An unfinished basement can quietly become a bedroom, office, or television room without anyone reconsidering the alarm plan. In 2026, there is another reason to check it: Ontario's carbon monoxide requirements expanded.
What changed for houses
Toronto Fire Services explains that homes with a fuel-burning appliance, fireplace, or attached garage need CO alarms adjacent to sleeping areas and, from January 1, 2026, on every storey. The basement counts even when nobody sleeps there.
Its guidance also identifies circumstances affecting apartments and condos, including units heated by air from a fuel-burning appliance outside the unit and certain relationships to garages or service rooms. Check the arrangement of the actual dwelling; an electric appliance inside the suite does not settle the whole question.
Smoke and CO are separate checks
Ontario's home fire-safety guidance requires working smoke alarms on every storey and outside sleeping areas. A combination alarm may serve both purposes when suitable, but the model, location, installation, and applicable requirements still need to be correct.
Adding a basement bedroom can also change where the sleeping-area coverage belongs. Do not assume the old alarm beside the stairs covers the revised floor plan.
A new suite needs its approved alarm design
Ontario's second-unit guide describes additional smoke-alarm provisions for conversions. Have the designer confirm the current Building Code requirements, including bedroom locations, power supply, interconnection, and any applicable alteration provisions.
An existing-home minimum is not automatically the complete specification for newly permitted work. Put the alarm locations and system requirements on the drawings before electrical rough-in.
Make one deliberate check
- Identify which CO rules apply to the house or unit.
- Walk every storey and every sleeping area against the planned locations.
- Check the device type, expiry information, and manufacturer's installation instructions.
- Test alarms as directed and keep them operating during the renovation.
If a CO alarm sounds, move everyone outside and call 911 from a safe location. Do not investigate the furnace first.
An alarm plan is a small drawing with a serious purpose. Finish it before the room gets comfortable enough that nobody remembers it used to be unfinished.