Whether you are planning to convert your basement into a bedroom, a legal rental, or an in-law, there will be one thing you will hear about in all discussions with your contractor, building inspector and permits application – the egress window.
Turn out right and your basement is a legal and safe living room that can be inspected. Do not get it wrong, or you will risk a failed inspection, reworking costs, and will essentially be renting a bedroom section of the home inaccessible under the law. In the best of all worlds, a wrong (or no) window means a life is jeopardized.
This guide addresses what the Building Code in Ontario 2024 requires, the importance of egress windows, what kind of windows work, what a compliant window egress well looks like and the window installation process in Toronto and the GTA.
What Is an Egress Window?
An egress window is a window that is large, accessible and properly located to serve as an emergency exit. The term egress just means exit.
In a basement egress window is a window to provide a second way out of a building to a person sleeping in the basement when a fire has occurred on the main floor, and they cannot get out the stairs. If a window doesn’t open then that’s a second chance that doesn’t exist.
One of the most valuable house remodeling projects a Canadian homeowner can undertake is a finished basement bedroom. However, this figure is erased once a building inspector comes across an unfit window. It’s simply a matter of life and death beyond the inspection – someone who turns off on the basement stairs will need some other way out of the house if the fire has blocked the interior stairs, other than improvising and praying.
Ontario Building Code: 2024 Update – What Changed and When
Section 9.9.10 of the Ontario Building Code (OBC) regulates the rules of egress in Ontario. It’s a big update to the 2024 Ontario Building Code (OBC) released on 1 January 2025, with the province adopting its own Building Code and reducing more than 1,700 differences between Ontario and the National Building Code requirements. On 1 April 2025 all building permit applications in Ontario will take the form of the new 2024 Building Code.
For any homeowner looking to renovate their basement, this is important for all homes in Toronto, Vaughan, Mississauga, and the GTA region. For permit applications received after April 1, 2025, the 2024 OBC is in full effect for your project.
Who Needs a Basement Egress Window?
All bedrooms in a house should have at least one window that opens directly out to the outside – an egress window. This can be used for the bedrooms on any level, but it’s most often a consideration in renovating a basement.
A compliant basement egress window must be used when:
- You want to install a Master Bedroom in the basement
- Constructing a legal secondary suite or basement apartment
- Now you’re designing an in-law suite that includes a sleeping space
- A rec room or den is available in your finished basement where a bed is a viable option
Only for a basement having a walkout door that provides direct access to grade at exterior level – this is a special condition. If that door is not the main exit, then it can be used as the second, provided the bedroom exit is not through a furnace room or other hazard area.
Most Ontario basements have an egress window, as it is absolutely essential for basements that can only be entered from the inside stairs and have windows at or near the ground level.
The Exact Dimensions: What Ontario Building Code Requires
The dimensions are clearly specified in the Ontario Building Code in section 9.9.10 in plain millimetres and metres. Inspectors measure to the millimetre – close is not good enough.
These are the criteria you must adhere to to make sure your egress window fits the required open area:
Minimum clear opening area: 0.35 m² (3.77 sq. ft.)
Minimum dimension: No single dimension of the opening – neither height nor width – can be less than 380 mm (15 inches).
Maximum sill height: Sill height should not exceed 1.5 metres (59 inches or 4.9 feet) above the floor, the height of the lowest part of the window opening (the sill). This to make sure you are able to get out if the average person got in. It’s significantly higher than the OBC allowances for above-grade bedrooms where the ceiling height is 1,000 mm with the windows above 2,000 mm.
Operability: Must be able to open the window from the inside without any tools or special knowledge. No keys, no special latches, no tools – and no one needs to be familiar with the procedure to use the simple crank or latch under panic situations.
One measurement trap to avoid: If you use a window that measures 380 mm × 380 mm, you have 0.144 m² – less than half of what you need. The minimum dimension and the minimum area need to be met simultaneously. In reality a typical code-compliant egress window is approximately 15″ X 35″ or 20″ X 24″ in clear opening.
Clear opening is the real unobstructed opening when the window is opened fully, not the glass opening, not the frame, nor the rough opening. The clear opening is inspected by the inspectors. This is the number that determines it.
Which Window Types Work for Basement Egress?
Not every window is the same as far as meeting egress requirements. The window type can have a significant impact on the size of the clear opening you have – and the size of rough opening you have to cut.
Casement Windows – The Best Choice
Swings completely outward on one side. Offers the biggest clear opening for the size of frame – a 24″ x 36” casement provides almost the entire opening. Easy to use crank handle (no special tools). Proven as the standard solution for basement egress in Ontario.
