Accessory Apartments

How do I know if I can add an accessory apartment?

The property must comply with the regulations for that zone. 

See the regulation chart for the property’s zoning in Zoning By-law 60-94, as amended (e.g. If the property is zoned R1-C, you must provide 13.5m of frontage per the Zoning By-law).

The property must also comply with the below Zoning regulations:

• Minimum parking requirements (details below),
• Minimum Landscape Open Space requirements (50% landscape must be maintained in certain yards), and
• Comply with the regulations under Section 5.1 of the City of Oshawa Zoning By-law 60-94, as amended

 How do I determine what my property is zoned?

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 60-94 to determine what uses are permitted and what regulations apply.

 How many parking spaces are required?

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 [email protected] regarding Access Permits for city streets and contact the Regional Municipality of Durham at www.durham.ca for curb cuts for regional roads.

What zoning requirements must I consider to add a residential unit to a detached building?

(e.g. garden suite, tiny house, laneway house)

To build or add a residential unit within a detached building (accessory building) you must comply with our Zoning regulations pertaining to accessory buildings (see Section 5.1 of the City of Oshawa Zoning By-law 60-94, as amended). 

Lot Coverage: For most lots, the limitations for accessory buildings on a residential lot are the most restrictive of the following calculations:

• Maximum 8% of the total lot area or,

• Maximum 50% of the lot coverage of the house on the lot or,

• Maximum 60 m2 of ground floor area

Therefore, maximum size is whichever of the above is less.

Setbacks: In most cases, the minimum required setback is 2 ft.

Building Height: In most cases, the maximum height to the roof peak from grade is 14 ft 9 in. 

Location on property: In most cases, the accessory building cannot be in any part of the front yard, or the minimum required exterior side yard of a corner lot.

What if my property does not meet the zoning criteria to add an accessory apartment?

If your property has a legal non-complying frontage (e.g. the frontage is less than what the City of Oshawa Zoning By-law requires for the zone in which your property is in), or is not connected to municipal water and sanitary sewer but has minimum 11m frontage, you may be able to add one (1) accessory apartment within your single detached or semi-detached dwelling (not in an accessory building) per section 5.12 of City of Oshawa Zoning By-law 60-94, as amended, if all other zoning regulations comply.  

What design requirements or building code items need to be met to add 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.

 What else can affect adding an accessory apartment to my house?

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. 

How do I apply for a building permit to add an accessory apartment?

A building permit is required to construct or legalize an accessory apartment. Email your Building Permit Application to Building Permit and Inspection Services.

Please allow two business days after sending in a permit application to receive a response from our staff on acceptance and how to contact us for payment. 

Do I need to register my new accessory apartment?

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.