Does your renovation need a building permit in Ontario?
In Ontario you need a building permit before renovations, additions and most new buildings over 10 m2. Some small sheds are exempt. What to check with your municipality first.
Work done without a permit tends to surface at the worst time: when you sell, refinance or make an insurance claim. In Ontario, the building permit is issued by your municipality under the provincial Building Code.
The general rule
The Government of Ontario's citizens' guide says you must get a building permit before you construct any new building over 10 square metres in area, and before renovations or additions. The guide describes this as a general rule; your municipal building department applies the details.
Small sheds
The Building Code exempts some sheds from the permit requirement and from Code compliance when they are not more than 15 square metres in gross area, subject to conditions. Confirm the conditions with your municipality before you build.
Decks and other small projects
There is no general deck exemption in the provincial guide. Ask your building department about decks, porches, basement finishing, removing walls and changing plumbing or heating; many of these need permits.
Zoning and other approvals come first
If your project needs a zoning change or a minor variance, a building permit will not be issued until you have it. Heritage properties may need separate approval, and properties near water or other natural hazards may need a conservation authority permit.
Other permits on the same job
Electrical work needs a separate ESA notification, and gas work must be done by a TSSA-registered contractor. A building permit does not cover those.
Prevention Checklist
- Call or check your municipal building department before you design.
- Assume renovations and additions need a permit unless told otherwise.
- Check sheds against the 15 m2 exemption conditions.
- Get zoning, heritage or conservation approvals first if needed.
- Add the ESA notification and TSSA contractor for electrical and gas work.
References
- Government of Ontario. Citizens' guide to land use planning: Building permits, Web page, General rule; zoning before permit. Accessed 2026-11-01.
- Government of Ontario. 2024 Building Code Compendium, Part 1 - General, Web page, Shed exemption. Accessed 2026-11-01.
- Government of Ontario. Your rights when starting home renovations or repairs, Web page, Consumer guidance. Accessed 2026-11-01.
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General information based on the official sources listed above, not legal, tax or engineering advice. Rules change; check the source or ask a qualified professional before you act.
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