A bedroom in a Québec basement needs a window with a clear opening of at least 0.35 m² (3.77 sq ft) and no side under 380 mm (15 in).34 If the window opens into a window well, keep 760 mm (30 in) free in front of it.4 Enlarging an opening in a Montreal foundation wall needs a city permit.6 Canadian market ranges run about ,500 to ,000 to enlarge an opening and ,500 to ,000 for a new cut with a well.8 These are market ranges, not Factory Direct prices. Your price comes from a written quote after an in-home estimate.
The three numbers for a basement bedroom escape window
Does a basement bedroom need an egress window in Montreal?
Yes. A bedroom needs one outside window or door that opens from the inside without keys, tools or special knowledge.3 The window must also stay open on its own, with no prop.4
Two exceptions exist. The bedroom may have a door that opens straight outside. Or the suite may have sprinklers.35 Most basement bedrooms have neither, so the window does the job.
The rule comes from section 9.9.10.1 of the Québec Construction Code, Chapter I, Building.3 The Régie du bâtiment du Québec (RBQ) publishes that chapter.1 The window is there for emergency escape. Your insurer and a future buyer may also ask about it.5
How big must an egress window be in Québec?
The clear opening must reach 0.35 m², and no dimension may be under 380 mm.3 Clear means the gap you can climb through with the sash open. It is not the frame size.5
Do the math on both sides. At 380 mm wide, the height must reach about 922 mm. A 15 by 36 inch gap looks fine but gives only 0.348 m².
| Clear opening | Area | Result |
|---|---|---|
| 380 × 380 mm (15 × 15 in) | 0.144 m² | Fails |
| 380 × 920 mm (15 × 36.2 in) | 0.3496 m² (just under) | Fails by a hair |
| 15 × 36 in (381 × 914 mm) | 0.348 m² | Fails |
| 380 × 930 mm (15 × 36.6 in) | 0.353 m² | Passes |
| 24 × 24 in (610 × 610 mm) | 0.372 m² | Passes |
| 600 × 600 mm (23.6 × 23.6 in) | 0.360 m² | Passes |
What about the window well?
If the window opens into a window well, leave at least 760 mm in front of it.4 The sash must not cut into that space when it opens.4 A cover over the well must also open from the inside without a key or tool.3
Snow counts. A well that fills with snow no longer works as an exit, so plan to keep it clear in winter.5
Does the rule apply to my existing house?
It applies to work you start. The RBQ ties Chapter I to construction and transformation.12 An industry body for Québec builders says the same escape window is needed in new builds and in a basement you renovate.3
So the case is simple. If you add or finish a basement bedroom, expect the inspector to ask for a window that meets the numbers above. If you only replace a window and keep the room as it is, we found no rule that forces a bigger opening. Ask your borough, because some also set their own rules.5
One edition note. The RBQ says the Code now follows the 2020 national model, in force since April 17, 2025, with a transition period in which work can follow the earlier 2015 edition.12 We read the escape-window text as quoted from the 2015 edition. Ask the permit counter which edition applies to your start date.
Which window type works in a basement: awning, casement, slider or hopper?
Factory Direct sells awning, casement, slider, hung, tilt and turn, and fixed windows in PVC and hybrid.15 Here is how each one fits a basement.
| Type | How it opens | Fit for an escape window |
|---|---|---|
| Casement | Hinged on the side, cranks fully outward | Best fit. The whole sash opens, so a smaller cut meets the rule.8 |
| Awning | Hinged at the top, swings outward. Keeps rain out when open. | Possible if the open gap still reaches the numbers. The sash and its stays stay in the opening, so measure it open.14 |
| Slider | One sash slides sideways | Needs a larger opening, because only part of the window opens.8 |
| Hung (single or double) | Sash slides up or down | Same issue as a slider. Only about half the window opens.8 |
| Hopper | Hinged at the bottom, tilts inward | Factory Direct does not list this type, so we do not cover it here. |
Pick the type from the room. A basement living room or workshop needs light and air, so an awning window is a good choice. A basement bedroom needs the escape numbers, so start with a casement.
