Ontario's Multiplex Zoning: What Bill 23 Means for Homeowners

Ontario's Bill 23, the More Homes Built Faster Act, quietly became one of the most significant pieces of housing legislation in the province's history when it received Royal Assent in late 2023. Among its many provisions, one stands out for homeowners and investors: as-of-right zoning for up to four residential units on most residential lots across Ontario.

What does "as-of-right" mean in practice? It means you no longer need a zoning variance, minor variance, or rezoning application to build a duplex, triplex, or fourplex on a residential lot. If your property meets the basic requirements — lot size, setbacks, height limits — you can proceed directly to site plan approval and building permits. This eliminates months of municipal hearings and tens of thousands of dollars in planning fees.

The impact on Toronto and the surrounding GTA has been substantial. Properties that were previously limited to a single detached home can now be redeveloped into multi-unit buildings that generate rental income, increase housing supply, and dramatically increase property value. A single-family home worth $1.2 million on a suitable lot could be replaced with a fourplex worth $3 million or more.

Not every lot qualifies equally. The legislation sets minimum lot sizes and maximum building envelopes that vary by municipality. In Toronto, lots need sufficient frontage and depth to accommodate the required parking (though some areas have reduced parking minimums), and the building must comply with the Ontario Building Code for multi-unit residential construction. A professional feasibility study is essential before committing to a project.

Financing a multiplex development is different from a standard home purchase. Most lenders offer construction financing based on the projected value of the completed building, not just the current land value. This means a well-designed project on a good lot can secure favorable financing terms. We work with clients and their lenders to provide the pro formas and construction schedules that banks require.

The construction timeline for a multiplex is longer than most homeowners expect. A typical duplex takes 14 to 18 months from initial design to occupancy. Triplexes and fourplexes can take 18 to 22 months. The design and permitting phase alone — including architectural drawings, engineering, and building permit review — typically takes three to four months.

One of the most common questions we hear is whether it makes financial sense to demolish an existing home to build a multiplex. The answer depends on the specific property, but the math often works strongly in favor of development. A lot with a teardown house might sell for $900,000, while a completed fourplex on the same lot could be worth $2.5 million or more, with annual rental income of $120,000 to $160,000.

At Metrohomes, we have been designing and building multiplexes across the GTA since the legislation took effect. Our design-build approach means a single team handles everything from initial feasibility analysis through construction to final occupancy — no coordination headaches between separate architects, engineers, and builders.

If you own a residential lot in Ontario and are curious about the multiplex potential, start with our free Property Assessment — it pulls real zoning data for your specific address in sixty seconds. For a deeper look at Bill 23, financing structures, and the rental math framework serious investors use, read our Multiplex Investor Guide. We also offer full feasibility consultations through our multiplex development service to review your lot dimensions, local zoning requirements, and financial goals in detail. For a comparison of duplex, triplex, and fourplex configurations, see which multiplex type fits your lot.