A casement window is a window hinged on one vertical side that swings outward — or occasionally inward — on a crank mechanism. It opens like a door, giving you full control over ventilation and creating a tight, weatherproof seal when closed. Casement windows are one of the most popular window styles in Canadian homes because they perform well in cold climates and meet ENERGY STAR™ certified standards more easily than many other designs.
If you’re comparing window types for a replacement project, casement windows consistently come up as a top performer for energy efficiency, security, and clean modern looks. Here’s everything you need to know.
How a Casement Window Works
The operating mechanism is simple. A handle or crank turns a multipoint locking system that simultaneously pulls the sash tightly against the frame. When you want fresh air, you rotate the crank and the sash swings out — typically 90 degrees — on its hinges.
Because the sash presses flush against the weatherstripping all the way around when locked, there are very few air gaps. This compression seal is the main reason casement windows tend to outperform sliding or single-hung windows on airtightness.
Most casements open to the left or the right depending on hinge placement. Some are available as inward-opening tilt-and-turn units, which bring added versatility — you can learn more about tilt-and-turn windows if that style interests you.
Types of Casement Windows
Not all casement windows are the same. Here are the common configurations you’ll find:
- Single casement – One sash hinged on either the left or right side. The most common type for individual openings.
- Double casement – Two sashes hinged on opposite sides of the same frame, opening outward from the centre like French doors.
- Push-out casement – Opens by pushing rather than cranking. Common in European designs.
- In-swing casement – Hinged to open inward. Rare in Canadian residential builds but useful where exterior clearance is limited.
- Picture + casement combination – A fixed centre lite flanked by operable casement units on either side.
You can also look at the different casement window types to see which configuration works best for your space.
From Our Showroom: Best Sellers in the GTA
Casement Window vs Other Common Styles
| Feature | Casement | Double-Hung | Slider |
| Airtightness | Excellent | Moderate | Moderate |
| Ventilation | Full sash opening | 50% of sash | 50% of sash |
| Egress compliance | Usually yes | Depends on size | Depends on size |
| Cleaning access | Easy (exterior surface reachable from inside) | Easy with tilt-in sash | Moderate |
| Energy efficiency | High | Moderate | Moderate |
If you’re weighing casement against awning windows, there’s a full breakdown in our casement vs awning window comparison.
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Pros and Cons of Casement Windows
Advantages
- Full ventilation — the entire sash opens, unlike sliders that only open halfway
- Superior air seal due to compression weatherstripping on all four sides
- Easier to clean — you can reach the exterior glass from inside
- Good for egress in bedrooms and basement applications (check Ontario Building Code minimums for your municipality)
- Works well with ENERGY STAR™ certified glazing packages — Low-E coatings, argon gas fills, and warm-edge spacers all integrate cleanly into the casement design
Disadvantages
- The outward swing can conflict with decks, patios, or walkways
- Screens go on the interior side, which some people find less convenient
- Crank mechanisms can wear over time and may need servicing
- Not ideal for very wide single openings — double casements or sliders are better there
Casement Window Sizes
Standard casement windows range from roughly 14″ to 36″ wide and 24″ to 72″ tall, though custom sizes are common in replacement projects. The rough opening needs to account for the frame and shimming space — typically an extra ¾” on each side and at the head.
For bedroom egress, Ontario Building Code requires a minimum unobstructed opening of 0.35 m² with no dimension less than 380 mm. Most standard casements comfortably meet this requirement. If you’re measuring for a replacement, our guide on replacement casement windows walks through the sizing steps.
Casement Window Costs in Canada (2026)
Pricing varies based on size, glazing package, and installation complexity. Here’s a general guide for vinyl casement windows in the GTA market:
| Window Type | Supply Only (CAD) | Installed (CAD) |
| Standard single casement (double-glazed) | $400–$700 | $700–$1,100 |
| Standard single casement (triple-glazed) | $550–$900 | $900–$1,400 |
| Double casement unit | $800–$1,400 | $1,200–$1,900 |
| Bay/bow with casement flankers | $2,500–$5,000+ | $3,500–$7,000+ |
Triple-glazed units typically cost 20–30% more than double-glazed equivalents but deliver noticeably lower U-factors — around 1.0–1.3 W/m²K versus 1.6–1.9 W/m²K for double glazing. In a GTA winter, that difference matters.
