Do I need a special permit to renovate a heritage-designated property in Ontario?

Yes, generally. Alterations affecting the heritage attributes identified in a property's designating bylaw typically require municipal approval before the work begins, separate from any ordinary building permit that would otherwise apply to the same renovation. This approval process is meant to let the municipality confirm the proposed changes are compatible with the property's protected heritage character before work starts, rather than reviewing it after the fact.

Not every renovation on a designated property necessarily needs this heritage-specific approval; the trigger is generally whether the work affects the attributes actually identified in the designating bylaw, which is why reviewing that bylaw closely matters before assuming any particular project does or doesn't need approval. Interior work that doesn't touch protected exterior or structural heritage features may fall outside the heritage approval requirement even though a building permit is still needed for the construction itself. Because doing unauthorized work on a protected attribute can lead to enforcement action and a requirement to restore the property, owners planning any renovation to a designated property should confirm with the municipality's heritage planning staff early, before finalizing design plans or a contractor's schedule.