Triplex and Fourplex in BC: Cost, Zoning, and Unit Count Rules (2026)

Triplex and fourplex at a glance

Both fall under BC Building Code Part 9. Both are permitted by right on most single-family lots under R1-1 zoning and SSMUH. The exact unit count a lot qualifies for depends on its specific SSMUH tier.

What changed under Bill 44 and SSMUH

Before BC's 2023 housing legislation, building a triplex or fourplex on a Vancouver single-family lot usually needed a rezoning application, a discretionary and slower process. Bill 44 introduced Small-Scale Multi-Unit Housing (SSMUH) rules that require any municipality with a population over 5,000 to permit three to four units on a lot previously zoned for one house.

Vancouver implements this through R1-1 zoning. In practice, this means:

• Three to four units is now a permitted use by right on most qualifying lots, not a special approval.
• The exact unit count (three or four) depends on the lot's specific SSMUH tier, set by lot area and frontage.
• Projects still go through development permit and building permit review, but skip the discretionary rezoning step in most cases.

Building code classification

Both a triplex and a fourplex qualify as Part 9 residential buildings under the BC Building Code, the same prescriptive path used for single-family homes and duplexes, capped at three storeys and 600 square metres per unit. This keeps construction methods, inspection requirements, and permitting complexity close to a standard house build, rather than the commercial-grade Part 3 path that applies at a higher unit or height threshold.

The Part 9 classification is why triplex and fourplex construction costs scale roughly with square footage and unit count, rather than jumping to a different cost structure the way a true apartment building would.

Cost comparison

See the dedicated triplex cost and zoning guide and fourplex cost and zoning guide for the full line-item breakdown of each.

Financing both building types

CMHC insures owner-occupied buildings of one to four units, covering both a triplex and a fourplex, with the same down payment tiers: 5% on the first $500,000 of purchase price, 10% on the portion from $500,001 to $999,999, and 20% at or above $1 million. CMHC-insured financing is not available above a $999,999 purchase price, which puts most Metro Vancouver triplexes and fourplexes into the 20%-down category in practice.

The financing rules change sharply only once a fifth unit is added: at 5+ units, a project falls under CMHC MLI Select, a purpose-built rental program with its own points system and no owner-occupancy requirement. See the full CMHC multiplex financing guide for both programs side by side.

Choosing between the two

The right unit count depends on what a specific lot supports and how much rental-income risk an owner wants to carry:

1. Check lot size and frontage. A standard 33-foot by 122-foot lot typically supports a fourplex; smaller lots may cap out at a triplex.
2. Compare vacancy risk. A fourplex loses 25% of rental income if one unit sits empty; a triplex loses 33%.
3. Compare total budget. A fourplex costs more in total but typically less per unit.
4. Confirm financing fit. Both qualify under the same CMHC 1-to-4-unit rules if purchase price allows.

See the full duplex vs triplex vs fourplex comparison for a side-by-side table including the duplex option.

Frequently asked questions