Casement window
A casement window is side-hinged and opens outward. Better air-infiltration seal than sliding types, controlled by friction stays under AS 2047.
Ask Chalkline about this →A casement window is a side-hinged sash that opens outward from one vertical edge, swinging on a pair of hinges or friction stays at the jamb. The sash pivots on a vertical axis, unlike an awning window (top-hinged) or a sliding window (no hinge).
Hardware. Operation and hold-open are handled by friction stays: a sliding-pivot arm fixed to the frame at one end, with a slider riding a track on the sash. The friction in the slider holds the sash at any position against wind load without a chain or prop. Latching is via a cam or lever handle on the sash edge that pulls the sash tight against the frame seal. Multipoint locks engage the frame at two or more points for improved security and weather seal.
Sealing advantage. Because the sash closes against a continuous perimeter seal and compresses it, casement windows achieve lower air infiltration figures than sliding windows. Indicative values under AS 2047 testing at 75 Pa: premium casement 0.5 L/s/m² or below; standard sliding window 2.0 to 3.5 L/s/m² (verified 2026-06-11 per air-infiltration corpus data). This makes casements a useful specification tool for thermally critical facades and NatHERS-driven designs.
AS 2047 performance context. Casement windows must comply with AS 2047:2014 covering structural wind load, water penetration resistance, air infiltration, and operating force. The operating-force limit for a hinged sash is approximately 30 to 50 N at the handle (verified per AS 2047 operating-force article 2026-06-11). Products must carry a performance label matched to the site’s AS 4055 wind class; the builder should verify the label on delivery.
Where casements suit. Side-by-side casements can be paired to create a wide opening; a single casement captures cross-breezes by angling the open sash like a scoop. They perform well in coastal and high-wind conditions because the compression seal resists weather infiltration more effectively than brush or fin seals. They are common in premium aluminium, thermally broken aluminium, and uPVC window systems.
Also known as: side-hung window, side-hinged window.
Category: Materials / windows.
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Last updated: 2026-06-11. Verified: 2026-06-11. Quarterly review for currency.