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Ontario Building Code: What It Means for Windows and Doors

Name: Monaco Windows and Doors
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Ontario’s Building Code changed in a big way on January 1, 2025, when the 2024 edition replaced the version that had been in place since 2012. Most homeowners never read the code, and they don’t need to. But if you’re planning to replace windows, finish a basement bedroom, or swap out an entry door, a few of its rules decide whether the job passes inspection or has to be redone. This guide explains what changed, which Ontario Building Code rules for windows and doors matter most in a house, and how to avoid the mistakes that lead to failed inspections.

What Changed With the 2024 Ontario Building Code

The 2024 Ontario Building Code took effect on January 1, 2025, with a short transition period that ended on March 31, 2025. Since April 1, 2025, new building permit applications have had to meet the new edition. The main goal of the update was to line Ontario up more closely with the National Building Code, and the province says it removed at least 1,730 technical differences between the two.

For homeowners, that means fewer Ontario-only quirks and more rules that match the rest of the country. Many of the changes affect how new homes and larger buildings are designed rather than everyday renovations. The window and door rules below were not rewritten from scratch, but they matter every time you change an opening, add a bedroom, or replace glass in or near a door.

When a Permit Comes Into Play

Permits are issued by your municipality, so the details vary from city to city. In general, replacing a window or door in the same opening of a single-unit house doesn’t need a permit, as long as the size, location, and structural support stay the same. Cutting a new opening, enlarging or moving an existing one, or adding a basement egress window usually does. For the full breakdown, see this guide on whether you need a permit to replace windows or doors in Ontario.

Finding out a permit was needed after the new window is already in is the expensive way to learn. A quick call to your local building department before anything is ordered can save weeks of delays and the cost of opening up finished walls.

Egress Window Requirements for Bedrooms

Every bedroom needs a way out in an emergency. Unless a door on the same floor opens directly outside, each floor with a bedroom needs at least one window that meets the egress rules in the Ontario Building Code:

It opens from the inside without keys, tools, or special knowledge.
It gives an unobstructed opening of at least 0.35 m² (about 3.8 square feet).
No side of that opening is less than 380 mm (about 15 inches).
It stays open on its own, without needing to be propped.
Outside of basements, its sill is no more than 1,000 mm (about 39 inches) above the floor.

Basement windows that open into a window well need at least 550 mm (about 22 inches) of clear space in front of the window, and any cover over the well must open from the inside without tools. The measurements refer to the clear opening, not the overall frame size, which is why a window that looks big enough can still fail. Casement and sliding windows often work best for egress because they open wider than similar-sized awning or hopper units.

For a deeper look, see this guide to egress windows in Ontario homes, or explore basement window replacement and installation if you’re planning a basement bedroom or apartment.

Safety Glass and Window Guards

The code also sets rules for where safety glass is required. Glass in doors, and in sidelites or panels right next to doors, generally has to be tempered or laminated so it breaks safely if someone falls or pushes against it. Shower and tub enclosures and some large, low panes are other common places where tempered or laminated glass is expected.

On upper floors, windows with low sills can be a fall risk, especially for young children. Depending on the height of the sill and the drop outside, the code may call for a guard or an opening limiter that stops the window from opening wide enough for a child to fall through. That’s one more reason to confirm the details before ordering replacement windows with a different style or sill height.

The Door Between the House and an Attached Garage

If your home has an attached garage, the door between the garage and the house has a fire and air-quality job to do. The code expects this door to be tight-fitting and weatherstripped to keep exhaust fumes out, and to have a self-closing device so it doesn’t get left open. It also shouldn’t open directly into a bedroom. Swapping it for a lightweight interior door, or removing the closer, creates a real safety gap.

A garage entry door that no longer latches or seals isn’t just an annoyance. It can let fumes and cold air into your living space every time the car starts, so it’s worth fixing before winter rather than after.