Casement windows are the best way to create a compliant egress opening in your foundation with the least amount of rough opening. Reduced concrete cutting results in reduced costs of installation and reduced disruption of structures.
Slider Windows – The Worst Choice
The worst windows to use are slider windows. Excluding the cost of the window size, to obtain a good opening of 3.77 sq. ft., the window must be bigger than 7.5 sq. ft. (for example, a window that measures 48″ × 48″) which is often not possible in a basement. Not only does only one half of the window open at a single time, but to get the same clear opening as a casement you have to cut through double the amount of concrete – more excavation, and more cost.
Awning Windows – Not Suitable
Awning windows (hinges on the top) are usually not appropriate for egress. Most building officials will not accept them and the opening geometry makes them extremely difficult for a person to climb into, no matter how wide the opening area is.
In-Swing Casement – Works with Conditions
If the room is large enough in front of the window for the sash to open and for one person to move through, an in-swing casement can be eligible. This is a style that is less popular, but can be achieved in certain set-ups in basements.
Window Wells: The Part Most Homeowners Get Wrong
If your window egress is located below grade (most basement windows are in Ontario), then you will also need window wells. This windowed construction features its own set of enforceable requirements under the OBC and the window well is a component of the escape route.
The window well must have enough room for a person to stand in front of the open window and get off. Not a pretty box to plant in. It is an emergency evacuation way.
Minimum clearance: At least 550 mm (1’10”) of clearance in front of the window. If a window sash opens out onto a window well, it shall not open so as to prevent escape in an emergency.
Ladder requirement: It must have a permanent ladder or steps installed (not a loose piece of wood leaning against the wall) if the depth of the well is greater than 600 mm (24 inches) from grade to the bottom. A fixed point for climbing out of which a person cannot stray.
Drainage: The well should be adequately drained – at least with a gravel bottom, and in many instances there should be a weeping system or sump connected to a drainage tile. A window well that can fill with water when the spring thaws or during a torrential rain is not only a code issue, it’s a flooded basement waiting to bring home the bacon.
Window well covers: If a cover is installed over the well, commonly to keep debris and water from getting trapped in the window well, it is required to be easily openable from the inside with no tools or special knowledge. Locking covers are an automatic inspection failure.
One of the most frequent issues with failed egress inspections throughout Toronto and the GTA is the window well. A properly sized window put in an undersized well, a well that has never been drained or a well that has not been covered will have no effect.
Do You Need a Permit for Egress Window Installation?
Yes. Every time. No exceptions.
Opening new spaces or adding a new basement bedroom requires a permit. These applications will result in a full review for code compliance. This step is a serious matter to be taken or not. There are several steps involved in the inspection process. Inspectors review the end setup, waterproofing and structural framing.
Not fulfilling the permit requirement doesn’t eliminate the requirement. It makes the resale issue so much bigger – when the buyer’s lawyer or home inspector discovers that the basement bedroom wasn’t permitted, it will be disclosed, remediated, or cause a price drop. That isn’t a trivial risk for Toronto’s real estate market.
Permit requirements exist for egress window installations in all municipalities across the GTA, including Toronto, Mississauga, Vaughan, Scarborough, North York, Markham and Richmond Hill. Your contractor should be removing the permit, not recommending you do not obtain one.
What Does Basement Egress Window Installation Actually Involve?
Adding a compliant egress window to an existing Ontario basement is a structural job and not the same as buying and replacing a window.
A bare-bones casement basement window costs $400 to $1200, yet it’s the work around the window where budgets grow out of control. Typically $4,000 to $10,000 per opening is added to foundation cutting, structural lintels, a properly drained window well and waterproofing. In older homes in Toronto an incomplete roof installation may cost more than $15,000 depending on the inclusion of deep wells with ladders, sump connections and finish work.
Installing a typical GTA home can take place through the following:
Foundation cutting – The new hole is sawed or core drilled through the poured concrete or block foundation wall. This is no DIY job. Removal of a 36-inch opening in a poured concrete or block foundation will compromise a load path and require replacement. If a homeowner does the opening they will run the risk of cracking their walls within a year.
Structural lintel – A steel or engineered beam is placed above the new opening to support the weight that was previously supported by the removed concrete beam. This is a requirement on all projects.
Waterproofing –Application of a rough opening, frame and surrounding foundation to prevent water penetration. Key in the freeze-thaw Ontario climate conditions as soon as water damage and mould develops in one or two seasons with improper sealing.
Window well excavation and drainage – Excavated, graveled, or tiled window wells are excavated and filled with gravel or tiled, with a well liner attached to the foundation.
Window installation – Egress compliant casement installed, leveled, insulated and sealed.
Inspection – Municipality conducts on framing, after waterproofing, and at final completion.
