Smoke detectors are one of the simplest and most important safety devices in an Ontario home. They give your family early warning in the event of a fire — especially at night when people are sleeping. But many Toronto homes still have expired alarms, missing alarms, battery-only units with dead batteries, or smoke detectors that aren't installed in the right locations. Here's what the Ontario Fire Code requires, and what we see on the job.
Quick Answer
Ontario law requires smoke alarms on every storey and outside all sleeping areas. Carbon monoxide detectors are required on every floor with a fuel-burning appliance or attached garage. Smoke alarms must be replaced every 10 years. Homes with multiple legal units require additional protection including duct smoke detectors. If your alarms are more than 10 years old, chirping, or failing the test button — replace them now.
Where Smoke Detectors Are Required in Ontario
Under the Ontario Fire Code, every residential dwelling must have working smoke alarms in the following locations at minimum:
- On every storey — including the basement, which counts as a storey.
- Outside all sleeping areas — in the hallway adjacent to bedrooms so alarms can be heard while sleeping.
- Inside every bedroom — strongly recommended by Toronto Fire Services, and required in many newer builds and renovations, especially where bedroom doors are kept closed at night.
This applies to detached homes, semi-detached homes, townhouses, and rental properties. Landlords in Ontario are legally required to maintain working smoke alarms in their rental units — failure to do so is a provincial offence.
Carbon Monoxide Detectors: Every Floor, Every Fuel Source
A carbon monoxide (CO) alarm is not the same as a smoke alarm. CO is an odourless, colourless gas produced by fuel-burning appliances — furnaces, boilers, fireplaces, water heaters, gas stoves, generators, and attached garages. You cannot smell it, see it, or taste it. At elevated levels it is lethal.
Ontario law requires CO alarms in any home that contains a fuel-burning appliance or an attached garage. CO detectors must be installed:
- On every floor of the home — not just near the furnace.
- Outside all sleeping areas — so occupants are alerted while asleep.
- Near attached garages — vehicle exhaust is a common CO source.
Many homeowners use combination smoke/CO alarms. These are acceptable, but placement still matters — a smoke alarm is best installed on the ceiling, while CO (being similar in density to air) is best detected at head height. When in doubt, have both dedicated units and combination units, or ask your electrician what makes sense for your home layout.
Smoke Alarms with Strobes: Visual Warning for Better Safety
Some smoke alarms include a visual signaling device — a bright strobe light that flashes when the alarm activates. Instead of relying only on sound, strobe alarms provide a visible warning that can alert people who would not respond to the audible alarm alone.
In newer Ontario homes and renovations, smoke alarms with visual signaling are commonly required in bedrooms. Strobe smoke alarms are especially important in homes with:
For the best protection, smoke alarms should be hardwired, interconnected, equipped with battery backup, and where appropriate, include a strobe. A licensed electrician can confirm what your home requires and ensure the installation meets current Ontario code.
Hardwired vs Battery: Which Type Is Right for Your Home
Battery-Only Smoke Alarms
Common in older homes. Easy to install without an electrician. Entirely dependent on the battery being maintained — a dead or missing battery means zero protection. This is the minimum fallback when hardwiring is not immediately possible, but it should not be a permanent solution in an occupied home.
Hardwired Smoke Alarms with Battery Backup
Connected to the home's electrical system and still function during power outages due to the built-in backup battery. This is the standard for all new construction and renovations in Ontario. The battery backup is a safety net — the primary power is the electrical circuit.
Interconnected Smoke Alarms
When one alarm sounds, all connected alarms in the home sound simultaneously. This is significantly safer in multi-storey homes, homes with basements, and any dwelling where someone sleeping at the far end of the house might not hear a single alarm. Interconnection can be done via hardwired connections or wirelessly, depending on the system.
Connect Smoke Detectors to a Main Lighting Circuit
Hardwired smoke alarms should be connected to a main area lighting circuit — not a dedicated circuit that could trip and go unnoticed for weeks. If the living room lights are out, you know that circuit is off. You immediately investigate. A smoke detector connected to a little-used dedicated circuit could lose power without anyone realizing — and the battery backup alone wouldn't be visible. This is especially important in multiplex units and basement apartments.
