Egress Window Requirements Ontario: 2025 Building Code

A Homeowner's Guide to Egress Window Requirements in Ontario (2025 Building Code)

If you're planning a basement renovation in Ontario to create a new bedroom, in-law suite, or legal apartment, you're going to become very familiar with one word: "egress." An egress window is a window that is large enough and accessible enough to be used as an emergency exit in case of a fire. It is not optional—it is a critical, non-negotiable life-safety requirement mandated by the Ontario Building Code (OBC).

Understanding the specific egress window requirements in Ontario is the most important step in planning your renovation. Failure to comply doesn't just put your family or tenants at risk; it will also cause you to fail your building inspection, potentially forcing you to re-do expensive work. This 1000+ word guide will break down the OBC requirements in simple, easy-to-understand terms.

Disclaimer: This article is for informational purposes only and is based on the Ontario Building Code at the time of writing. The OBC is subject to change, and local municipalities (like Toronto or Mississauga) may have additional by-laws. Always consult with a professional contractor and your local building department before starting any construction.

When Do You Need an Egress Window in Ontario?

The Ontario Building Code is very clear. You MUST install an egress window in two main situations:

1. Every Bedroom: Every bedroom in a house must have at least one window or door that opens directly to the outside, which is suitable for egress. This applies to bedrooms on *any* floor, but it is most commonly a factor in basement renovations.
2. Finished Basements: If you have a finished basement that does *not* contain a bedroom (e.g., just a rec room), the basement itself must have an egress window or a door to the outside. If the basement *does* contain a bedroom, that bedroom's egress window satisfies the requirement for the entire basement, provided there isn't a separate suite.

If you are creating a second, self-contained apartment or "accessory unit" in your basement (a legal basement apartment), the rules are even more stringent and require specific fire separations and a clear path of escape, of which the egress window is a key part.

The 4 Key Ontario Egress Window Requirements

The OBC doesn't just say "install a big window." It has four very specific, measurable rules that your window and its installation must follow.

1. The "Unobstructed Opening" Size (The Most Important Rule)

This is the part that confuses most people. The rule is not about the size of the window frame; it's about the size of the clear, open space you can climb through when the window is fully open.

The OBC states that the unobstructed opening must have a minimum area of 0.35 square metres (which is 3.77 square feet).

But that's not all. There's also a minimum dimension rule:

• No single dimension (height or width) of that opening can be less than 380 mm (15 inches).

This is to ensure a firefighter with equipment can fit through. A window that is very wide but not very tall (like a 40" x 14" slider) might meet the *area* requirement but would fail the *dimension* requirement, because 14 inches is less than 15. This is why slider windows are very difficult to use for egress, as one pane is always blocking the other, and you only get just under half the total window area as an opening.

2. The Window Sill Height

The OBC dictates how high the window can be from the floor.

• The bottom of the window opening (the sill) cannot be higher than 1.5 metres (59 inches or 4.9 feet) above the floor.

This is to ensure an average person can climb out. If your window sill is higher than this, you must build a permanent, sturdy step or platform below it to meet the code.

3. It Must Open Easily (No Special Tools)

The window must be able to be opened from the inside without the use of any keys, tools, or special knowledge. It must be a simple latch or crank that anyone can operate in a panic.

4. The Window Well Requirement (If Below Ground)

This is critical for all basement egress windows. If the bottom of your window opening is below ground level, you MUST install a window well outside. That window well *also* has its own set of rules:

• The window well must project outwards from the house wall at least 760 mm (30 inches).

This is the most-failed part of an inspection. This 30-inch space provides the room needed to open the window fully (especially a casement window) and for a person to physically climb out. A small, 18-inch "half-moon" well is not compliant for an egress window.

Furthermore, if the window well is deeper than 1 metre (39 inches) from the ground down to the bottom, you must securely attach a permanent ladder to the wall to allow for escape.

What Are the Best Window Types for Egress?

Given the strict "unobstructed opening" rules, some window styles are far better than others. A professional window installer will almost always recommend one of these two options:

1. Casement Windows (The Best Choice)

A casement window is the ideal choice for egress. It's hinged on the side and cranks outward, like a door. When fully open, the *entire* window sash swings out of the way, leaving you with a 95-100% clear, unobstructed opening. This means you can meet the 3.77 sq. ft. opening requirement with a much smaller, more affordable window. For example, a casement window as small as 24" x 24" can often be code-compliant.

2. In-Swing or "Hopper" Windows

These windows are hinged at the bottom and pull open *into* the room. Like a casement, the entire sash moves out of the way, giving you a full-frame opening. They are a great solution, but you must account for the space they take up inside the room when open.

Window Types to Avoid for Egress

• Slider Windows: The worst choice. To get a 3.77 sq. ft. *opening*, you would need a window that is over 7.5 sq. ft. in total area (e.g., a massive 48" x 48" window), which is often not feasible in a basement.
• Double-Hung Windows: Better than a slider, but you can still only open one half at a time. This requires a very large, tall, and expensive window to meet the code.

Don't Forget About Installation

Installing an egress window in a basement is a major construction project. It involves:

• Excavating a large hole for the window well.
• Cutting a new opening in your concrete foundation. This is a structural task that requires a professional with the right concrete saws, drills, and knowledge.
• Installing a new lintel (a steel beam) above the window to support the weight of the house.
• Properly waterproofing and sealing the new window and frame against the concrete.
• Installing the window well, backfilling with gravel for drainage, and ensuring drainage is tied into your home's weeping tile system.

This is not a DIY job. The risks of structural damage or a major basement flood are extremely high if this is done incorrectly. A professional, full-service company will handle the excavation, concrete cutting, and installation as one seamless project, and will ensure it passes inspection.

The Bottom Line: Safety First

The egress window requirements in Ontario may seem complex, but they have one simple purpose: to save lives. A fire in a basement can be impossible to escape through a single staircase. The egress window is the second, vital way out.

By investing in a code-compliant egress window, you are not just adding value to your home and creating a legal, usable living space; you are providing a critical safety feature for your family or your tenants. Always work with a professional who understands the OBC and can guarantee their work will pass inspection.