How Warm Does an Ontario Rental Have to Be? “20 Degrees” Is Three Rules Stacked, Not One
Everyone repeats the same number — 20 degrees — as if it settled the question. It doesn’t. The rule isn’t in force year-round, it doesn’t bind every unit, and your city gets the last word. Here’s the number pulled apart into the three switches that actually decide your case.
My unit feels cold and my landlord says it’s fine — when we disagree, who actually has to prove whether the heat is legally enough, and does that flip depending on the season or on which of us controls the thermostat?
Short version: “the law says 20 degrees” is true just often enough to walk tenants into trouble. Whether your landlord is actually offside turns far less on the reading than on a handful of facts sitting around it.
Heat is only a legally required vital service from September 1 to June 15 (O. Reg. 516/06 s.4(1)); inside that window the bar is a minimum of 20°C, and it is read at a fixed spot — 1.5 m above the floor and 1 m from an exterior wall (s.4(2)), not at the coldest corner you can find. The part most people miss is who it stops applying to: where you can work your own thermostat and the primary system is capable of hitting 20°C, s.4(3) drops that 20°C guarantee off your unit entirely, because the temperature is now your call.
The duty that comes with no conditions attached is somewhere else again — RTA s.20(1) makes the landlord keep the place fit to live in all year, and your city’s by-law can demand more on top: Toronto sets the floor at 21°C, a degree above the province.
Sources (primary, current e-Laws consolidation): Ontario Residential Tenancies Act, 2006, S.O. 2006, c. 17, ss. 2(1) (definition of “vital service”), 20(1)–(2) (repair duty), 21(1) (no withholding of a vital service) and 31(1)(d) (administrative-fine formula); O. Reg. 516/06, s. 4(1)(2)(3) (heating season, 20°C standard, tenant-controlled exception); City of Toronto Municipal Code Chapter 497 (Indoor Temperature Standards). Verified against primary sources, September 2026.
I’m Arthur Zhao, a broker in the Toronto area. Here’s the scene this rule is really about: it’s February, your unit feels cold, and your landlord insists the building is perfectly warm. Now what? Somebody has to show whether the heat is legally short — and that, not the number on the wall, is where these disputes are actually won or lost.
What catches people off guard is how much rides on facts that have nothing to do with today’s temperature: whether heat is even legally required in this stretch of the calendar, whose hand is on the thermostat, and whether your municipality asks for more than the province does. A tenant who knows those answers walks into the argument holding evidence; one who only knows “the law says 20” often walks in with nothing. This piece lays out what the landlord actually has to deliver, who has to prove what when the two of you disagree, what the rules do and don’t say about a unit that runs too hot, and the two routes for forcing a fix.
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Why “20 degrees” is the wrong thing to memorize
“Doesn’t Ontario require 20 degrees? Mine’s colder, so my landlord is breaking the law.” That’s the sentence I hear most, and the problem isn’t the number — it’s that it turns a rule full of conditions, seasons and an exception into a flat, absolute law.
Start with a distinction most people skip. The one duty that really is unconditional — keeping the unit in a good state of repair, fit to live in, and compliant with health and maintenance standards — is not in the temperature regulation. It’s in RTA s.20(1), and by s.20(2) it applies even if you knew about the defect before you signed. The “20 degrees” rule (O. Reg. 516/06 s.4) is a different animal: it’s a clock that decides when heat counts as a vital service, hooked onto the definition of a vital service and the ban on cutting one off.
Keep those two apart and you’ll reach for the right hook when you complain. Here are the three layers.
Heat is a “vital service” — but only for part of the year
RTA s.2(1) defines a vital service as hot or cold water, fuel, electricity, gas — and, for the part of the year the regulations set, heat. That last clause matters: heat isn’t a vital service all year, only inside the prescribed window.
O. Reg. 516/06 s.4(1) fixes that window at September 1 to June 15. During it, heat is a vital service, and RTA s.21(1) kicks in: a landlord shall not withhold the reasonable supply of it or deliberately interfere with it.
How cold is too cold? The standard lives in the regulation, and I unpack it next — but the headline is that a vital-service breach and a temperature-standard breach are two different failures, and knowing which one you’re looking at decides which remedy you reach for.
ℹ️One distinction worth drawing early: this article is about heat that is present but inadequate — a unit that never reaches the required temperature. That is a different problem from a landlord shutting the heat off entirely or deliberately interfering with it, which is its own prohibition under RTA s.21(1) and is treated more severely. If your heat has been cut off rather than merely running cold, you’re in withholding-of-a-vital-service territory, not a maintenance-standard shortfall.
