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Why Won't My uPVC Window Close Properly?

For a side-hung or top-hung uPVC window that catches the frame, stops short of closing, needs lifting or pushing to shut, or no longer lines up with the locking keeps.

By Home ManualReviewed 31 August 2026Safety level S1UK guidance
Quick answer

What this usually means

A uPVC window that used to close normally but now catches or stops short is often an alignment or hinge problem rather than a failed frame. Friction-stay hinges wear, screws can loosen, moving parts can become dry or dirty, and the sash can drop slightly until the locking cams no longer meet the frame correctly. Hot weather can also make a tight-fitting window temporarily harder to close. Do not force the handle if the sash is visibly out of line, because that can damage the locking mechanism as well.

Likely causes

What may be causing this

1

A friction-stay hinge has worn or dropped

Clues: The sash sits slightly lower on one side, catches the frame or only closes if you lift it gently.

What to do: The hinge may need adjustment or replacement. Friction stays should be matched to the window size, opening style and weight.

2

The hinge or locking hardware is dry, dirty or obstructed

Clues: The window has gradually become stiff, there is grit in the mechanism, or movement improves slightly after careful cleaning.

What to do: Clean accessible hardware and use only the light lubricant recommended by the window manufacturer. Do not pack grease into plastic hinge parts.

3

The sash and locking keeps are out of alignment

Clues: The window physically reaches the frame but the handle will not complete its turn, or locking cams hit the keeps instead of entering them.

What to do: Do not force the handle. The sash, hinge or keeps need realignment so the locking points meet correctly.

4

Temperature movement is exposing an already tight fit

Clues: The problem is much worse on very hot days and eases when the temperature drops.

What to do: Small thermal movement can make a marginal alignment problem more obvious. Persistent catching still deserves adjustment rather than repeated force.

Diagnose the pattern

How to check what is happening

Close the window slowly and watch where it first touches
One corner or edge contacts the frame before the rest

The sash is likely out of square or a hinge has dropped.

Look at the gap around the sash
The gap is noticeably narrower on one side or at one corner

Alignment has shifted rather than the problem being only the handle.

Move the handle only when the sash is naturally seated
The handle becomes stiff before the window is fully closed

The locking cams may be meeting the keeps incorrectly; forcing the handle risks gearbox damage.

Compare hot and cooler parts of the day
The window is much tighter in hot weather

Thermal movement may be contributing, but worn hinges or tight alignment can still be the underlying issue.

DIY decision

Can you fix this yourself?

Cleaning accessible tracks and lubricating approved moving metal parts is straightforward. Minor friction adjustments can also be a user task on some windows. Replacing hinges, supporting the sash, realigning locking hardware or working at height is better left to a window repair specialist.

You'll usually need:
  • Soft cloth
  • Light machine oil if approved by the window manufacturer
  • Screwdriver only for manufacturer-approved adjustments
  • Torch
Step by step

What you can safely try

  1. 1

    Find where the sash is catching

    Close the window slowly without forcing it and watch the gap around the frame. Note the first corner or edge that touches; that tells you far more than repeatedly pushing harder.

  2. 2

    Clean accessible hinges and locking points

    Remove dust and grit with a soft cloth. If the manufacturer recommends lubrication, apply a small amount of light machine oil to the metal moving parts only.

  3. 3

    Do not use the handle as a lever

    If the sash is not seated correctly, forcing the handle can damage the espagnolette gearbox or locking cams. Get the alignment right first.

  4. 4

    See whether heat is making a marginal fit worse

    If the window only sticks during very hot weather, test it again when conditions are cooler. If it still catches or needs lifting, the hinge/alignment issue should be repaired.

  5. 5

    Have worn hinges or alignment corrected

    A window repair specialist can support the sash, replace matching friction stays and reset the locking alignment without replacing the complete window if the frame is otherwise sound.

Stop conditions

Call a window fitter if…

  • The sash feels loose, drops suddenly or is difficult to support safely.
  • The window is above ground level and repair would require leaning outside.
  • The window cannot be secured closed.
  • It is a designated escape window and the hinge or opening geometry may be safety-critical.
  • The handle or locking mechanism is being forced to make the window shut.
Still need help?

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Evidence

Sources used for this guide

We prefer primary UK guidance, regulators and manufacturers for technical and safety-sensitive claims.

  1. How to Fix Stiff/Loose Window Hinges (uPVC)Everest
  2. Window Care Guide: How to Care for Your WindowsEverest

Last reviewed: 31 August 2026. Home Manual updates review dates only when the substance of a guide is checked or changed.

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