You will need to find out if the property is older than sixty years. Section 34 of the National Heritage Resources Act states that "No person may alter or demolish any structure or part of a structure which is older than 60 years without a permit issued by the relevant provincial heritage resources authority."
See here for advice on how to find out if your property is older than sixty.If the property is older than 60 years contact the relevant heritage authority for details about the application process.
Contact details can be found here