For a basement apartment to be legal in Ontario, it needs to meet the building code requirements. Firstly, your building needs to be more than five years old and meet the zoning codes specific to your area. The basement apartment needs to have a minimum of 145 square feet and a ceiling height of 1.95 meters. The space should have laundry, kitchen, sink, heating, and cooling. The apartment needs to meet the Fire Code, specific for your municipality, so be sure to check with the authorities for accurate information.