Protection for the family and occupants, For many years the Ontario Building Code has required smoke alarms on every level of your home and carbon monoxide alarms in sleeping areas. These are the minimal requirement to comply with Ontario law. The best option for safety reasons is to install interconnected combination smoke alarms and carbon monoxide alarms on every level of your house. Why every level? Because you want to know immediately when there is a danger from carbon monoxide, smoke or fire in your home. For example, if you and your family are sound asleep on the second floor.