenance calls, and more lease renewals to track.
- Lot size becomes the ceiling. Zoning does not cap unit count at two or three by default under SSMUH; a lot's actual area and frontage decide whether four units fit.
Frequently asked questions
What is the difference between a duplex, a triplex, and a fourplex?
A duplex has two dwelling units on one lot, a triplex has three, and a fourplex has four. Each unit is self-contained with its own kitchen, bathroom, and entrance. In BC, all three fall under the same Part 9 building code path and the same R1-1/SSMUH zoning framework, so the choice between them mostly comes down to lot size, budget, and how much rental-income risk a household wants to carry.
Which is cheaper to build: a duplex, triplex, or fourplex?
A duplex has the lowest total construction cost of the three, but the highest cost per unit, because it splits foundation and roof costs across only two units instead of three or four. A triplex in Vancouver runs $1.0 million to $1.7 million in construction cost for all three units; a fourplex runs $3.0 million to $5.2 million all-in including land. Cost per unit generally drops as unit count rises on the same lot.
How does rental income risk change between a duplex, triplex, and fourplex?
Losing one tenant in a duplex removes half the rental income overnight, since only one other unit remains. In a triplex, one vacancy removes a third of the income; in a fourplex, it removes a quarter. A fourplex spreads vacancy risk across more units, which is the main reason investors often prefer it over a duplex once the lot is large enough to support one.
Do duplex, triplex, and fourplex lots need different sizes in Vancouver?
Yes. A duplex fits on most standard Vancouver single-family lots regardless of size. A triplex needs enough lot area and frontage to clear the SSMUH three-unit tier, and a fourplex needs to clear the four-unit tier, which typically requires a lot near the standard 33-foot by 122-foot size (about 4,000 square feet) or larger. Smaller or irregular lots may cap out at a duplex or triplex even though the zoning technically allows more units elsewhere on the same street.
Which one should an owner-occupier choose?
An owner-occupier who wants to live in one unit and rent the rest typically gets the best rental offset from a fourplex, since three rented units bring in more monthly income than two, while still qualifying for CMHC's owner-occupied 1-to-4-unit financing rules. A triplex is a middle option when the lot cannot support four units or when construction budget is the limiting factor. A duplex suits an owner who wants only one tenant relationship to manage.
Can I build a duplex now and add units later?
Generally no, not without a second full permitting and construction process. A duplex, triplex, and fourplex are each their own building code submission and construction project; adding units after occupancy means a new development permit, new building permit, and new construction phase, not a simple addition. If a lot can support four units, it is almost always cheaper to build all four in one project than to build two now and two later.
Which sells for more: a triplex unit or a fourplex unit?
Individual unit sale prices in Vancouver are driven mainly by unit size and neighbourhood, not by how many total units share the lot, so a triplex unit and a fourplex unit of comparable size and finish sell in a similar range. The real financial difference between the two building types is total project cost and the number of income streams, not the per-unit resale price.
Does a fourplex cost more per unit to finance than a triplex?
Financing terms depend on total purchase price and occupancy plan, not directly on unit count, as long as the building stays at four units or fewer. Both a triplex and a fourplex can qualify for CMHC's owner-occupied 1-to-4-unit insurance if the purchase price is under $1 million; above that, both need 20% down under the same rules. The financing rules change sharply only when a project reaches five or more units and moves into CMHC MLI Select.
See what fits your lot
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