Egress Windows and Legal Basement Apartments in Toronto
Where the intent is a legal secondary suite (a residential basement apartment that the municipality allows to be rented out), egress windows are but one element of a myriad of compliance requirements including fire separation between units, separate smoke and CO alarms, minimum ceiling heights, and independent utility metering, to name a few.
Housing policy makers in Toronto have embraced secondary suites, while Ontario’s housing legislation has eased some restrictions on accessory dwelling units in town. However, egress window compliance is a difficult and unchangeable requirement for all legal suites. Whether your lease dictates otherwise, the house you are renting out doesn’t have a legal outlet into the basement, and it will not be a permitted rental property.
Why Professional Installation Matters
Installing egress windows is a mix of structural design, waterproofing, building code adherence and permit coordination. The implications of doing it wrong – poor inspection, water damage, structural issues, and legal non-conformance, are costly and consequential.
Milano Windows & Doors is an Energy Star certified casement window company that offers windows that meet egress requirements in Ontario throughout Toronto, North York, Scarborough, Etobicoke, Vaughan, Mississauga, Markham and the GTA. All egress is fully permitted, inspected and installed in accordance with the 2024 Ontario Building Code for any installation we work on.
Frequently Asked Questions: Egress Windows
What is an egress window?
An egress window is a window that is sufficiently large, conveniently located and easy to open to provide a non-constructed means of egress in case of fire. In the province of Ontario, egress windows must be installed in each bedroom located below grade, so that if a fire occurs and forces the occupants to stay in, there’s a second way out.
What are the minimum egress window dimensions in Ontario?
In the Ontario Building Code 2024, the minimum requirement for a basement egress window is to have a clear opening of at least 0.35 m² (3.77 sq. ft.) with a minimum dimension of 380 mm (15 inches). The height of the window sill should be no more than 1.5 m (59 inches) above the level of the finished floor. These are the actual opening dimensions, not the frame or glass dimensions.
Do I need an egress window if my basement has a walkout door?
Only when the walkout door opens directly to grade and the pathway from the bedroom to the walkout door passes a furnace room or storage area, or other hazard area. If there is a walkout, then no sleeping space is required to have an egress window; however, if there is no walkout, an egress window is required for any sleeping space in most Ontario basements.
What is the best window type for basement egress in Ontario?
A casement window is the best choice. Hinged on one side, it swings almost 180 degrees, allowing for almost the full frame area to be accessible. This translates to code compliant with a smaller rough opening than any other window type – less concrete cutting, less cost and less mess.
Do egress windows require a window well?
Yes, in most cases. Basement egress windows below grade must have a window well with a minimum of 550 mm of clearance in front of the fully open window. A permanent ladder or steps must be permanently attached to the well if the well is deeper than 600 mm. The well must also be properly drained.
Do I need a permit for egress window installation in Ontario?
Yes. New openings in foundation walls (and new additions of bedrooms to the basement) will require a permit. A series of inspections by your municipality will take place. Lack of unpermitted egress installations cause issues at resale and leave homeowners with legal liability.
How much does basement egress window installation cost in Ontario?
The window usually ranges in price from $400 to $1,200. Typical costs for total installation of the concrete cutting, structural lintel, window well, drainage, waterproofing and permits range from $4,000 to $10,000 per opening. For older Toronto homes that have window wells that are several feet deep, the cost of a complex project can greatly surpass $15,000.
Can I install a basement egress window myself?
While technically a window could be installed by the homeowner, any cutting through a foundation wall, installing a structural lintel and waterproofing the window assembly should only be done by licensed professionals. When structures are incorrectly built, it can lead to foundation cracking. If the waterproofing is not done properly, water intrusion will occur. In most municipalities there’s also a need for a licensed contractor to perform permit work.
Does a finished basement rec room (no bedroom) need an egress window?
In other words, if there is no sleeping area – no bedroom, no den in which a bed could be placed – an egress window is not strictly required for the rec room itself, if the basement has another way of exit. But if any one sleeps there even from time to time, compliance is necessary. Many contractors suggest installing a compliant window just in case because it provides the flexibility in the future and it enhances the usable and rentable value of the space a great deal.
How does egress window installation affect home resale value in the GTA?
If the house has a compliance/permitted egress window, it can make a big difference in resale value as this allows you to get that legal basement bedroom or rental room. Mortgage helpers – Toronto and GTA real estate buyers are actively looking for legal second floor apartments. Depending on the neighbourhood, the valuation of the home can increase by $30,000 – $80,000 or more with the inclusion of a permitted, compliant, basement bedroom. A window that does not meet code or a basement bedroom that is not permitted poses liability and negotiating issues at closing.