What Drawings Are Required for a Building Permit?

A site plan shows the property from above: lot lines, existing buildings, the location of the proposed work, setbacks from property lines, and often driveways, utilities, and grading. Municipalities use the site plan to confirm that a project complies with local zoning rules, including how close a structure can sit to a lot line and how much of the lot can be covered by buildings.

Site plans are typically required for any project that changes a building's footprint, such as additions, new garages, sheds over a certain size, decks, and new construction. Interior-only renovations that don't change the building's footprint sometimes don't need a full site plan, but many municipalities still ask for one to confirm the address and property details.

Floor plans are usually required in two versions: the existing layout of the space and the proposed layout after the work is complete. This lets the reviewer see exactly what is changing — new walls, removed walls, relocated plumbing fixtures, new bedrooms, and changes to room use.

Floor plans need to show dimensions, room labels, window and door locations and sizes, and details like smoke and carbon monoxide alarm locations. For basement projects specifically, floor plans typically need to show ceiling heights and egress window sizing, since these directly affect whether a room can be used as a bedroom.

Elevation drawings show the exterior faces of a building — front, rear, and sides — as they will look after construction. They are most commonly required for projects that change a building's exterior, such as additions, new garages, second-storey additions, and decks or porches.

Elevations help the municipality confirm details like overall building height, window and door placement on exterior walls, and how the new work will relate to the existing structure and to neighbouring properties.

Any project that involves structural change — removing or altering a load-bearing wall, adding a second storey, building a deck, or constructing a new addition — typically requires structural drawings or details. These can range from standard construction details for a straightforward deck to fully engineered drawings and calculations for larger structural changes.

Structural documentation is one of the areas where scope matters most. A small, code-compliant deck might only need standard construction details, while a load-bearing wall removal or a new second storey usually needs drawings and calculations prepared or reviewed by a qualified structural engineer.

Not every project needs every drawing type. A simple basement bathroom rough-in might only need a basic floor plan and plumbing layout, while a duplex conversion or a full second-storey addition will typically require the complete set: site plan, existing and proposed floor plans, elevations, and structural drawings. The building department reviewing your application will tell you exactly which drawings your specific project needs.

As a general rule, the more a project changes a building's structure, footprint, exits, or occupancy, the more complete the drawing package needs to be.

In Ontario, most building permit drawings need to be prepared by a designer registered with the Building Code Identification Number (BCIN) program, or by an architect or engineer, depending on the project's size and category. You can learn more about the provincial requirements for becoming a registered building practitioner at https://www.ontario.ca/page/become-registered-building-practitioner, and verify a designer's registration status through the public QuARTS registry at https://www.search.quarts.mah.gov.on.ca/en/.

Working with a registered designer helps ensure your drawings meet the Ontario Building Code and are prepared in the format your municipality expects, which generally reduces the back-and-forth during plan review.