The rule changes by municipality
Start with the city where the property is located.
Mississauga, OntarioYes. Mississauga lists skylights among projects that require a building permit.
Because a skylight can alter roof framing and the building envelope, the permit scope should document the opening and structural support.
Toronto, OntarioSome skylight installations do not require a building permit when Toronto's listed small-building and structural conditions are met.
Toronto lists skylight installation as permit-exempt when the existing building is a house or small building three storeys or less and the work does not require removal of more than one rafter, joist or similar structural member, except a truss.
Ontario sets the Building Code. Municipal rules, zoning, processes and project guidance still differ.
We publish a city only after attaching municipal sources to the project answer. Missing coverage stays missing instead of borrowing another city’s rule.