Montreal Gas Ban in New Buildings: What It Means

A developer files plans for a new office building in a Montreal borough. The mechanical spec calls for the usual: a natural gas boiler and a few gas-fired rooftop units. Except the plans won’t clear the permit review. Since April 1, 2025, the Montreal gas ban in new buildings has been in force, and it covers commercial construction just as much as residential. For a property manager or developer, the question is no longer “which gas appliance do I choose?” but “how do I heat a new building without combustion?” Many find out at the worst possible moment — once the plans are already drawn.

This is not an administrative footnote. It reshapes the mechanical design of every new project on City territory, redefines the role of natural gas, and shifts the bulk of the heating load onto electricity. Here is what the by-law prohibits, what it lets through, and how to approach a new project without getting caught out.

Can you still install a gas boiler in a new building in Montreal?

No, with limited exceptions. Since April 1, 2025 (and October 1, 2024 for small buildings), the City’s by-law on greenhouse-gas emissions from new buildings prohibits, in new construction, any appliance for space heating, water heating, cooking or clothes drying that runs on natural gas, fuel oil, propane or biodiesel. The ban covers the residential, commercial and institutional sectors.

In other words, combustion is no longer the default in new construction: it is the exception, hemmed in by specific conditions. A project built by reflex around a gas boiler room will have to be rethought before it even reaches the permit stage.

What the by-law bans — and from when

The ban phased in over two dates, based on building size. A small building, under the National Building Code, is no more than three storeys and 600 m² per floor; beyond either threshold, it is a large building. The by-law applies across the 19 boroughs of the City of Montreal — a territory that holds a major share of the commercial building stock in the Greater Montreal area.

What the ban captures is not just boilers. The text targets any combustion appliance emitting GHGs for space heating, water heating, food cooking and clothes drying. A gas furnace, a gas water heater, a residential gas range, an indoor gas fireplace: all are covered in a new building. For a commercial property, that means rethinking heat and domestic hot water production as a single system.

The exemptions that matter to a property manager

A by-law is understood as much through its exemptions as through its rule. Several situations remain permitted, and they can make all the difference to a project:

• Renewable-source gas in large buildings: a large building may install gas appliances if the emissions come solely from renewable-source gas. The owner must keep and provide on request proof of supply — for instance, the energy supplier’s contract.
• Hydro-Québec connection delay: if the electrical connection takes more than twelve months after the permit is issued, a small building may likewise fall back on renewable-source gas.
• Emergency generators and certain commercial cooking appliances (restaurants, bakeries) remain allowed.
• Industrial buildings and buildings tied to a district thermal network: excluded from the by-law.
• Existing buildings: not covered. The by-law touches new construction only — modernizing an existing boiler room stays fully possible, on gas or electric.

Finally, projects whose complete permit application was filed before the phase-in dates are exempt. The permit filing date thus becomes strategic data, not a mere formality.

Why is Montreal tightening the screw now?

The by-law does not stand alone: it is part of the City’s roadmap toward zero-emission buildings by 2040. Building heating weighs heavily on Montreal’s carbon balance, and targeting new construction avoids having to convert, later, a stock that was allowed to be built on gas. It also aligns with the provincial direction: Quebec already regulates the replacement of oil-heating systems in existing buildings, another signal of an accelerating transition.

On the ground, this timing collides with a Montreal reality: cooling demand rising with each summer heat wave, and an electrification of heating already well underway, backed by active incentive programs. The result is that the heat pump — which both heats and cools — becomes the centrepiece of the new building, where gas once held that place. Between this municipal by-law and the 2026 update to the RBQ gas code, the message is clear: the regulatory frame around heating is tightening on several fronts at once.

Field case: the new project that had to be redrawn

A developer of a small three-storey commercial building in Montreal’s east end came to us in spring 2025. The mechanical concept, drawn the year before, relied on gas rooftop units and a gas water heater — the usual, proven, cheap-to-buy configuration. The catch: the permit application had not yet been filed, and the project now fell under the ban.

Rather than absorb the constraint late, the team built it in early. Heat production was redrawn around heat pumps, the electrical load reassessed with Hydro-Québec to confirm the connection timeline, and domestic hot water handed to an electric solution. The equipment premium, real at the outset, was partly offset by electrification incentives and by dropping the gas connection and its servicing. A year earlier, the same building would have been built on gas by default; the by-law forced a design that the building’s life cycle justified anyway.

How do you heat a new building without gas?

The dominant alternative is the commercial heat pump, in air-to-air or air-to-water form, sized for Montreal’s climate and often paired with electric backup for deep-cold peaks. Sizing becomes the number-one issue here: an undersized heat pump disappoints at −25 °C, while an oversized one costs more and cycles poorly. This is exactly the kind of project where energy optimization carried out at the design stage pays off across the whole life cycle.

For large buildings, the renewable-source-gas route keeps the fuel on the table, provided supply is secured — a scenario close to a dual-energy setup in commercial and institutional buildings, where gas and electricity share the load by season and energy price. The choice never boils down to “gas or electric”: it depends on building size, load profile and available incentives, which we break down in our piece on heat pump subsidies for rental buildings.

The question to ask at the concept stage

For a new project in Montreal, stop asking “which gas boiler do I install?” and start asking “is this building small or large under the by-law, and which electric strategy holds up for its load profile?” Ask it before you freeze the mechanical concept and before you file the permit — that is when a redesign costs the least. Check the filing date of any project already in the pipeline, too: a few weeks can decide which regime applies.

At Montréal Combustion, we guide managers and developers across Greater Montreal through this shift — sizing heat pumps, weighing electric against renewable-source gas for large buildings, and folding in incentive programs — so a new project clears the permit stage without surprises and stays viable over twenty years.