Additional Dwelling Units

Single Unit and Duplex Unit Dwellings

For a single detached and duplex dwelling, the main building may contain a maximum of three (3) dwelling units with zero (0) dwelling units in the accessory building or a maximum of two (2) units in the main building and one (1) dwelling unit in the accessory building.

Semi-Detached Dwellings

For a semi-detached dwelling, the main building may contain a maximum of three (3) dwelling units with zero (0) dwelling units in the accessory building per semi or a maximum of two (2) units in the main building and one (1) dwelling unit in the accessory building per semi.

The informative video below provides an overview of Additional Dwelling Units as the permitting process to legally establish these units:

Benefits of Additional Dwelling Units

• Support changing demographics by providing more housing options for extended families or elderly parents, or for a live-in caregiver,
• Allow extended families and live-in caregivers to live together but independently,
• Allow seniors to remain in their homes as they age,
• Make more efficient use of existing infrastructure, including public transit where it exists or is planned,
• Make more efficient use of the existing housing stock,
• Assist municipalities in meeting their goals regarding affordable housing, intensification and density targets, and climate change mitigation.
• Provide an increase in available housing/rental units,
• Provide opportunities for homeowners to earn additional income to help meet the cost of homeownership,
• Provide housing diversity to meet needs of a varied family sizes,
• Enable gentle densification of existing neighbourhoods without affecting the neighbourhood character, and
• Help create mixed-income and inclusionary communities, which support local businesses and local labour markets.

Where are Additional Dwelling Units (ADUs) Permitted?

1. ADUs are permitted in residential areas within single detached, semi-detached, duplex, and townhome/rowhouse dwellings and/or within a building accessory to these dwelling types. ADUs are not permitted within any other dwelling type (e.g. a double duplex or multiple dwelling). To confirm whether an ADU is permitted, please contact the Planning Division by referring to the contact information provided below.
2. In floodplain areas, ADUs are not permitted within basements. See map of areas regulated by the Essex Region Conservation Authority (ERCA). For more information regarding the location of floodplain areas, please contact ERCA at 519-776-5209 or admin@erca.org.
3. Outside of floodplain areas, basement units may be permitted where downspouts have been disconnected, a sump pump has been installed, and a backflow prevention valve has been installed. Click the following links for more information regarding:
   • Downspout (eaves trough) disconnection
   • Backflow prevention
   • Basement Flooding Protection Subsidy Program

One additional parking space must be provided for an ADU, except for properties located within older core areas of the city that have smaller lots sizes and are well served by transit. See map of the area where an additional parking space is not required. If a second ADU is added to a lot, no additional parking space is required for that unit.

Heritage Properties

Properties listed on the Municipal Heritage Register or located within a heritage area cannot alter any part of the exterior of the dwelling that is visible from the street for the purposes of adding an ADU. Please contact the Heritage Planner at 519-255-6543 ext. 6179 or email planningdept@citywindsor.ca if you have questions about the Municipal Heritage Register.

Accessory Buildings

Additional Dwelling Units located within accessory buildings (detached ADUs):

• Must have access to a paved public street, municipal sanitary sewer, municipal storm water outlet, electrical and water services;
• Must have direct pedestrian access from the street or alley (i.e. tenants must not be required to access the second unit through the primary unit);
• Must have a municipal address clearly visible from the street; and
• Cannot be severed from the property containing the primary dwelling unit.
• Must have minimum side and rear setbacks of 1.2 metres. If upgrading or adding to an existing garage to include an ADU, the 1.2 metre setback only applies to the portion of the building that is being altered.
• For a detached ADU, must adhere to maximum height restrictions dependent on the roof slope:
• • For roofs with a slope of 20 degrees (approximately 4/12 roof pitch) or more the maximum height is 8 metres (26 feet).
  • For roofs with a slope of less than 20 degrees, the maximum height is 6 metres. The maximum height for low slope or flat roofs may be increased to 8 metres (26 feet) through minor variance. See information about applying for a minor variance.

• For a detached ADU, must not have a maximum height exceeding the building height of the main building on the lot. For example, a two-storey ADU is not permitted on a lot where the main building is only a single storey.

Please see Section 5.99.80 of Zoning By-law 8600 for detailed requirements. For questions related to ADU policies and zoning regulations contact:

Building Permit Required

Each building can have a different set of circumstances that may affect the design of an Additional Dwelling Unit. Part 9 of the Ontario Building Code (OBC) applies to the design and creation of ADUs. Specifically, the sections of the OBC listed below must be addressed while designing a proposed ADU:

• 9.4 – Structural Requirements
• 9.5 – Design of Area, Spaces and Doorways
• 9.7 – Windows, Doors and Skylights
• 9.8 – Stairs Ramps, Handrails and Guards
• 9.9 – Means of Egress
• 9.10 – Fire Protection
• 9.11 – Excavation
• 9.31 – Plumbing Facilities
• 9.32 – Ventilation
• 9.33 – Heating and Air-Conditioning

For questions relating to submitting a building permit application contact: