Additional Residential Units Guide: Legalizing Existing Unit

SERVICE ANNOUNCEMENT: Bill 23 and Additional Residential Units
New Regulations for Additional Residential Units

Please note that the City’s requirements for Additional Residential Units (previously known as Secondary Suites) have changed effective August 28, 2023 pursuant to By-law 23-087

Bill 23, More Homes Built Faster Act, 2022 was introduced by the Province on October 25, 2022. Third reading and Royal Assent was granted on November 28, 2022. The new legislation makes amendments to nine different statutes, including the Conservation Authorities Act, the Municipal Act, 2001, the Ontario Heritage Act, the Ontario Land Tribunal Act, 2021, and the Planning Act. The associated regulations relating to additional residential units came into force on December 23, 2022.

With the intention of increasing the supply of housing, the Province introduced changes to the Planning Act to allow gentle density/intensification by requiring municipal zoning to permit ‘gentle intensification’ of up to 3 units per lot (up to two in the main building and one in an accessory building or up to three in the main building) in a detached, semi-detached or townhouse dwelling; prohibiting municipal zoning to regulate minimum unit size or from requiring more than one parking space per unit for ‘gentle intensification’ units; and exempting ‘gentle intensification’ units from Development Charges, Parkland and Community Benefit contributions.

Printable version of the New Additional Residential Units Guide

A printable copy of the New Additional Residential Units (ARUs) Guide is available online in an Adobe PDF format.

Recognizing an apartment that existed as of November 16, 1995

ARUs that existed as of November 16, 1995 may be exempt from having to comply with the City’s Zoning By-law regulations related to ARUs in accordance with Ontario Regulation 384/94 (Apartments in Houses)

  1. To qualify, the ARU must have existed on November 16, 1995
  2. Be located within Principal Dwelling that is:
    • a single detached dwelling
    • a semi-detached dwelling that was not created by the alteration of a single detached dwelling
    • a row/townhouse dwelling that was not created by the alteration of a single detached or semi-detached dwelling
  3. As of November 16, 1995, the dwelling must have:
    • been used for, or was intended to be used for, residential purposes
    • contained no more than one ARU
    • not been ancillary to any other dwelling or use
    • been located in a zone that permits residential use as a primary use
    • been serviced with municipal water and sanitary sewers
  4. Property Owner must provide the following to the Building Division
    • a declaration sworn in front of a Commissioner of Oaths (or a lawyer) by a person with personal knowledge of the property declaring that the house was used or occupied as two residential units on November 16, 1995
      • Person could be the current owner, a previous owner, a relative of an owner, neighbour, tenant, realtor, etc.
    • printed documentation establishing the ARU’s existence as of November 16, 1995
      • Examples: rent receipts, income tax records, service records from contractors/utilities, etc
    • Documentation of successful Fire Code Compliance inspection and Ontario Electrical Safety Authority inspection
    • Applicable ARU processing fee

Legalizing an Existing Unit Built after November 16, 1995

  1. Lot and unit must comply with the Zoning By-law requirements.
  2. A building permit must be obtained to recognize the existing construction.
  3. The ARU must pass all required inspections associated with the building permit.
  4. Detailed requirements are outlined on our "ARU Guide - Building A New ARU"


 What if my existing ARU does not meet the Zoning By-law regulations?
One of the following may be required: 
  • Alterations to the ARU or property layout (e.g. removing a bedroom, expanding a driveway) to bring the ARU or property into compliance with the ARU regulations;
  • An application to rezone the property to allow for more than one Principal Dwelling such as a duplex or a semi-detached dwelling; or,
  • Renovating the dwelling to incorporate the living space associated with the ARU into the Principal Dwelling, thereby removing the ARU.
What if my existing ARU does not meet Building Code or Electrical Safety Code regulations?

The ARU cannot be legalized if it does not meet applicable law such as the Building Code and the Electrical Safety Code

Renovations may be required to bring the ARU into compliance with the Building Code

Code compliance will be addressed through the process to obtain and complete a building permit

What if my property cannot meet the minimum parking requirements?
If additional parking cannot be provided on the property, the ARU may need to be removed or the property may need to be re-zoned

What if I am unable to prove that my ARU met the criteria listed as of November 16, 1995?

  • You may be eligible to legalize the ARU under City’s ARU regulations
  • The lot and ARU would need to comply with Zoning By-law requirements
  • A building permit would be required to recognize the existing ARU
  • The ARU would need to pass all required inspections associated with the building permit
My house was legally constructed with an ARU, but the Zoning By-law no longer permits an ARU on my property
  • The ARU may be considered a “legal non-conforming use” if it was legally constructed in accordance with the applicable Zoning By-law in effect at the time and the Zoning By-law was subsequently changed to prohibit the use
  • To be considered a legal non-conforming use, the Owner must be able to demonstrate that the ARU was once a permitted use and that the ARU has continuously been used that way since the Zoning By-law changed
  • A legal non-conforming use may continue to exist despite the Zoning By-law change as long as it continues to be used for the purpose that lawfully existed prior to the Zoning By-law change

Disclaimer: The design examples, including sample drawings, in this guide are not advice nor do they address all the requirements for legally establishing an ARU. It is each property owner’s responsibility to ensure compliance with all current applicable law, including the Ontario Building Code, the City’s Comprehensive Zoning By-law and any other provisions or regulations applicable to ARUs. A copy of the Ontario Building Code (Ontario Regulation 332/12 made under the Building Code Act, 1992) is available online through the e-Laws website.