Factory Direct does not publish an escape rating for its awning windows.14 Ask the estimator to measure the clear opening with the sash open to its stop.
Do I need a permit to enlarge a basement window in Montreal?
Yes. The City of Montréal says you need a permit to change the size of an existing door or window opening, or to add a new one.6 The page also says a permit is needed to replace windows with the same dimensions.7 Each borough runs its own permit counter.
The fee is $9.80 per $1,000 of work, with a minimum of $167.40 for a house.6 Expect to bring a quote, a certificate of location, a plan with the room sizes and a drawing of the wall with old and new openings.6 A structure plan is needed when the law requires one. A radiation façade calculation is needed if a window grows or is added.6
Cutting a foundation wall is structural work. A Canadian price guide lists $500 to $1,500 when an engineer must review the opening.8 Heritage areas may add rules.6 A licensed contractor should do the work, and you can check any licence on the RBQ site.16
How should a window well and its drainage work?
Water is the main risk below grade. A Québec home inspector says to leave at least 15 cm, ideally 20 cm, between the bottom of the window and the finished ground.11 When the window sits lower than that, or below ground, a window well is needed.11
The same inspector describes a pit about 50 cm deep, lined with galvanized steel, concrete block or poured concrete.11 It is filled with clean 3/4 inch gravel or river stone, up to 20 cm under the window.11 Clear the leaves and debris each season.11
A Canadian price guide adds that a drain under the well costs $500 to $1,500 and that many cities require one.8 Ask who installs the well and the drain. Ask also what the quote assumes about your soil.
Why do basement windows leak or get wet inside?
Three causes show up most. First, the window sits too close to the ground, so melting snow and rain reach the frame.11 Second, the sealing around the frame is poor.8 Third, the well does not drain.11 Hidden water can rot wood framing and grow mould behind a finished wall.11
Wet glass without any leak is usually condensation, which is humid indoor air meeting cold glass. Our guide to window condensation and mould explains how to tell the two apart.
Good sealing and flashing around the opening is part of a correct install. A price guide lists $300 to $1,500 more for extra waterproofing of the wall, depending on the area.8
How much does a basement egress window cost in Montreal?
We found no Montreal-only price published in 2026. These are Canadian, Québec and Ontario ranges, each dated. Prices differ by foundation, window and access.
| Job | HomeStars, Canada, Aug 20268 | Soumissions Sous-Sol, Québec, Dec 202510 | Alpha Windows, Ontario, 20269 |
|---|---|---|---|
| Replace a window in the same opening | $700 – $2,000 | $300 – $800 retrofit, $500 – $1,500 full frame | Not listed |
| Enlarge an opening to egress size | $1,500 – $4,000 | Not listed | $1,800 – $3,500 |
| New cut with window and well | $3,500 – $8,000 | Not listed | $2,500 – $4,500, and $3,000 – $5,500 with well and cover |
| Window well and drain | $150 – $500 for the well, $500 – $1,500 for drain and gravel | Not listed | $400 – $800 for the well, $150 – $300 for a cover |
| Permit fee | $100 – $500 | Not listed | Not listed |
HomeStars puts the typical Canadian egress job at $2,500 to $8,000, with most homeowners near $4,500.8 The Québec site gives example totals of $4,450 to $5,562 for three sliding PVC basement windows.10 Montréal adds its own permit fee: $9.80 per $1,000 of work, $167.40 at least.6
Compare quotes line by line. Ask what is in the number: window, concrete cut, lintel, well, drain, permit, finishing and haul-away. For more on pricing, see our window replacement cost guide.
Does Rénoclimat pay for basement windows?
Rénoclimat gives $300 per replaced window, up to $4,500 for a house and $6,000 for a duplex, triplex or multi-unit building, for new files since October 1, 2026.12
The Québec.ca pages we read do not exclude basement windows. They require that the window go into an existing rough opening in a wall.13 A bigger opening cut in the foundation is not a replacement in an existing opening, so do not count on $300 for the enlarged part. Your Rénoclimat advisor confirms what qualifies.