The 20°C standard — and exactly where it gets measured
O. Reg. 516/06 s.4(2) is the part everyone quotes: during the heating season the landlord must keep the room temperature at a minimum of 20°C. Two details in that subsection get overlooked and change outcomes.
Where it’s measured. The 20°C is read 1.5 metres above floor level and one metre from an exterior wall — not at the draughty gap under a window or the coldest square inch of the floor. If your thermometer is on the sill, you’re not measuring what the rule measures.
Which spaces count. All habitable space, plus any area intended for normal use by tenants — the subsection expressly includes recreation rooms and laundry rooms and expressly excludes locker rooms and garages. So a freezing shared laundry room is inside the rule; an unheated garage is not.
The exception that trips people up: tenant-controlled units
This is the layer people miss, and it’s the one most likely to sink a complaint. O. Reg. 516/06 s.4(3) says the 20°C standard in s.4(2) does not apply to a unit where the tenant can regulate the temperature and the primary source of heat can maintain a minimum of 20°C.
The logic is straightforward: if you set the temperature, the law stops asking the landlord to vouch for whatever number is on the wall right now. Turn it down to 18 to save on the bill and that’s your call — you can’t later claim the landlord fell short.
But stare hard at the “and.” The carve-out needs both conditions at once: you can control it, and the primary system is capable of hitting 20°C. Hand a tenant a furnace that can’t reach 20 no matter how high the dial goes, and s.4(3) won’t rescue the landlord — the equipment itself falls short, regardless of who’s turning the knob. Separating “I chose to run it cool” from “the system can’t get there” is the whole game in this layer.
Summer heat, and the duty that never takes a holiday
Flip the question — too hot instead of too cold — and the provincial answer is blunt: nothing. O. Reg. 516/06 governs heating only. It sets no maximum temperature and no duty to provide cooling or air conditioning. (The one place AC appears is as a service a landlord may charge separately for, and in a capital-expenditure useful-life table — neither is an obligation to supply it.)
Don’t read that as “nobody regulates summer heat.” Cities can, and Toronto now does: under Chapter 497 (renamed the Indoor Temperature Standards by-law as of June 1, 2026), where the owner already provides air conditioning, it must be run from June 1 to September 30 to hold no more than 26°C — and RentSafeTO buildings that don’t offer cooling but have an indoor amenity space must keep that space at or below 26°C over the same period. Crucially, none of this forces a landlord to install AC where there is none.
Now the winter mirror image. Since heat is a vital service only from September 1 to June 15, is a landlord off the hook for a broken furnace between June 16 and August 31? No. The vital-service clock (s.21 with s.4(1)) does pause — but the repair duty in RTA s.20(1) runs all year, and so do municipal property standards. A furnace that dies in July still has to be fixed; your hook in summer is simply the repair duty, not the seasonal vital-service rule.
If the landlord won’t act: two routes that run at the same time
💡 Here’s my honest take, having sat on both the landlord and the tenant side of this: the fight is almost never about the number — it’s about who has to prove what. If the landlord supplies and controls the heat, the practical burden sits on them to deliver a warm unit, so your job is evidence: a cheap logging thermometer read at the right height beats a single phone screenshot, put every complaint in writing, and run a municipal complaint and a T6 at the same time. But if you control your own thermostat, the ground shifts under you. Under s.4(3) the landlord no longer answers for the reading at all, and your case only survives if you can show the primary heating system simply cannot reach 20°C no matter where you set the dial — a much harder thing to prove, and a completely different argument. And before any of it, check whether your city lifts the bar: in Toronto the figure you hold them to is 21°C, not 20. Work out which of these situations is yours first, because it decides not just whether you have a case but what you would have to prove to win it — and if it drags on, get a licensed agent or a lawyer to line up the evidence with you rather than arguing from a slogan.
The fine — and why the number you’ll read online is wrong
If the landlord’s conduct crosses the line into withholding or deliberately interfering with heat as a vital service (s.21), the Landlord and Tenant Board can impose an administrative fine under RTA s.31(1)(d) — and it’s a moving formula, not a fixed cap. It’s the greater of $10,000 and the Small Claims Court monetary limit.
That second figure just moved. The Small Claims limit rose to $50,000 on October 1, 2025 (O. Reg. 626/00 s.1(1), as amended). So the effective ceiling today is $50,000 — yet the LTB’s own Guideline 6 still prints $25,000, which now lags the statute. Read the formula in the Act, not the stale number in the guideline.
One boundary to keep straight: this fine attaches to withholding-type conduct. A plain temperature shortfall that never rises to “cutting off a vital service” is usually met with a rent abatement and a repair order through the T6 route — which is exactly why telling the two failures apart, from the very first section, is worth the effort.
