The short answer
If your project changes the structure, adds space, adds a unit, changes how a building is used, or alters plumbing or heating systems, you almost certainly need a building permit. Cosmetic work usually does not. Your municipality makes the final call, so always confirm with its building department before work starts.
Projects that usually need a permit
- Additions of any kind: rear additions, second storeys, attached garages, sunrooms, porches and most decks
- Structural changes: removing or adding walls, especially load-bearing walls, and adding, enlarging or moving windows and doors
- Creating a basement apartment, garden suite or any other additional unit
- Basement finishes that involve structural changes, new plumbing or heating, excavation, underpinning or a new entrance
- Installing or changing plumbing or heating systems, including backwater valves
- Installing or rebuilding a chimney or fireplace, or adding a wood-burning stove
- Decks more than 60 cm (about 2 ft) above the ground
- Demolishing all or part of a building
- Changing the use of a building or space, even with no construction, such as converting a retail unit into a clinic
- Most commercial fit-outs and tenant improvements
Projects that usually don’t
- Painting, flooring, cabinetry, countertops and other finishes
- Replacing a window or door in an existing opening of a house, with no change to its size or structure
- Replacing roofing without structural work
- Replacing a furnace or water heater in a house, or repairing or replacing plumbing fixtures
- Finishing a basement with no structural, plumbing or heating changes and no new unit
- Small sheds under 15 m² that are one storey, detached, used only for storage and have no plumbing
Even when no permit is needed, zoning rules such as setbacks and lot coverage still apply.
Who issues permits here
- Hamilton, including Stoney Creek, Ancaster, Dundas, Waterdown, Flamborough and Glanbrook: the City of Hamilton
- Burlington: the City of Burlington
- Oakville: the Town of Oakville
Properties near the Niagara Escarpment, creeks or valley lands may also need approval from a conservation authority or the Niagara Escarpment Commission. Designated heritage properties may need a heritage permit.
What a permit application usually involves
- Check zoning. Confirm the project fits the zoning by-law for setbacks, height, lot coverage and use. If it doesn’t, a minor variance or other approval may be needed first.
- Prepare drawings. Site plan, floor plans, elevations and sections, plus structural design where beams, foundations or framing change.
- Submit and respond. The municipality reviews the application and may ask for changes or more information.
- Build and inspect. Inspections happen at set stages, such as footings, framing, insulation and final.
Why it matters
Unpermitted work can mean stop-work orders, having to open finished walls for inspection, insurance problems and trouble when you sell. A permit also gives you an independent check that structural and life-safety work meets the Building Code.
How we help
We prepare drawings and structural design and support the permit submission, then build to the approved plans. Approval timing and decisions rest with the municipality. See our engineering and permit consultation service.
This guide is general information based on the Ontario Building Code and municipal guidance. It is not legal advice. Requirements change, so confirm your project with your municipality.