Quick answer
An Ontario landlord who supplies the heat must keep a rental at 20 °C or warmer from September 1 to June 15 under O. Reg. 516/06 of the Residential Tenancies Act, measured 1.5 metres above the floor and one metre from exterior walls. Municipal bylaws add their own figures: Toronto requires 21 °C from October 1 to May 15, while Burlington, Hamilton, Mississauga and Brampton set 20 °C.
The temperature a landlord must keep a rental in Ontario is at least 20 °C wherever the landlord is the one supplying the heat. That figure comes from provincial regulation, and each municipality layers its own bylaw on top with its own dates. We repair heating systems and are not lawyers, so treat the legal summary here as a guide and check the current bylaw for your city.
The provincial rule: 20 °C from September 1 to June 15
The Residential Tenancies Act treats heat as a vital service for part of the year, and O. Reg. 516/06, section 4, sets that period as September 1 to June 15. During it, heat must be provided so the room temperature is at least 20 °C, measured 1.5 metres above the floor and one metre from exterior walls. The rule covers all habitable space and areas tenants normally use, including recreation and laundry rooms, but not locker rooms or garages.
There is one exception written into the same section. The measurement rule does not apply to a unit where the tenant can regulate the temperature and the primary heat source can maintain 20 °C. Put plainly: if the tenant has the thermostat and the system can hold 20 °C, the landlord has met the standard even when the tenant chooses 18 °C.
What the Burlington, Hamilton, Mississauga, Oakville, Brampton and Toronto bylaws say
Each municipality sets its own figure and dates. These were read from the official bylaws and city pages on October 1, 2026:
- Burlington: Property Standards By-law 028-2009 requires at least 20 °C in residential rental buildings from September 15 to May 31.
- Hamilton: Heat By-law 04-091 requires at least 20 °C from September 15 to May 15, supplied by a safe, permanent heating appliance.
- Mississauga: Adequate Temperature By-law 0110-2018 defines adequate heat as at least 20 °C, and the City states that landlords must maintain it throughout the year. The same bylaw defines adequate cooling as no more than 26 °C.
- Oakville: the Town's summary of its Property Standards By-law says landlords must have heating facilities capable of maintaining 20 °C.
- Brampton: Vital Services By-law 68-2018 requires 20 °C, measured the same way as the provincial rule, from September 15 to June 1.
- Toronto: Municipal Code Chapter 497 requires 21 °C in all areas of the unit from October 1 to May 15. Those dates were amended in December 2024; older articles still quote September 15 to June 1.
Where a bylaw and the provincial regulation differ, a landlord has to satisfy both. In practice that means 20 °C from September 1 to June 15 anywhere in the province, and 21 °C in Toronto during the city's window. Bylaws are amended, so confirm the current consolidation with the municipality before relying on a date.
What the 20 °C rule means for the heating equipment
The equipment has to be able to hold the setpoint in every habitable room, on the coldest night, without help from plug-in heaters. Ontario's maintenance standard, O. Reg. 517/06, says every residential complex must have heating equipment capable of maintaining the required temperature, and that no rental unit may have portable heating equipment as its primary source of heat. Burlington's bylaw uses nearly the same words. A space heater is a stopgap during a repair, not a heating system.
From the technician's side, the units that fail a temperature check are rarely short of furnace capacity overall. They are short of delivery to one space:
- A basement apartment at the end of long duct runs, controlled by a thermostat upstairs that shuts the furnace off before the basement warms up.
- A bedroom over a garage or an addition with one undersized supply and no return.
- Radiators that are air-bound or a zone valve that has stopped opening on a boiler system.
- Electric baseboards too small for the room after a renovation.
The fixes are specific: air balancing to push more air to the cold rooms, an added supply or return, a zone, or a ductless head for the room that never keeps up. Who controls the thermostat is its own question, covered in whether a landlord can control the thermostat.
How to measure it, and what to do if the unit is under 20 °C
Use a simple digital thermometer at about chest height, one metre in from an outside wall, away from registers and sunlight. Write down the reading, the date, the time and the outdoor temperature. Tenants should send that to the landlord in writing first; the steps after that are in how long a landlord has to fix the heat.
Landlords should treat a reading under 20 °C as a service call, not a debate. A furnace diagnostic is $90–$150, credited toward the fix, and most furnace repairs run $150–$800. Our overview of landlord HVAC responsibilities in Ontario covers the wider duties. For furnace repair at a rental in Burlington, Hamilton, Oakville, Mississauga or Brampton, call (647) 801-1252 or send us the address and the readings.