Smoke and CO Alarm Requirements Ontario

The rule applies to owners, landlords, tenants and renovators

Ontario’s smoke and carbon monoxide alarm rules apply to houses, townhomes, condos, basement units and most rental dwellings. The Ontario Fire Code sets the minimum fire-safety duty for existing homes: working smoke alarms must be installed on every storey of a dwelling and outside sleeping areas.

Carbon monoxide alarms are required near sleeping areas when the home has a fuel-burning appliance, a fireplace, or an attached garage. That includes common GTA setups such as a gas furnace in the basement, a gas water heater, a gas fireplace on the main floor, or bedrooms above or beside an attached garage.

The rule is not limited to “old” homes or “new” homes. If people sleep there, the alarms must be present, powered, maintained and not disabled. A finished basement, basement apartment, attic bedroom, converted den or rental room can change what “outside sleeping areas” means in practice.

Electrical work is a separate layer. Replacing a battery alarm with another battery alarm is usually a fire-safety maintenance item. Installing new 120V hardwired alarms, adding interconnect wiring, relocating devices, or tying alarms into a renovation is electrical work that must comply with the Ontario Electrical Safety Code. Where ESA notification is required, the work must be filed, inspected and accepted by the Electrical Safety Authority.

City Power Electrical Services is a Licensed Electrical Contractor under ECRA/ESA #7015314. For alarm replacement and hardwired installation, see our smoke and CO detector installation service.

What compliance requires in practice

A compliant home has the right alarm type, in the right location, with the right power source and interconnection for the situation.

For smoke alarms, the baseline is:

• One working smoke alarm on every storey, including the basement.
• Smoke alarms outside sleeping areas, positioned so they wake people with bedroom doors closed.
• Additional alarms where layout makes one device unreliable, such as long bedroom hallways or separated sleeping areas.
• Devices mounted according to the manufacturer’s instructions, not tucked into dead-air corners.
• Units replaced when expired, damaged, painted, contaminated or repeatedly faulting.

For CO alarms, the practical test is: could carbon monoxide from a fuel-burning appliance, fireplace or attached garage reach a sleeping person? If yes, CO protection is needed near the sleeping area. In many homes the best solution is a combination smoke/CO unit in the bedroom hallway, plus additional protection where the floor plan or appliance layout calls for it.

Device selection matters. A plug-in CO alarm in the wrong hallway does not fix a missing smoke alarm. A battery-only smoke alarm may satisfy some existing-home situations, but it is not the same as a hardwired interconnected system required in many permitted renovations or new construction. A smoke alarm is also not a substitute for a building fire alarm system in a property that requires one.

Modern hardwired residential alarms are usually 120V devices with battery backup. Interconnection means when one alarm senses smoke, the other alarms sound as well. Interconnection can be done with approved wiring between alarms or, in some retrofit situations, with listed wireless-interconnect devices. During renovations, especially when ceilings are open, hardwired interconnected alarms are often the cleanest and most future-proof approach.

If the project is part of a legal second suite, basement rental or major renovation, alarm rules become more detailed because building-code, fire-code and electrical requirements meet. Start with our basement apartment electrical requirements guide if the space will be rented or separately occupied.

Common mistakes and how they are caught

The most common mistake is treating alarms as a “one device per house” item. Ontario’s rule is storey-by-storey and sleeping-area-based. A smoke alarm on the main floor does not cover the basement. A detector inside a furnace room does not necessarily protect a bedroom hallway. A CO alarm beside the garage door may not satisfy the requirement if the bedrooms are upstairs at the other end of the house.

We often see these specific problems:

• No smoke alarm in the basement because it is used only for laundry or storage.
• A finished basement bedroom added without adding alarm coverage outside that sleeping area.
• CO alarms missing in homes with gas furnaces, gas fireplaces or attached garages.
• Plug-in CO alarms installed at an outlet blocked by furniture or too far from bedrooms.
• Expired alarms left in place because the test button still chirps.
• Hardwired alarms removed after nuisance trips, leaving only a blank plate or loose conductors.
• Alarms installed too close to showers, cooking appliances, supply air registers or ceiling fans, causing false alarms or delayed response.
• Mixed alarm models that do not properly interconnect.
• No battery backup, dead backup batteries, or chirping devices with the battery removed.

