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Your Basement Has a Window. But Is It Actually Suitable for Egress?
A lot of Ottawa basements already have windows. They might bring in a little daylight, slide open for some fresh air and do their job perfectly well for years. Then you decide to finish the basement, add a bedroom or start thinking about a rental suite — and suddenly that little window becomes a much bigger part of the conversation.
That’s where egress windows come in. You’ll also hear homeowners call them legal basement windows or basement escape windows. Their most important job is simple: provide a large enough opening for someone to escape through in an emergency.
And that’s where many older basement windows fall short. A window can look reasonably large from inside the room while providing a much smaller opening once it’s actually opened. In those situations, creating a suitable egress opening may mean enlarging the existing foundation opening, installing a different window and, depending on the exterior grade, adding or modifying a window well.
For homeowners renovating a basement, that work can unlock much more than a better window. A properly planned egress installation can be an important part of creating a basement bedroom, making lower-level living space safer or working toward a secondary suite that could eventually generate rental income.
There is an important distinction, though: an egress window alone does not make a basement apartment legal. A secondary dwelling unit has other building, fire, zoning and permitting considerations. The window is one piece of a much larger compliance picture — and it’s worth getting that piece right from the beginning.
That’s why Northline approaches egress differently from a typical window replacement. We look at the existing opening, how the basement will be used and what the project will require before installation begins. From permit planning and preparing the opening through installation and warranty registration, the goal is to give you a basement window that makes sense for the space — and an emergency exit you hopefully never have to use.
Egress Window Requirements
An egress window is ultimately a life-safety feature, so the opening itself matters just as much as the window you see in the wall. Ontario’s Building Code sets specific requirements around how large that opening needs to be, how the window operates and whether someone can actually get through it in an emergency.
When Is an Egress Window Required?
If a floor level contains a bedroom, Ontario’s Building Code generally requires that level to have at least one qualifying exterior window that can be used as an emergency exit, unless a door on the same floor provides direct access to the exterior.
That’s why egress becomes such an important conversation when homeowners start adding basement bedrooms or converting previously unfinished space. The little basement window that has been there for 30 years may be perfectly fine for daylight, but that doesn’t necessarily mean it provides a suitable emergency escape opening.
And an important distinction: the requirement applies to the floor level, not necessarily to every individual bedroom. The layout of the basement and access to the required exit still matter.
How Big Does an Egress Window Need to Be?
Here’s where we can get specific. A qualifying egress window must provide an unobstructed openable area of at least 0.35 m² (approximately 3.77 sq. ft.), with no openable dimension smaller than 380 mm (approximately 15 inches).
It also needs to open from the inside without tools or special knowledge and remain open without someone having to hold or support it.
One thing that catches homeowners off guard is that 15" × 15" does not qualify. Both sides may meet the minimum 15-inch dimension, but the total opening would still be far smaller than the required 0.35 m². With a sliding window, we also have to look at the actual unobstructed opening when the sash is open — not simply the overall dimensions of the window.
How High Can an Egress Window Be From the Basement Floor?
This one gets repeated incorrectly online quite a bit. You’ll often see claims that every basement egress window must have its sill within one meter of the floor, but Ontario’s basement requirements are more nuanced than that.
For basement areas, Ontario’s Building Code guidance recommends that the sill of the required window generally be no more than 1.5 meters above the floor so it can be reached and used in an emergency. If the opening is higher, the accessibility of that window needs additional consideration.
This is one reason we look at the whole basement layout, rather than measuring the window opening alone. An emergency exit only does its job if someone inside can realistically reach and use it.
What If the Window Opens Into a Window Well?
If your basement window sits below grade, the space outside matters too. Where the required egress window opens into a window well, there must be at least 550 mm (about 21.7 inches) of clear space in front of the window.
The way the window opens matters here as well. A sash can’t swing into the well in a way that prevents someone from getting through the required escape space, and any protective cover over the well needs to be openable from inside without a key, tool or special knowledge.
For many Ottawa homes, this means an egress project involves more than simply ordering a larger window. Excavation, the window well, exterior clearance and the new opening all have to work together.
Egress Windows for Basement Bedrooms & Rental Suites
This is where egress windows can become part of a much bigger renovation. Maybe you’re adding a bedroom for a growing family. Maybe you’re finishing an unused basement. Or maybe you’re exploring a secondary dwelling unit that could create rental income from space you already own.
A properly planned egress window can be an important part of making that space safer and meeting the applicable requirements. It can also completely change how a basement feels by bringing in substantially more daylight than the small windows found in many older homes.
Just remember: installing an egress window does not, by itself, make a basement apartment legal. A rental-suite conversion can involve additional building, fire, zoning and permit requirements. Egress is one important piece of that puzzle — and Northline can make sure the window portion of the project is planned properly from the start.
Egress Permits
An egress installation can involve quite a bit more than taking out an old basement window and putting a larger one in its place. When the opening needs to be enlarged or the window sits below grade, there can be permitting, excavation and foundation work to consider before the new window ever goes in.
That’s why Northline approaches these as complete egress projects. The goal is to understand what the basement needs first, plan the work properly and take the project through installation and warranty registration without leaving the homeowner guessing about what happens next.
Assessing Your Existing Basement Window
We start with what you already have. Northline looks at the existing window opening, the interior and exterior conditions, the height from the basement floor and how you intend to use the space.
From there, we can determine whether the existing opening is suitable or whether it needs to be enlarged to accommodate an egress window. We’ll also look at exterior grade and whether excavation or a new window well needs to become part of the project.
It’s an important first step because two basement windows that look almost identical from inside can turn into very different installation projects once you see what’s happening around the foundation.
Preparing & Obtaining the Building Permit
If an Ottawa egress project involves enlarging an existing window opening or creating a new one, a building permit is required before that structural work begins.
The permit process typically involves documenting the proposed opening and project details, preparing the required drawings and submitting the application for City review. The City may request revisions or additional information before issuing the permit, so the actual timeline can vary from project to project.
Northline’s experience with egress installations helps keep the window portion of that process organized from the beginning. We want the opening planned correctly before anybody starts cutting into your foundation — not after.
Excavation, Opening & Egress Window Installation
Once the project is ready to move forward, the real transformation begins. Depending on the existing basement, this can include excavating around the foundation, preparing or enlarging the opening, installing the egress window and adding or modifying the window well where required.
The opening then needs to be properly sealed and weatherproofed, with the exterior conditions around the window taken into consideration. For below-grade installations, drainage and the surrounding window-well area are particularly important — the project still has to deal with Ottawa rain, snow and spring thaw long after the installation crew leaves.
And because this is an emergency escape opening, we’re not simply asking, “Does the new window fit?” It needs to open and function the way the project was designed to.
Inspection, Completion & Warranty Registration
Installation isn't where the process ends. Permitted work may require inspections at the applicable stages of construction, and those inspections are an important part of completing the project properly.
Once the installation and required project steps are complete, the focus turns to final finishing, cleanup and making sure everything operates as intended. Northline can then complete the window’s warranty registration, so you have the proper coverage behind the new installation.
From the first look at that little basement window to the finished egress opening, the idea is pretty simple: do the planning before the cutting starts, install it properly and leave the homeowner with a finished project they can feel confident about.
