Accessory Apartments

Accessory apartments (up to 2) are permitted within any single detached dwelling, semi-detached dwelling, semi-detached building, duplex or street townhouse dwelling or within an accessory building (residential only) located in a R1-A, R1-B, R1-C, R1-D, R1-E, R2, R3 or R5 Zone. Subject to meeting the below regulations.

• The lot is serviced by Municipal Water and Sewer
• The accessory apartment is not located within Hazards lands as identified by Central Lakes of Ontario Conservation Authority (CLOCA)
• The exterior entrance to an accessory apartment has a 0.81 m clear access route to the street line.
• Minimum parking requirements
• Minimum Landscape Open Space requirements (50% landscape must be maintained in certain yards)
• A maximum of 1 accessory unit may be in an accessory building on the property
• Accessory units within an accessory building must comply with the regulations under Section 5.1 of the City of Oshawa Zoning By-law, as amended.

If your property does not comply with the regulations as stated above 1 accessory unit shall be permitted within any single detached dwelling or semi-detached dwelling located in a R1, R2, R5, OSR-A, OS-ORM, AG-A, AG-B or AG-ORM Zone, subject to the following:

• The accessory apartment is not located within Hazards lands as identified by Central Lakes of Ontario Conservation Authority (CLOCA)
• A minimum lot frontage of 11 m shall be provided
• A lot containing 2 or more single detached dwellings or semidetached dwellings, or any of each in combination, may not have an accessory apartment.
• The accessory unit is located within the main dwelling, and not an accessory building

Note, in either case above, where an accessory apartment is located within a single detached dwelling, semi-detached dwelling or street townhouse dwelling, each dwelling unit on the lot within the main building shall have at least seventy-five percent (75%) of its floor area located wholly above or below another dwelling unit on the lot within the main building.

To determine the zoning of your property, please use our mapOshawa application on our interactive maps webpage. Once you have the zoning (e.g. R1-A) use Zoning By-law to determine what uses are permitted and what regulations apply.

One additional parking space is required for each accessory dwelling, in addition to the minimum parking requirements (2 spaces) for the existing single detached dwelling, semi-detached dwelling or townhouse. 

For a property containing two dwelling units;

• Three parking spaces are required, each space is 2.75m x 5.75m
• At least One space must be located within a side yard, rear yard, or garage
• Two spaces must have unobstructed street access (not parked in tandem)
• Minimum 50% front yard and 50% of the exterior side yard must be maintained as landscape open space
• Minimum 50% of the rear yard of a corner lot must be maintained as landscaped open space

 For a property containing three dwelling units;

• Four parking spaces are required, each space 2.75m x 5.75m
• One space must be located within a side yard, rear yard or in a garage
• Three spaces must have direct street access (not parked in tandem)
• Minimum 50% front yard and 50% of the exterior side yard must be maintained as landscape open space
• Minimum 50% of the rear yard of a corner lot must be maintained as landscaped open space

The parking spaces, which must be directly accessible to the street, often require the curb to be cut. This must be approved by the City of Oshawa (city street) or the Regional Municipality of Durham (regional road).  Please contact service@oshawa.ca regarding Access Permits for city streets and contact the Regional Municipality of Durham at Durham.ca for curb cuts for regional roads.

Note: The City of Oshawa monitors, regulates and enforces general parking regulations as outlined by the Transportation By-Laws. 

A maximum of one accessory unit may be located within an accessory building and is subject to the requirements applicable to accessory buildings (section 5.1) and accessory apartments (section 5.12) in the City of Oshawa Zoning By-law, as amended.

Those requirements include:

Lot Coverage: The most restrictive of the three calculations (listed below) determines the maximum permitted lot coverage for all accessory buildings on the lot combined:

• Maximum 8% of the total lot area or,
• Maximum 50% of the lot coverage of the house on the lot (Properties zoned R1-G and R1-H = 100%) or,
• Maximum 60 m2 of ground floor area (properties zoned R1-G and R1-H ground floor area is 90 m2).

Setbacks: The required distance from the proposed building to the property line.

• In most cases, the minimum required setback is 0.6 m or 2 ft

Building Height: Measured from grade to the highest peak of the building from the front elevation.

• Maximum permitted height 4.5 m or 14 ft 8 in 
• Maximum permitted height for properties zoned R1-G and R1-H is 5 m or 16 ft 4 in.

Location on property:

• A minimum distance of 3 m must be provided between the main dwelling and the accessory building dwelling,
• A clear pathway of 0.81 m (32 in) must be provided from the accessory building dwelling to the street line,
• A minimum setback of 30 m from any railway right of way, 14 m from any Highway (401/407) property line or 7 m from the outer limit of any gas or oil pipeline corridor.
• In most cases, accessory building dwellings cannot be located in the front yard

If your property does not meet the minimum zoning requirements, you may be interested in applying for a minor variance through the Committee of Adjustment (C of A.)

Our plans examination staff cannot give detailed specifics for requirements needed for individual properties to meet Ontario Building Code when adding an accessory apartment.

The Ministry of Municipal Affairs and Housing has prepared the following guides (as reference tools only):

• Adding a second unit in an existing house
• Build or buy a tiny home
• Building a laneway house

Community members should contact a qualified designer to assist with the required building permit drawings to ensure that the accessory apartment within the main building or within an accessory building complies with the Ontario Building Code requirements.

Your property may be located within Central Lake Ontario Conservation Authority (C.L.O.C.A.) regulated lands or within the Ministry of Transportation (M.T.O.) Highway Corridor controlled area. 

Please get in touch with these agencies to obtain a permit. 

 Learn more about building permit requirements and fees.

When you complete the building permit process to add an accessory apartment, your house will automatically be registered as a two-unit house. You will receive your certificate within 60 days of the building inspector closing your Building Permit. 

If you have an existing apartment in your house that is not registered (legalized) visit our two-unit houses webpage.