Journal

Duplex vs Triplex vs Fourplex in Vancouver: Which Fits Your Lot

By Costar ConstructionSeptember 25, 2026Updated October 17, 2026

A homeowner whose lot qualifies for a multiplex under Vancouver's R1-1 zoning still has a choice to make: build the fewest units the lot allows, or the most. A duplex, a triplex and a fourplex each sit at a different point on that scale, and each one trades cost, income risk and resale liquidity differently. This guide compares the three directly, using the zoning rules and cost figures covered in Costar's companion guides. For the rules, permit steps and ownership questions behind this choice, read the multiplex guide.

The Three Formats Side by Side

	Duplex	Triplex	Fourplex
Units on the lot	2	3	4
Minimum frontage	Varies by lot type	10 m (33 ft)	10 m (33 ft)
Income loss from one vacancy	50%	33%	25%
Cost per unit vs a single house	Lower	Lower still	Lower still
Total project cost	Lowest of the three	Mid	Highest of the three
Resale buyer pool per unit	Largest	Smaller	Smaller

Rental Income Risk

The clearest practical difference between these three formats is what happens to a landlord's income when one tenant moves out. A duplex has only two rental incomes to begin with, so losing one tenant removes half the property's rental revenue until it is re-leased. A fourplex spreads the same risk across four units, so a single vacancy removes a quarter of the income rather than half.

A triplex sits in between, losing a third of its income to a single vacancy. This math is a genuine reason investors lean toward a fourplex over a duplex when the lot supports it: each extra unit lowers the share of income that one vacancy removes.

Zoning Eligibility by Lot

Vancouver's R1-1 zoning ties the maximum unit count directly to a lot's frontage, covered in detail in Costar's zoning and permits guide. A 10-metre frontage supports 3 to 4 units, which covers a triplex or a basic fourplex, while a wider 13.4-metre frontage opens up 4 to 5 units. A narrower or irregular lot may not reach fourplex eligibility even where the total lot area looks sufficient, because the City's rules set the unit count by frontage first.

A specific lot's frontage may cap it at three units regardless of what the owner would prefer to build, which is why a feasibility review of the actual property comes before choosing a target unit count.

Duplex Plus a Laneway House, or a 3-Unit Multiplex?

Owners often ask whether they can build a duplex and add a laneway house behind it. The City's Low Density Housing Options How-to Guide (October 2025 edition, read from the Internet Archive copy saved January 11, 2026, because the City's site refuses automated requests) says a duplex "cannot be built in conjunction with a Laneway House". A laneway house is allowed only with a single detached house, and it cannot be strata-titled, so it cannot be sold on its own.

Two homes at the front and one at the back is a 3-unit multiplex. The guide says the multiplex rules count "the total number of units on the site as opposed to the number of units in each building", and the units may sit in one or more buildings. One development permit covers the whole site, and each building gets its own building permit. A 3-unit multiplex needs at least 10.0 metres (32.8 ft) of frontage and 306 square metres (3,293.8 sq ft) of site area. The guide also says a multiplex is new construction only: it cannot be made by adding a new building to a lot that keeps its existing house.

Cost Comparison

A fourplex costs more in total than a duplex on the same lot, since it has more total floor area, more kitchens and bathrooms (the most expensive rooms per square foot to build), and higher city fees charged per unit. The full cost breakdown explains what drives construction cost and which City fees apply.

The cost per individual home moves in the opposite direction: a fourplex's per-unit cost is lower than a duplex's, because both projects share the same land cost, but the fourplex spreads it across twice as many homes. This is the same economic logic behind multiplex housing generally. The trade-off is that a fourplex requires a larger total construction budget and a longer build to reach completion, so the lower per-unit cost comes with a bigger upfront commitment.

Resale Considerations

A duplex unit generally has a larger buyer pool than a triplex or fourplex unit, since more buyers in the Vancouver market are specifically shopping for a half-duplex than for a smaller multiplex unit. This is a genuine trade-off against the income-protection and lower per-unit cost advantages of a larger multiplex: a triplex or fourplex owner accepts a narrower resale market in exchange for those benefits.

Each format answers a different goal. A buyer prioritizing long-term stability and easier resale may prefer a duplex, while an investor prioritizing rental income protection and lower per-unit entry cost may prefer a triplex or fourplex, depending on which unit counts a specific lot's frontage actually supports.

Costar's Experience Across Unit Counts

Costar's Vancouver project gallery spans this range directly: a custom newbuilt duplex in Arbutus Quilchena at 2145 West 32nd, a 5-plex multiplex on East 40th Avenue, and a 6-plex multiplex in Killarney. That 6-plex project, "It Takes Two," won Best Multiplex Home at the 2024 Georgie Awards, presented by the Canadian Home Builders' Association of BC.

To find out which unit counts a specific lot supports and how the costs compare for that property, book a consultation with Costar's team.

Frequently asked questions

What is the difference between a duplex, triplex and fourplex?

A duplex holds 2 homes on one lot, a triplex holds 3, and a fourplex holds 4, each with its own direct exterior entrance under Vancouver's multiplex rules. All three fall within the 3 to 8 unit range the City defines as a multiplex, except a duplex, which is treated as its own separate housing type under Vancouver zoning rather than as a multiplex.

Which loses more rental income if one tenant moves out, a duplex or a fourplex?

A duplex loses half its rental income if one of its two tenants moves out, while a fourplex loses a quarter of its income if one of four tenants leaves. This vacancy math is a core reason many investors favour a fourplex over a duplex on a comparable lot, since a single vacancy has a smaller effect on total cash flow.

Does my lot qualify for a fourplex or only a duplex in Vancouver?

Unit count depends on lot frontage under Vancouver's R1-1 zoning: 10 metres of frontage supports 3 to 4 units, and 13.4 metres supports 4 to 5 units. A narrower lot may not reach fourplex eligibility even if its total area seems large enough, because the City sets the unit count by frontage first.

Is a fourplex more expensive to build than a duplex?

A fourplex costs more in total than a duplex on the same lot, because it has more floor area, more kitchens and bathrooms, and higher city fees charged per unit. The cost per individual home is lower in a fourplex than in a duplex, since the land cost is shared across more units, even though the total project budget is larger.

Which is easier to sell later, a duplex or a fourplex unit?

A duplex unit typically has a larger buyer pool than a fourplex or triplex unit, because more buyers are shopping for a half-duplex than for a smaller multiplex unit. A triplex or fourplex trades some of that resale liquidity for lower entry cost and stronger rental income protection against a single vacancy.

Can I build a triplex on a standard single-family lot in Vancouver?

Most standard single-family lots in Vancouver's R1-1 zone that meet the 10-metre frontage minimum qualify for 3 to 4 units, which covers a triplex. A specific lot's eligibility depends on its exact frontage, lot size, lane access and floodplain status, so a feasibility review confirms the actual number before design work starts.

How does unit count affect the construction timeline?

A larger multiplex generally takes longer to build than a duplex on the same lot, since more units mean more framing, more finishing work, and more coordination across trades. The permit timeline is similar across unit counts within the 3 to 8 unit multiplex range, but construction itself scales with total floor area and unit count.

What has Costar built across these unit counts in Vancouver?

Costar's Vancouver project gallery includes a custom newbuilt duplex in Arbutus Quilchena, a 5-plex on East 40th Avenue, and a 6-plex in Killarney, giving the company direct experience managing budget and schedule at different points across the duplex-to-multiplex range. See each project page for the details of that building.

Can I build a duplex and a laneway house on the same lot in Vancouver?

No. The City of Vancouver's Low Density Housing Options How-to Guide (October 2025 edition) says a duplex cannot be built together with a laneway house, and a laneway house is allowed only with a single detached house. To put three homes on one Vancouver lot, an owner builds a 3-unit multiplex, which needs at least 10 metres of frontage and 306 square metres of site area.

Is a duplex with a home at the back a triplex or a multiplex in Vancouver?

Vancouver treats three homes on one lot as a 3-unit multiplex, whether they sit in one building or in two. The City's Low Density Housing Options How-to Guide (October 2025 edition) says the multiplex rules count the total number of units on the site, and the units may be in one or more buildings. One development permit covers the whole site, and each building gets its own building permit.

Sources

Build a multiplex City of Vancouver, September 25, 2026
Low Density Housing Options How-to Guide (October 2025), read from the Internet Archive copy saved January 11, 2026 City of Vancouver, October 17, 2026
R1-1 District Schedule City of Vancouver, September 25, 2026

Keep reading

November 9, 2026

Create your dream home. Tell us about your project today.

Get a free estimate Book a free consultation

Duplex vs Triplex vs Fourplex in Vancouver: Which Fits Your Lot

The Three Formats Side by Side

Rental Income Risk

Zoning Eligibility by Lot

Duplex Plus a Laneway House, or a 3-Unit Multiplex?

Cost Comparison

Resale Considerations

Costar's Experience Across Unit Counts

Frequently asked questions

What is the difference between a duplex, triplex and fourplex?

Which loses more rental income if one tenant moves out, a duplex or a fourplex?

Does my lot qualify for a fourplex or only a duplex in Vancouver?

Is a fourplex more expensive to build than a duplex?

Which is easier to sell later, a duplex or a fourplex unit?

Can I build a triplex on a standard single-family lot in Vancouver?

How does unit count affect the construction timeline?

What has Costar built across these unit counts in Vancouver?

Can I build a duplex and a laneway house on the same lot in Vancouver?

Is a duplex with a home at the back a triplex or a multiplex in Vancouver?

Sources

BC's 20% Foreign Buyer Tax and New Multiplex Homes in Vancouver: Why We Think Families Should Be Exempt

Radon in Vancouver Homes: How to Test, and How to Build It Out of a New House or Multiplex

Architect or Building Designer? Who Can Design Your Vancouver House or Multiplex

Create your dream home. Tell us about your project today.

The Three Formats Side by Side

Rental Income Risk

Zoning Eligibility by Lot

Duplex Plus a Laneway House, or a 3-Unit Multiplex?

Cost Comparison

Resale Considerations

Costar's Experience Across Unit Counts