⚠️Look this up and you’ll likely see a maximum administrative fine of $25,000 — that figure sits in the LTB’s Guideline 6 and is now out of date. The Act itself, at s.31(1)(d), sets the fine as the greater of $10,000 and the Small Claims Court limit, and that limit rose to $50,000 on October 1, 2025. Trust the statute’s formula, not the stale number in the guideline.
- Ontario Residential Tenancies Act, 2006, S.O. 2006, c. 17: s. 2(1) (vital service), s. 20(1)–(2) (year-round repair duty), s. 21(1) (no withholding/interference), s. 29 (tenant application, Form T6), s. 31(1)(d) (administrative-fine formula)
- O. Reg. 516/06 (GENERAL, under the RTA), s. 4: s.4(1) heating season Sep 1 – Jun 15, s.4(2) minimum 20°C and how it is measured, s.4(3) exception for tenant-controlled units
- Small Claims Court limit of $50,000: O. Reg. 626/00, s. 1(1) (as amended by O. Reg. 42/25, in force October 1, 2025)
- City of Toronto Municipal Code Chapter 497 (Heating; renamed Indoor Temperature Standards as of June 1, 2026): minimum 21°C from Oct 1 – May 15; where AC is provided, maximum 26°C from Jun 1 – Sep 30
- Further reading: Landlord and Tenant Board Form T6, Tenant Application about Maintenance
Repairs in an Ontario Rental: Landlord vs Tenant — Who Pays for What →Ontario’s Winter Disconnection Ban — and the Landlord Who Doesn’t Pay the Bill →Can an Ontario Landlord Put Cameras on a Rental Property? The Law That Actually Decides It Isn’t Privacy Law →First-Time Renter Guide →
Frequently Asked Questions
What temperature does my landlord actually have to keep — 20°C or 21°C?
Both, depending on where you live. The provincial floor (O. Reg. 516/06 s.4(2)) is at least 20°C during the heating season. A municipality can set a higher bar: Toronto’s Chapter 497 requires at least 21°C. Where both apply, the stricter one wins, so in Toronto you can insist on 21. The dates differ too — the province runs September 1 to June 15, Toronto runs October 1 to May 15. (Source: O. Reg. 516/06 s.4; City of Toronto Municipal Code Chapter 497.)
My unit has its own thermostat that I control. Does the landlord still guarantee 20°C?
Usually not for the exact reading. O. Reg. 516/06 s.4(3) switches off the 20°C standard for a unit where the tenant can regulate the temperature and the primary heat source is capable of maintaining at least 20°C. Read that “and” carefully: the system itself must be able to reach 20°C. If the furnace can’t get there no matter how high you set it, the landlord is still offside and s.4(3) won’t save them. (Source: O. Reg. 516/06 s.4(3).)
It’s the middle of summer and the heating system is broken — does the landlord have to fix it now, out of season?
Yes. Heat only counts as a vital service between September 1 and June 15 (O. Reg. 516/06 s.4(1)), but the landlord’s duty to keep the unit in a good state of repair, fit to live in, and compliant with health and maintenance standards — RTA s.20(1) — runs all year, and municipal property standards apply year-round too. So a furnace that fails in July still has to be repaired; your hook in summer is the repair duty, not the vital-service rule. (Source: RTA s.20(1); O. Reg. 516/06 s.4(1).)
Isn’t this the same as a landlord shutting off my heat?
No — two different problems with two different rules. A landlord who cuts off or deliberately interferes with heat during the vital-service season is breaching RTA s.21(1), which can draw the administrative fine under s.31(1)(d). This article is about heat that runs but never reaches the required temperature — an inadequate-supply / maintenance-standard problem, handled mainly through repair orders and rent abatement. The remedy you reach for depends on which of the two you’re actually facing. (Source: RTA s.21(1), s.20(1).)
How big a fine can the landlord face?
For withholding or interfering with a vital service, RTA s.31(1)(d) sets the administrative fine at the greater of $10,000 and the Small Claims Court monetary limit — and that limit rose to $50,000 on October 1, 2025. Ignore the $25,000 figure still printed in the LTB’s Guideline 6; it lags the statute. Note the fine attaches to withholding-type conduct under s.21; a plain temperature shortfall is usually met with an abatement and a repair order instead. (Source: RTA s.31(1)(d); O. Reg. 626/00 s.1(1).)
Arthur Zhao
Real Estate Broker · FRI · ABR · SRS · PSA · MCNE · E-PRO · CLHMS & GUILD Elite · REAIS
VP & Branch Manager, Bay Street Group Inc.
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