If you own a detached, semi-detached or town home, you can build a fourplex on your property, depending on the size of your lot.

A fourplex with four separate unitsA fourplex is a single low‑rise residential building containing four separate units. Each unit is a self‑contained suite that has cooking, living, sleeping and washroom facilities.

Different regulations apply based on whether the fourplex is a new build or a conversion of the existing home. There are also Ontario Building Code requirements which may have implications on the design of the building.

Fourplex conversions are low-rise residential buildings that have been remodelled to accommodate four separate units. In this case, all four units must fit within the building footprint of the home that existed as of December 6, 2023. Additions can’t be built to accommodate four units. For more information, review the fourplex by law.
A purpose-built fourplex is a new residential building that’s designed and built to accommodate four separate units. These fourplexes are subject to new zoning regulations, which provide more flexibility than conversions. That includes additional height, reduced setbacks and increased lot coverage. For more information, review the fourplex by law.

Submitting your permit application

You need a building permit to build a fourplex on your property. The City requires drawings of your proposal so we can determine if what you’re building is safe and complies with the Zoning By‑law, the Ontario Building Code and any other applicable law. Work with a qualified designer to make sure your project meets regulations.

For detailed application requirements, refer to the drawings and documents for a building permit.

Once your permit application is submitted, we will provide information on next steps.

Permit fees and charges

Total permit fees depend on the size and type of units you’re building. They will be calculated once we pre-screen your request. To find out how much your building permit may cost, refer to the fee schedule.

Fourplexes are also subject to development charges and cash‑in‑lieu of parkland, which must be paid before we can issue your permit.

Permit processing times

If your application is complete, the first review may take 15 business days. Applications that must be resubmitted may result in delays of two weeks or more. For more information, refer to the times for processing and issuing a permit.

Contact us

If you have questions about building more units, call 311 (905-615-4311 outside City limits).