What does it mean if my Ontario property is designated under the Ontario Heritage Act?

Designation under the Ontario Heritage Act means a municipality has formally recognized your property as having cultural heritage value or interest, based on its architectural, historical, or contextual significance, and has passed a bylaw identifying the specific heritage attributes it wants protected. Once designated, those protected attributes, which might include the building's exterior, particular architectural features, or sometimes elements of the surrounding landscape, generally cannot be altered, added to, or removed without municipal approval first.

Designation doesn't freeze the property entirely or prevent all use or renovation; it means changes affecting the identified heritage attributes go through an approval process before work begins, rather than being left entirely to the owner's discretion the way they would be on a non-designated property. It also generally means the property can't be demolished without following a specific heritage-related process, which can take longer and involve more scrutiny than an ordinary demolition. If you're buying a designated property, or your own property has just been designated, it's worth getting a clear picture of exactly which attributes were identified in the designating bylaw, since that document defines what actually needs approval going forward and what remains entirely up to you.