These issues are caught in different ways. A fire department inspection may catch missing or disabled alarms. A landlord inspection or tenant complaint may raise maintenance and instruction issues. A home inspector may flag missing devices before sale, although a home inspection is not the same as a code compliance inspection. An ESA inspector may review wiring methods, boxes, connections, circuiting and device installation when new hardwired alarms are part of notified electrical work.

If new wiring is being run, the electrical scope needs proper boxes, approved cable, correct connections, mechanical protection where required, and access to the alarm circuit. Splices must be in approved enclosures. Conductors cannot be left loose above a ceiling. If alarms are interconnected by cable, the interconnect conductor must be wired only as permitted by the alarm manufacturer and code-compliant wiring methods.

For the electrical filing side, see the ESA notification process in Ontario.

Landlord, sale, insurance and inspection consequences

For landlords, alarms are not optional and they are not “tenant preference.” The Residential Tenancies Act and Ontario Fire Code place real obligations on landlords to provide and maintain required life-safety equipment. Landlords must make sure alarms are installed, working, maintained and replaced when needed. They must also give tenants the manufacturer’s maintenance instructions or otherwise provide required information about operation and testing.

Tenants also have duties. They must not disable, remove or tamper with required smoke or CO alarms, and they should notify the landlord if an alarm is missing, damaged, chirping or not working. But a landlord should not rely on a tenant to design, install or upgrade required protection.

At sale time, missing alarms can become a negotiation issue or closing condition, especially in older homes, income properties and homes with basement bedrooms. Insurers may also ask about working smoke alarms, CO alarms, knob-and-tube wiring, aluminum wiring, panels and other safety items. If there is a fire or CO incident, disabled or missing alarms can become a serious claim and liability issue.

For electrical work, ESA acceptance matters. When alarm wiring is added during a renovation, the owner should keep the ESA Certificate of Acceptance with the property records. It shows that the notified electrical work passed ESA inspection. It is not a warranty that every fire-code issue in the house is perfect, but it is important proof for the electrical portion. Our guide to the ESA Certificate of Acceptance explains what that document does and does not prove.

Condos add another layer. A suite owner may be responsible for alarms inside the unit, while the condominium corporation may control common-area fire alarm systems, risers, corridors and suite entry devices. Before changing hardwired devices in a condo, check the condominium rules and property manager requirements. Do not disconnect a device that may be part of a building fire alarm or supervisory system.

Commercial, multi-residential and mixed-use properties can require a fire alarm system rather than only residential smoke alarms. Those systems have separate inspection and testing obligations. If that is your building type, start with our Fire Alarm Annual Inspection Ontario guide.

What to do next before renting, selling or renovating

Start with a room-by-room alarm map. Walk every level of the home and mark each storey, every sleeping area, each bedroom hallway, fuel-burning appliance, fireplace and attached garage. Then check the device type, expiry date, power source and whether alarms sound together.

Before renting or selling, fix obvious deficiencies first:

• Add missing smoke alarms on storeys and outside sleeping areas.
• Add CO alarms near sleeping areas where the home has a gas, oil, propane or wood-burning appliance, fireplace or attached garage.
• Replace expired, painted, damaged or unreliable alarms.
• Install combination smoke/CO units where they make sense for the layout.
• Keep manuals, receipts and ESA documents with the home records.

Before renovating, decide whether alarm wiring should be included while walls or ceilings are open. This is especially important in basement finishing, second-suite work, bedroom additions and main-floor renovations where pot lights, new circuits and ceiling work are already happening. Adding hardwired interconnected alarms during the project is usually cleaner than fishing cable later.

City Power provides free written estimates, files ESA notifications where required, installs approved devices, completes the wiring cleanly and cleans up when the work is done. We replace expired detectors with combination smoke/CO units that have battery backup, typically $90–$150 per unit installed. Larger hardwired or renovation scopes are quoted in writing after a site visit.