If your uPVC window has started to sag when it is open, refuses to stay put, or has become stiff to close, the part to look at is the friction stay. It is one of those bits of a window nobody thinks about until it stops doing its job. Here is a plain guide to uPVC window hinges, what a friction stay does and when it needs replacing.
A friction stay is the metal hinge that runs along the top or side of a uPVC casement window. It does two jobs at once: it lets the window swing open, and it holds the window steady at whatever angle you leave it. The "friction" in the name is the clue. The stay grips just enough to hold the sash open against the wind without needing a separate catch.
Look at an open casement window and you will see a set of hinged metal arms along the edge, sliding in a channel. Those arms are the friction stay. As the window opens, the arms extend and slide along their track. A built-in resistance in the mechanism is what keeps the window from swinging shut or blowing wide open on a breezy day.
Most stays also space the sash slightly away from the frame as it opens. On many designs this creates an "easy clean" gap, so you can reach the outside of the glass from indoors, which is handy for upstairs windows.
Friction stays come in different sizes and weights. A large or heavy window needs a heavier-duty stay than a small top light, which matters when it comes to replacing one.
A worn stay tends to give itself away in a few familiar ways:
That last point matters. Friction stays are metal, and years of weather can rust or seize them, especially on windows that face the wind and rain. A stiff, gritty hinge is often on its way out.
Sometimes a stay just needs a clean and a little lubrication. Grit and old grease can make a hinge stiff, and a wipe followed by a light spray of the right lubricant can free it up. It is worth trying that first on a sticky but otherwise sound stay.
If the arms are bent, corroded or the friction has worn away so the window will not hold, the stay needs replacing rather than fixing. The good news is that a friction stay is a low-cost part and a fairly quick swap for a fitter, so a sagging window rarely means a new window. As a rough guide in 2026, replacement uPVC window hinges are often in the £15 to £40 range each for parts, plus fitting, though it depends on the size and brand. Treat that as a ballpark, not a quote.
The important bit is matching the replacement to the window. The new stay needs to be the right length and rated for the weight of the sash, or you will be back to the same problem. If you are not sure, our window and door repairs team can identify and fit the correct part.
If the window itself is old, the frame is tired, the seals have gone or the double glazing has misted, it may be worth pricing up a new casement window rather than spending on hinges for a unit near the end of its life. A friction stay is a great value fix on a sound window, but not on one that is failing all round. A good installer will tell you honestly which way makes sense. If you are weighing up a full replacement, our guide to uPVC windows covers the options.
The most likely cause is a worn or failing friction stay, the hinge that grips to hold the window at the angle you set it. Over time the friction wears away, so the window drops shut on its own. Replacing the stay usually cures it.
Yes. If the frame and glass are sound, the friction stay can be replaced on its own without touching the rest of the window. It is a low-cost part and a straightforward job for a fitter, so a sagging window rarely means a full replacement.
As a rough 2026 guide, replacement friction stays are often £15 to £40 each for parts, plus fitting. The exact figure depends on the size and brand of the hinge, so it is best to get a price once someone has seen the window.
First try cleaning out any grit and giving the moving parts a light spray of a suitable lubricant, as old grease and dirt are a common cause of stiffness. If it is still stiff or the arms look bent or corroded, the stay has likely worn out and is best replaced.
Windows past their best rather than just the hinges? Download our latest brochure to see the range, or request a free quote and we will pop out for a look across York and North Yorkshire.