The hardware that makes a window work.
Handles, hinges, locking points, keepers and limiters: what each part does, and what to ask for by name.
Vistaza Engineering · May 18, 2023 · Updated Sep 8, 2026 · 5 min read
On a casement window, one handle drives everything. Turning it moves a metal strip that runs around the edge of the sash. Locking points on that strip slide behind keepers on the frame and pull the sash onto its gasket. The hinges carry the weight. A limiter sets how far the sash can open. When a window "does not close properly", the cause is nearly always one of these parts, and it usually needs adjusting, not replacing.
Handles.
The handle is a lever on a square spindle. Its position tells you what the window will do: locked or open. A lever handle works with one hand and needs no tight grip, which matters in accessible rooms.
- Window handles. Vistaza handles carry the Vistaza V and come in white, silver and black.
- Locking handles. A key or button in the handle stops it turning. They are used in common areas and where children can reach the window.
- Door handles. A terrace door has a handle set with an inside and an outside plate, and a cylinder lock. A half-cylinder with a thumbturn locks from the room side without a key.
- Flush handles. A sliding panel that passes in front of a fixed one needs a handle that sits flat in the face of the panel.
Hinges: exposed and concealed.
An exposed hinge sits on the room-side face of the window under a snap-on cover. A concealed hinge sits in the gap between the sash and the frame. With the window shut, it cannot be seen at all.
| Exposed | Concealed | |
|---|---|---|
| With the window shut | Hinge covers show at two corners | Nothing shows |
| Opening angle | Wide. The sash can fold back towards the wall | Smaller. The hinge geometry sets it |
| Sash weight | Each hinge model has a weight limit | The same. Check it for heavy glass |
| Cleaning and painting | Covers gather dust and can be knocked off or lost | Nothing on the face to clean around |
| Adjustment | Hex key, with the covers off | Hex key, with the sash open |
Neither is wrong. Concealed hinges give clean lines and leave nothing on show. Exposed hinges suit a sash that has to open right back, and a missing cover is a quick and cheap repair. Either way, the weight of the glass decides the hinge. A laminated acoustic triple weighs far more than a standard double, and the hinge has to be rated for it.
The Vi6 comes with concealed hinges. The Vi5 comes with standard, visible hinges under a cover. Hinge covers, window hinges and the scissor stay are all in the Vistaza parts list. The scissor stay is the arm at the head of the sash. It acts as the upper hinge when the sash swings.
Locking points and keepers.
A locking point is a small cam on the moving strip, often shaped like a mushroom. A keeper is the plate on the frame that the cam slides behind. A large sash has more of them, spaced around all four sides. That is what keeps the corners of a big sash tight against wind pressure, and it is a large part of why compression-seal windows test well for air and water.
- Anti-pry keepers. These are shaped to trap the head of the cam, so that the sash cannot be levered out of the frame from outside.
- Compression is adjustable. On most hardware the cam is eccentric. Turning it with a hex key or the window adjustment tool changes how hard the sash presses on the gasket. More compression gives a tighter seal and a stiffer handle. Set it as tight as the seal needs and no tighter.
Limiters.
A vent limiter holds the sash to a small gap, usually four inches. On a Vistaza window it sits at the lock side of the sash, where it is easy to reach, and it comes on every operable window as standard, so it is already on the shop drawings. When it applies and how to specify it are covered in what the four-inch rule means.
Gaskets.
Gaskets are not hardware in the strict sense, but they wear like hardware and they are replaceable. One gasket seals the sash to the frame. Another holds the glass. A gasket that has been pressed flat, torn or painted over lets in air and noise at that spot.
When a window plays up.
| What you see | Likely cause | What to do |
|---|---|---|
| The sash drags on the frame at the lower corner on the handle side | The sash has dropped on its hinges | Adjust the hinges with a hex key |
| The handle is stiff | Too much compression, or a dropped sash so that the cams meet the keepers badly | Adjust the hinges first, then the cams |
| A draft at one corner | Low compression at the nearest locking point, or a flattened gasket | Adjust the cam. Replace the gasket if it is damaged |
| The handle turns but nothing locks | The handle or the gear behind it has failed | Replace the handle. If that does not cure it, ask for service |
Most adjustments need only hex keys in 3, 4 and 5 mm (3/16″) and the window adjustment tool for the series. Some fasteners take a security Torx bit. Adjustment is a job for building staff or a service technician, not for residents.
Most windows that will not close need a hex key, not a new part.
Ask for it by name.
When you order a part, give four things:
- The name of the part, as it appears in the parts catalog.
- The series: Vi6 or Vi5, terrace door or sliding door.
- The frame color, inside and outside.
- The opening number from the sticker inside the frame, if you can read it. It identifies the exact unit.
The parts catalog is on the service and parts page. The hinges and the steel behind them are shown on the Vi6 page.