Window sash
A window sash is the framed, openable part that holds the glass. Sash types, sash vs frame, and why sash weight matters for hardware compliance.
Ask Chalkline about this →A window sash is the framed, openable unit that holds the glazing inside a window assembly. It is distinct from the outer frame (the fixed surround attached to the wall), which stays in place. The sash moves; the frame does not.
On most Australian residential windows the sash and frame are aluminium extrusions. On heritage and period-style builds the sash may be timber, uPVC, or steel.
Sash by window type
The way a sash moves determines the window type and the hardware required.
| Window type | How the sash moves | Typical AU use |
|---|---|---|
| Sliding (horizontal) | Sash slides along a horizontal track, usually one fixed and one movable | Dominant in volume residential |
| Double-hung (vertical) | Two sashes in the same frame slide vertically, each counterbalanced | Period-style homes, renovation |
| Casement | Single sash hinged at one side, swings outward | Kitchens, studies, ventilation focus |
| Awning | Sash hinged at the top, bottom swings outward | Wet areas, clerestory, stay-open in rain |
A fixed light is not a sash: it is glazing set directly into the frame with no movable component.
Sash weight and hardware
Sash weight affects two things: operating force compliance under AS 2047:2014, and the hardware selection.
A heavier sash needs stiffer friction stays (casement and awning), or stronger sash balances (double-hung), to stay open without drifting or slamming. A sash that is too heavy for its hardware will fail the AS 2047 operating-force test. The performance label on each window unit records the rated operating force for the product as tested.
On double-hung windows, sash balances (spring or cord-and-weight) counterbalance each sash so it stays at any height. A failed balance causes the sash to drop or jam. See window hardware for balance types.
Sash seals and weatherproofing
The joint between sash and frame is where weatherproofing pressure is applied. AS 2047:2014 tests each window unit’s water penetration resistance with the sash closed; a deformed or warped sash breaks the seal and fails the test. For the aluminium window installation procedure see aluminium windows.
Also known as: sash window, window sash frame, glazed sash.
Category: Windows and doors.
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Last updated: 2026-06-11. Verified: 2026-06-11. Quarterly review for currency.