Mississauga fourplex rules: what you can build in 2026

Mississauga is one of the GTA’s most multiplex-friendly cities. In December 2023 City Council approved Official Plan and zoning changes that permit fourplexes on low-rise residential lots across the city, and the City confirms those permissions are in effect. Here is what that means in practice.

What Mississauga permits

• Fourplexes (four residential units) are permitted as-of-right on low-rise residential lots citywide.
• “As-of-right” means you can apply for a building permit without additional zoning approvals, if your plans meet the by-law regulations.
• Fourplexes can be up to three storeys, including a partially above-grade basement unit.
• You can build a purpose-built fourplex or convert an existing property to four units, and a range of layouts is supported.

Additional units: garden suites, laneway suites and more

Separately from fourplexes, Mississauga’s additional-unit rules allow up to three residential units on one lot, including the primary residence. That covers garden suites, garage conversions, triplexes and laneway suites. One- and two-storey additional units are subject to lot-size and height parameters set out in the zoning.

What still decides whether your lot works

As-of-right does not mean any lot, any design. Your lot still has to meet the by-law’s requirements, and the City’s news release does not list every standard. Frontage and depth, setbacks, height, parking, servicing, trees and the specific zone all affect how many good units fit. Rules are also amended over time, so confirm the current by-law for your address.

How to check your Mississauga lot

Start with the City’s zoning for your address, then work through the standards that shape the building. A feasibility review does this for you: it tells you how many units your lot can realistically hold, what it costs to build, and the rental cashflow you could expect.