A residential accessory building is a detached structure with a separate or secondary use to your house. It must be located on the same lot as your dwelling and cannot be used for commercial purposes or for habitation. Some examples of accessory buildings include garden sheds, gazebos, and garages.
Do I need a permit to construct a residential accessory building?
A Building Permit is required for the construction of detached structures that are greater than 10 square metres (108 square feet) in area. A Building Permit is required for structures 10 square metres or less, if they contain plumbing. Garages and carports attached to the principal dwelling, regardless of size, are considered to be additions and always require a Building Permit.
Note: Although a Building Permit may not be required for detached structures that are less than 10 square metres in area, all accessory buildings must meet Zoning By- Law requirements and other applicable provincial and municipal regulations.
Apply for a building permit
When building a residential accessory structure, you will need to submit:
- A completed Application to Construct or Demolish (PDF, 72 KB)
- A Site Plan must be included your permit application. A Site Plan identifies buildings and other features in relation to property boundaries. The Site Plan should show your existing house and the size and location of the proposed porch or deck. Ensure to include this information on your Site Plan:
- Title, scale, north arrow, and property dimensions
- Legal description including lot and plan number, street name and municipal address number
- Setbacks to all property lines for the existing dwelling and the proposed accessory building (including roof/eave overhang)
- Any right-of-ways and/or easements
- Location and size of all accessory buildings, porches, decks, or swimming pools
- Front yard landscaping, such as a driveway or sidewalks (if applicable)
- Location of existing septic system (if applicable)
- Detailed construction drawings, usually in the form of floor plans and elevations, including:
- Dimensions of proposed accessory building, including the height from grade to roof peak
- Slab, foundation wall, or pier construction details including size, depth, and compressive strength of concrete
- Width, location, and lintel size of all openings
- Size, spacing, and grade of studs and any structural members
- Roof framing: size, spacing, and grade of rafters, showing support details at all bearing points; or, if using trusses, the manufacturer’s engineered drawings (request these from your truss supplier)
- View a sample drawing (PDF, 63 KB)
Refer to the Accessory Structure Checklist (PDF, 489 KB) when preparing your application to ensure you have the required information.
For more detailed information about applying for a building permit, visit Building Permit Application Requirements.
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