Expert Tip — Mireille Fontaine, Certified Passive House Consultant, Hamilton ON: “Casement windows are my first recommendation for clients who want to improve airtightness without a full envelope overhaul. The compression seal on a quality vinyl casement, especially with triple glazing and a warm-edge spacer, can bring infiltration rates down dramatically compared to a worn sliding or double-hung unit. Don’t just look at the U-factor — ask for the whole-window SHGC and the air leakage rating under NAFS testing.”
Casement Windows and Energy Efficiency
The compression seal is the key thermal advantage. When the multipoint lock engages, the sash is pulled tight against the gasket on all four sides — there’s no sliding track for air to leak through.
This makes casement windows a natural fit for ENERGY STAR™ certified packages. To earn ENERGY STAR™ certification in Ontario’s climate zone, a window must meet minimum U-factor and SHGC thresholds set by Natural Resources Canada. Most quality vinyl casements with Low-E 272 or 366 coatings and argon fills comfortably meet these thresholds.
For homeowners in Mississauga, Brampton, or Vaughan who are replacing older aluminium or wood-frame windows, upgrading to ENERGY STAR™ certified vinyl casements is one of the higher-impact changes you can make to a home’s thermal envelope.
Expert Tip — David Krawchuk, Building Science Technologist, Toronto ON: “A lot of homeowners focus on the glass spec and overlook the frame. In vinyl casement windows, the number of frame chambers matters — a five-chamber or seven-chamber uPVC profile breaks up thermal bridging far better than a basic two-chamber extrusion. Ask your supplier for the whole-unit U-factor tested to CSA A440, not just the centre-of-glass number.”
Are Casement Windows Right for Your Home?
Casement windows work well in most situations. They’re especially suited to:
- Living rooms and bedrooms where ventilation and energy efficiency both matter
- Kitchen windows above counters or sinks (the crank is easy to operate without leaning far)
- Basement egress windows, where the full-open sash helps meet code dimensions
- Contemporary or modern home styles where slim frames and large glass areas are a priority
They’re less ideal where the exterior swing would be blocked, or for very large single openings where a picture window or bay window replacement may be a better architectural fit.
If you’re replacing windows in Scarborough, Brampton, Vaughan, or elsewhere in the GTA, contact TotalSeal for a no-obligation in-home quote. TotalSeal manufactures and installs its own vinyl window systems in-house, which keeps quality consistent from production through to installation.
FAQ
What is the difference between a casement window and a regular window?
“Regular window” usually means a double-hung or sliding unit. A casement window hinges on the side and swings outward on a crank, creating a tighter compression seal and better ventilation than a sliding or hung sash.
Are casement windows more energy efficient than double-hung windows?
Generally, yes. The compression weatherstripping on a casement seals all four sides when locked, reducing air infiltration more effectively than the sliding sash tracks on a double-hung window. This makes them easier to certify to ENERGY STAR™ standards.
Can casement windows be used for bedroom egress in Ontario?
Yes, in most cases. Ontario Building Code requires a minimum unobstructed opening of 0.35 m² with no dimension below 380 mm. Most standard casement widths and heights meet this requirement without needing an oversized unit.
How long do vinyl casement windows last?
Quality vinyl casement windows typically last 25–40 years with minimal maintenance. The uPVC frame won’t rot, warp, or need painting. Crank mechanisms and weatherstripping may need servicing or replacement after 15–20 years of heavy use.
What is a typical casement window installation cost in Ontario?
Installed costs in the GTA typically range from $700 to $1,400 per window for a standard vinyl casement, depending on size and glazing package. Triple-glazed units sit at the higher end. Full-home replacement projects are usually quoted at a package rate.