Québec.ca also lists a separate path for homes in flood zones that includes sealing openings, with its own amounts.12 Our Rénoclimat checklist for windows and doors lists the steps. Confirm every term on Québec.ca.
FAQ
What is the minimum egress window size in Québec?
A clear opening of at least 0.35 m² (3.77 sq ft) with no dimension under 380 mm (15 in).3 Both tests apply.
Can an awning window be an egress window?
Yes, if the open gap still meets 0.35 m² and 380 mm. The sash and its stays stay in the opening, so measure it fully open.14 A casement usually gives more clear area for the same hole.
Do sliding windows work as bedroom escape windows?
They can, but only part of the window opens. That is why a slider needs a larger opening than a casement for the same clear area.8
Does a window well need a cover?
No cover is required by the rule we read. If you add one, it must open from the inside without a key, tool or special knowledge.3
Do I need a permit to enlarge a basement window in Montreal?
Yes. A permit is needed to change an opening’s size or add one, and the fee starts at $167.40 for a house.6 Your borough counter confirms the file.
How do I check my contractor?
Look up the licence number on the RBQ site before work starts.16 Factory Direct’s RBQ licence is 5735-2130-01.
Want your window measured? Book a free in-home estimate with Factory Direct Montreal. We measure every opening and send a written quote. If the opening must grow, ask what the quote covers and who files the permit. Factory Direct has completed 9,200+ projects across Greater Montréal over 35+ years (RBQ 5735-2130-01).
Sources
- Gouvernement du Québec, Régie du bâtiment du Québec, Chapitre Bâtiment du Code de construction du Québec incluant le CNB 2020 (French), in force April 17, 2025: www.rbq.gouv.qc.ca.
- Gouvernement du Québec, Régie du bâtiment du Québec, Chapitre Bâtiment du Code de construction du Québec en vigueur de 2021 à 2025 (French), based on the 2015 national model, read November 12, 2026: www.rbq.gouv.qc.ca.
- APCHQ (Québec builders association), Coincé dans la fenêtre du sous-sol (French), September 4, 2024. It restates the Code text of section 9.9.10.1, 2015 edition, and is not the Code itself: www.apchq.com.
- APCHQ, Dégagement à l’avant d’une fenêtre de chambre au sous-sol (French), cites article 9.9.10.1 (3) and (4) of the 2015 Code, read November 12, 2026: www.apchq.com.
- Vaillancourt Windows and Doors, Egress: requirements and dimensions for a bedroom window, published October 10, 2023: www.vaillancourt.ca.
- Ville de Montréal, Ajouter des portes et fenêtres ou les remplacer par des modèles de différentes dimensions (French), updated January 31, 2026: montreal.ca.
- Ville de Montréal, Remplacer des portes et des fenêtres par des modèles de mêmes dimensions (French), read November 12, 2026: montreal.ca.
- HomeStars, How Much Does a Basement Egress Window Cost in Canada?, updated August 21, 2026: r.homestars.com.
- Alpha Windows (Ontario), Egress window cost in Ontario 2026, published June 9 and updated November 1, 2026 (Ontario prices): www.alpha-windows.ca.
- Soumissions Sous-Sol, Installation fenêtre sous-sol : prix au Québec 2026 (French), modified December 31, 2025: soumissionssous-sol.ca.
- Inspecteur D (Québec home inspector), Ces fenêtres de sous-sol trop près du sol (French), October 16, 2015, with diagrams credited to CMHC. Older than 2020, so we use it only for site drainage practice: inspecteurd.com.
- Gouvernement du Québec, Rénoclimat, Nouveautés en vigueur depuis le 1er octobre 2026 (French), updated October 13, 2026: www.quebec.ca.
- Gouvernement du Québec, Remplacer des portes et des fenêtres (French), updated October 13, 2026: www.quebec.ca.
- Factory Direct Montreal, Awning windows (read November 12, 2026): www.factorydirectmontreal.ca.
- Factory Direct Montreal, Windows (read November 12, 2026): www.factorydirectmontreal.ca.
- Régie du bâtiment du Québec, Check a contractor’s licence: www.rbq.gouv.qc.ca.
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