Learn about Additional Residential Units (ARUs)

Learn how to add an Additional Residential Unit (ARU) to your property.

On this page:

  1. What are ARUs?
  2. Check if ARUs are allowed on your property
  3. Get required permits and licences
  4. Learn how to add an ARU
  5. Apply for the ARU grant
  6. Find more resources
  7. Contact us

What are ARUs?

Additional Residential Units (ARUs) are separate, self-contained living spaces within a home or on the same property. They help add more homes while using existing roads, utilities and services.

Each ARU has its own kitchen, bathroom and living area. You can use an ARU for family members or rent it out for extra income.

ARUs can be:

  • inside a single-detached, semi-detached or townhouse building
  • in a backyard coach house or other detached structure

Check if ARUs are allowed on your property

Check your property’s zoning before you start planning an ARU. 

The city’s updated zoning bylaw allows:

  • up to 4 units on a low-rise residential property
  • buildings up to 4 storeys in all low-rise residential areas

For detailed zoning information, check Zoning Bylaw 2018-050, especially:

  • section 3.A.1B Additional Residential Units
  • section 3.C.2 Coach houses

Get required permits and licences

Before construction starts, make sure you have:

  1. Building permit – apply through our building permits page
  2. Rental licence – required if you plan to rent out the unit; apply through our rental licences page

How to add an ARU

Use our Additional Residential Unit toolkit to learn how to:

  • add Additional Rental Units: convert spaces, build coach houses or expand homes
  • get permits: follow zoning rules, apply for permits and meet building codes
  • plan costs: budget for fees, access incentives and generate rental income

Download Additional Residential Unit toolkit (PDF)

Apply for the ARU grant

You may qualify for the ARU grant. You can get up to $30,000 to build an additional residential unit if it will be rented at an affordable rate.

Learn more and apply for the ARU grant.

Find more ARU resources

Check out Ontario's Second Unit Guide, a detailed online resource on building an ARUs, including regulations and requirements.

CMHC's Housing Design Catalogue includes sample designs for ARUs and fourplexes.

Contact us

Email ARU@waterloo.ca if you have questions or need help with your project.