Additional Residential Units

An Additional Residential Unit (ARU) is a self-contained residential dwelling unit, with its own kitchen, washroom and sleeping area, that either forms part of and is attached to the principal dwelling, or is located within a detached building on the same lot as the principal dwelling. 

In Cambridge, any individual lot containing a single detached house, semi-detached house or townhouse may contain up to two additional residential units, for a total of three units, in either of the following configurations: 

  • Up to 2 units within the main residential building, and 1 additional unit within a detached accessory structure; or
  • Up to 3 units within the main residential building.   

Additional Residential Units can be created through: 

  • the conversion of existing space within the main residential building
  • an addition to the main residential building
  • the conversion of an existing accessory structure on the lot
  • the addition of a new accessory structure on the lot

ARUs are required to be constructed with a building permit in accordance with the Ontario Building Code. Occupancy of the unit must be approved by the City of Cambridge Building Services Division. Additional Residential Units must comply with the the regulations in Section 4.19 of the City's Zoning By-law 26-007, including setbacks, parking, access to and location of entrances. The City and Region do not collect development charges for ARUs. The School Boards (WRDSB and WCDSB) do collect development charges under certain circumstances. For more information, contact the School Boards at edc@wrdsb.ca and edc@wcdsb.ca.

For more information on the permit application process or Ontario Building Code for ARUs, email building@cambridge.ca. For more information on ARU By-law 23-077, email planning@cambridge.ca. 

Background Information:

Financial Assistance Program

As of November 1, 2024, the City will be accepting applications from property owners who have constructed an Additional Residential Unit to qualify for a one time grant of up to $10,000. The grant is offered to compensate for costs related to: 

  • Upgrading of sanitary and/or water services;   
  • Professionally prepared permit drawings; and 
  • Hard construction costs (labour and materials).   

Follow the step-by-step instructions below to apply: 

  1. Visit our online portal. Create an account or login with your existing account. 
  2. Click "Financial Incentives" on the side menu.  
  3. Select "New Application" from the options that appear. 
  4. On the main screen, select “Additional Residential Unit Community Improvement Plan”
  5. Follow the prompts to fill out and submit your application

Please be advised that as part of the application process, the following supporting documents will be required: 

  1. A parcel register as proof of property ownership
  2. Invoices indicating a breakdown of costs such as: 
    • Professionally prepared drawings
    • Upsizing sanitary and water pipes
    • Labour and building material costs

For a copy of the Additional Residential Unit Financial Assistance program document, which includes a detailed description of the program, submission requirements and grant qualifications, please submit a request to planning@cambridge.ca. 

After reviewing an application, the City will advise whether the applicant has (or has not) been awarded a grant, or additional information is required.  

If you have questions about the program, or the status of your application, please contact Ann Godly, godlya@cambridge.ca or for general inquiries contact planning@cambridge.ca 

Apply to the ARU Financial Assistance Program