Ontario’s New CO Alarm Law — What Every Markham Homeowner and Landlord Must Do Right Now

This is not a future compliance requirement. It is already the law. Beginning January 1, 2026, all homeowners, landlords, and residential building managers in Ontario are required to meet updated Carbon Monoxide alarm installation requirements under the Ontario Fire Code, aimed at strengthening public safety. If you own a home in Markham, rent a property to tenants, or manage a condominium unit, you need to read this and act — because non-compliance carries real penalties and, more importantly, real danger.

Michael John Lau, Markham’s top REALTOR® and CPA/CMA, ensures every buyer and seller client understands this requirement — because CO alarm compliance affects listing inspections, home insurance coverage, and the legal obligations of every Ontario landlord.

What Changed on January 1, 2026

Under the updated Ontario Fire Code, carbon monoxide alarms are now required on every floor. Previously, CO alarms were only required near sleeping areas. As of January 1, 2026, a working CO alarm must be installed on every storey of a home, including basements and floors without bedrooms.

The sleeping-area protection requirement did not disappear — it was expanded. A CO alarm must still be installed adjacent to each sleeping area, in addition to the new every-floor requirement.

In plain language for a typical Markham three-storey detached home: you need a CO alarm on the main floor (even if no one sleeps there), one outside each sleeping area on the second floor, and one in the basement — even if the basement has no gas appliances in it directly.

Which Homes Does This Apply To

Ontario expanded carbon monoxide alarm requirements through Ontario Regulation 87/25, amending the Fire Code O. Reg. 213/07. Under the new update, if you live in a detached home, semi, townhouse, cottage, or similar dwelling with a fuel-burning appliance, a fireplace, an attached garage, or heating supplied by a fuel-burning appliance, you must install a CO alarm on every storey of the home, including basements and floors without bedrooms.

As of 2026, every residential unit in Ontario must have carbon monoxide alarms, regardless of building type or mechanical systems. This change has major implications for condo management and multi-residential properties.

Your Specific Obligation as a Markham Homeowner

Walk your home today. Count the floors — basement, main floor, upper floors. You need a working CO alarm on each one. Open the packaging, install it per the manufacturer’s instructions, and test it using the test button before treating it as operational. You should test your alarms monthly using the test button and replace batteries at least once a year, unless you have a 10-year sealed battery model.

For Markham homes with natural gas furnaces, gas water heaters, gas fireplaces, or attached garages — which describes the overwhelming majority of Markham’s detached housing stock — the January 1, 2026 requirement is unambiguous: every floor needs a working alarm.

Combination smoke-and-CO alarms satisfy both requirements simultaneously and are available at Canadian Tire, Home Depot, and most hardware and grocery stores across Markham for $25 to $60 per unit.

Your Specific Obligation as a Markham Landlord

Homeowners must install and maintain compliant CO alarms in their homes. Landlords bear responsibility for installing and maintaining CO alarms in rental units.

Renters should test alarms monthly and report any concerns to their landlord, who remains responsible for installing and maintaining CO alarms in rental units.

If you rent out a Markham home, a basement apartment, or a condo unit, the installation and ongoing maintenance obligation is yours as the landlord — not the tenant’s. If a tenant reports that a CO alarm is not working, you must respond promptly and replace it. Failure to maintain compliant CO alarms in a rental unit is a breach of your obligations under the Ontario Fire Code and the Residential Tenancies Act simultaneously.

For Markham landlords with secondary suites — basement apartments — both the main unit and the secondary suite require compliant CO alarms on every floor. A secondary suite with one CO alarm adjacent to the sleeping area but none on the basement floor itself does not meet the 2026 requirements. Both units, all floors.

The Insurance and Legal Implications

Most insurance contracts require you to maintain your home according to local safety laws. Failure to have working CO alarms as required by the Ontario Fire Code can affect your coverage.

An insurance claim related to CO exposure — or any other claim — in a home where the Fire Code’s CO alarm requirements are not met creates genuine coverage risk. The insurer may deny a claim on the basis that the homeowner was not in compliance with applicable safety legislation. In a rental unit context, the landlord’s personal liability exposure for CO-related injury to a tenant in a non-compliant property is significant.

Failure to comply can result in fines ranging from several hundred dollars to more severe penalties for repeated violations.

CO Alarm Compliance and Markham Real Estate Transactions

Michael John Lau, Markham’s top REALTOR®, includes CO alarm compliance in the pre-listing preparation checklist for every Markham seller. A home inspector who finds non-compliant CO alarm installation during a buyer’s home inspection will include it in the report — creating a post-inspection negotiation issue that is entirely preventable with a $40 alarm installation before listing.

For buyers, CO alarm compliance is a standard item to verify during the home inspection condition period. For sellers, compliance is a prerequisite to a clean inspection report. Act now — not when a buyer’s inspector flags it.

Frequently Asked Questions

What is the new CO alarm law in Ontario for 2026?

As of January 1, 2026, carbon monoxide alarms are required on every storey of a home, including basements and floors without bedrooms, in addition to the existing requirement near sleeping areas.

Do electric-only condos need CO alarms under the new law?

Yes. The legislation covers all residential units. Even if your unit is entirely electric, shared building mechanical systems may create CO risk, so every residential unit must have compliant alarms on every floor.

Who is responsible for CO alarms in a Markham rental property?

The landlord is solely responsible for installing and maintaining compliant CO alarms in rental units. Tenants should test them monthly and report issues, but the legal obligation rests entirely with the property owner.