Accessory Structures

An accessory structure is a smaller building on a property—like a shed, a gazebo or a detached garage that supports the main building. The structure must comply the Ontario Building Code and the Zoning By‑law.

Getting started

You do not need a building permit for a shed that is only used for storage and is accessory to a principal building on the lot if it:

is not more than 15 m2 (161 sq. ft.) in gross area,
is not more than one storey in building height,
is not attached to a building or any other structure, and
does not contain any plumbing.

If your accessory building does not meet the criteria above, a building permit is required unless it:

is less than or equal to 10 m2 (107 sq. ft.) in gross area,
is not attached to a building or any other structure, and
does not contain any plumbing

Your accessory structure must comply with the Ontario Building Code and the City of Oshawa's Zoning By-Law even if a building permit is not required.

Your drawings must be to scale and use metric measurements to clearly show what exists and what is proposed. Additional information may be requested during the review process. See our digital permit standards which explain how to prepare your digital drawings and documentation files for the application.

Zoning requirements

In most cases, these are the zoning requirements for your shed/detached garage:

The maximum size is whichever of the following is smaller:

8% of the total lot area or,
50% of the lot coverage of the house on the lot or,
60 m2 of ground floor area

The minimum required distance from your property line is 2 ft.

The maximum height from the ground to the roof peak is 14 ft 9 in. For full zoning requirements see section 5.1 of the City of Oshawa's Zoning By-Law.

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.

Permit application requirements

For your project, you will need to submit:

Forms

Application to construct or demolish
Owner's authorization form will be required if you are not the property owner
Schedule 1 - designer information - located on page 3 of the permit application form

Site plan

The site plan must include the following:

Entire property with lot dimensions
The location, dimensions and setbacks to property lines of the proposed building/structure
The location and dimensions of all existing buildings (i.e. house, shed, garages) or structures (decks, porches) on the property
Setback of the proposed building / structure to any on-site sewage system components, or any easements, if applicable

Plan and section drawings

Foundation - please provide:
- Location, depth, size of footing or slab
- If structure is larger than 55m2, slab detail must be approved by a professional engineer
Framing - please provide:
- Floor, wall and roof construction details and framing of all openings (windows and doors)
- Interior and exterior dimensions, including door and window sizes
- Structural framing indicating the size, type, grade, spacing, direction of span and location of all structural members (joists, beams, posts and lintels, as well as engineered floor members when applicable)
- If pre-manufactured framing is used, sealed layout and specifications are required.
Elevations:
- All four directions including wall cladding and roof covering details
Cross section:
- Details of footings, foundation, walls, floors and the roof

If the foundation of your new shed or garage will be concrete, please visit our Oshawa Application Portal to apply for your site alteration permit. Please see our landscaping and grading website for additional information and submittal requirements.

Once the application as been accepted, the required permit fee will be payble through your portal account. Permit fees (see page 16) for different projects are provided in our Building By-law.

How to apply on portal for an accessory structure

From the drop-down menu please select detached garage/shed/gazebo as the application type.
In the description field please write a brief description of the type of structure that is being constructed.
Choose the appropriate work items that apply.
Enter the area (in square metres) of the structure.
Enter the address of the proposed structure.
Upload the PDF files of the required documents
Review and submit the application

Apply for an accessory structure permit on our application portal

Apply now

Resources

Building Permits

Shed and garage construction guide

Call before you dig

It is important you call Ontario One Call at 1-800-400-2255 before you dig to have them locate any underground utilities and avoid any damage during construction.