Energy Efficiency Rules and Replacement Windows

Energy efficiency requirements for new houses in Ontario are set out in a supplementary standard to the code known as SB-12, which covers insulation, air tightness, and the performance of windows and doors. When you replace windows in an existing home, you generally aren’t required to bring the whole house up to new-build standards. New windows should still be chosen with performance in mind, since they’ll be in place for decades.

In practice, an ENERGY STAR certified window rated for your climate zone, with Low-E glass and a properly sealed and insulated installation, is a safe choice for most projects. Check the U-factor on the label: the lower the number, the less heat escapes. For more on what to compare, see this guide to energy-efficient window features or this double pane vs. triple pane comparison.

Common Mistakes That Lead to Failed Inspections

Most code problems with windows and doors come from a handful of avoidable mistakes:

Ordering a bedroom window by frame size without checking the clear opening for egress
Enlarging an opening without a permit or a properly sized header
Using regular glass in or beside a door
Skipping flashing, sealing, and insulation around the new frame
Blocking an egress window with a window well that’s too small or a cover that’s hard to open

An experienced installer will know these details and flag them before anything is ordered. When you plan window replacement or new door installation, ask how the work will meet current code and whether a permit is needed.

Build It Right Once and Know It’s Safe

The Ontario Building Code can feel like fine print, but for windows and doors it comes down to a few practical goals: everyone can get out in an emergency, glass breaks safely, fumes stay out, and the house stays warm. Knowing the basics before you start makes conversations with installers and building officials much easier, and your local building department always has the final word on your specific project. If you’re planning a basement bedroom, a larger opening, or a full window or door upgrade, get the details confirmed now, because fixing a code problem after the drywall is up costs far more than getting it right the first time.

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Frequently Asked Questions

When did the new Ontario Building Code take effect?

The 2024 Ontario Building Code took effect on January 1, 2025, replacing the 2012 edition. A transition period let some projects follow the older code until March 31, 2025. Since April 1, 2025, new building permit applications must meet the 2024 code. The update mainly brought Ontario’s rules closer to the National Building Code by removing at least 1,730 technical differences.

Do I need a permit to replace windows in Ontario?

Usually not, if you’re replacing a window in the same opening of a single-unit house without changing its size, location, or structural support. You typically do need a permit to create a new opening, enlarge or move an existing one, or add a basement egress window. Rules are set by each municipality, so check with your local building department first.

What size does an egress window need to be in Ontario?

An egress window must give an unobstructed opening of at least 0.35 square meters, about 3.8 square feet, with no side narrower than 380 millimeters, about 15 inches. It must open from the inside without tools and stay open on its own. Outside of basements, the sill should be no higher than 1,000 millimeters above the floor.

Does a basement bedroom need an egress window?

Yes, in most cases. Unless a door on the same floor leads directly outside, a floor with a bedroom needs at least one window that meets the egress requirements. If that window opens into a window well, the well must leave at least 550 millimeters of clear space in front of it, and any cover must open easily from inside.

Do replacement windows have to meet energy efficiency rules?

Replacing windows in an existing home doesn’t usually require bringing the whole house up to new-build energy standards. Still, new windows should perform well in Ontario’s climate. Choosing ENERGY STAR certified windows rated for your zone, with Low-E glass and a low U-factor, is a safe way to get good efficiency and avoid questions if a permit is involved.

Where is safety glass required in a home?

Safety glass, meaning tempered or laminated glass, is generally required in doors and in glass panels right next to doors, such as sidelites. It’s also commonly needed in shower and tub enclosures and in some large, low panes where people could walk into the glass. Your installer or local building department can confirm exactly what applies to your openings.

What are the rules for the door between a house and an attached garage?

The door between an attached garage and the house should be tight-fitting and weatherstripped to keep exhaust fumes out, and it needs a self-closing device. It also shouldn’t open directly into a bedroom. These rules help slow the spread of fire and protect indoor air, so avoid replacing it with a lightweight interior door or removing the closer.

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