Multiplex and Multi-Unit Homes: Additional Requirements
If your home has been converted to contain multiple legal dwelling units — a main unit and a basement apartment, or a triplex — the Ontario Fire Code and Building Code impose additional requirements beyond what applies to a single-family home.
- Smoke alarms in every unit — each dwelling unit must have its own complete smoke alarm coverage, not shared with other units.
- Duct smoke detectors — homes with multiple legal units that share a central HVAC system commonly require a duct-mounted smoke detector inside the supply or return air ductwork. A duct smoke detector detects smoke travelling through the air handling system and shuts the HVAC down to prevent smoke from being distributed throughout the building. This is a critical life-safety device and must be installed by a licensed electrician.
- Fire separation — proper fire separation between units (drywall, fire-rated assemblies) is a requirement, and smoke detector placement must account for this separation.
- Landlord obligations — Ontario landlords must ensure alarms are working at the start of every tenancy and test and maintain them throughout.
Smoke Alarms Expire: Replace Every 10 Years
Smoke alarms have a limited lifespan. The sensing element inside degrades over time, making older alarms less sensitive — or completely non-functional — even if they appear to work. Ontario fire safety guidance is clear: smoke alarms must be replaced every 10 years from the manufacture date.
Find the manufacture date on the back or side of the alarm. If there is no date visible, treat the alarm as expired and replace it. If your home has alarms that are yellowed, dusty, or were there when you moved in and you don't know how old they are — replace them.
Signs Your Smoke Alarm Needs Replacement
Test Your Alarms Monthly — It Takes 10 Seconds
Every smoke alarm has a test button. Press and hold it — the alarm should sound loudly within a few seconds. If it doesn't sound, or sounds weakly, replace the battery first. If it still fails after a fresh battery, replace the entire unit.
The Ontario Association of Fire Chiefs recommends testing smoke alarms monthly and replacing batteries at least once a year (or using 10-year sealed-battery alarms to eliminate the maintenance requirement entirely). Change batteries when clocks change — the "change your clocks, change your batteries" rule is still one of the most practical reminders in residential fire safety.
When to Upgrade Your Smoke Alarm System
Several home projects are the right time to review and upgrade smoke alarm coverage:
Common Questions
Where are smoke detectors required in Ontario homes?
Ontario law requires working smoke alarms on every storey of the home and outside all sleeping areas. For homes with bedrooms far from the hallway alarm, inside-bedroom placement is strongly recommended. Carbon monoxide detectors are required on every floor where there is a fuel-burning appliance or attached garage.
How often should smoke detectors be replaced in Ontario?
Smoke alarms should be replaced every 10 years from the manufacture date printed on the back of the unit. If there is no date visible, the unit is yellowed, chirps constantly, or fails the test button, it should be replaced immediately.
Do smoke detectors need strobes in Ontario?
In newer Ontario homes and renovations, smoke alarms with visual signaling (strobe lights) are commonly required in bedrooms. They are especially important for people who are Deaf, hard of hearing, elderly, or heavy sleepers. A licensed electrician can confirm what your home requires.
What is a duct smoke detector and when is it required?
A duct smoke detector is installed inside a home's HVAC ductwork. In Ontario, it is commonly required in residential buildings with multiple legal units and in some commercial applications. It detects smoke travelling through the air system and shuts down the HVAC to prevent smoke from circulating through the building.
Should smoke detectors be on a lighting circuit?
Yes. Hardwired smoke detectors should be connected to a main area lighting circuit — not a dedicated circuit that may go unnoticed if the breaker trips. If the lights go out, you immediately know that circuit is off. A smoke detector on a dark, unused circuit could have a tripped breaker go undetected for weeks.
What is the difference between a smoke detector and a carbon monoxide detector?
A smoke alarm detects smoke particles from fire. A carbon monoxide (CO) alarm detects CO gas — an odourless, colourless gas produced by fuel-burning appliances, furnaces, attached garages, fireplaces, and water heaters. They are not interchangeable. Combination units detect both but must be installed in the right location for each function.
Need Smoke Detectors Installed or Replaced?
Portman Electric can replace expired smoke alarms, install hardwired smoke detectors, add interconnected and strobe-equipped alarms, install duct smoke detectors for multi-unit homes, and check full smoke and CO alarm coverage during renovations, panel upgrades, basement work, and older-home electrical repairs in Toronto and the GTA.