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Why Has My uPVC Window Dropped and Become Hard to Close or Lock?

For a hinged uPVC window sash that now catches the frame, needs lifting by hand, or closes only if the handle is forced.

By Home ManualReviewed 4 September 2026Safety level S1UK guidance
Quick answer

What this usually means

A sash that has become hard to close should be treated as an alignment problem before the lock is blamed. The GGF advises checking hinges, catches and stays because damaged hardware can rack or distort a frame and make seals ineffective. Look for uneven gaps and the exact point where the sash rubs. If it needs lifting or force to latch, have the hinges, glazing support and locking keeps adjusted rather than grinding away the frame or forcing the handle.

Likely causes

What may be causing this

1

A hinge has worn or shifted

Clues: The hinge-side gap is uneven and the sash has visibly dropped.

What to do: Have the hinge position and condition checked.

2

The sash has racked out of square

Clues: Diagonal gaps differ and one corner hits the frame before the others.

What to do: A window technician may need to re-support or toe-and-heel the glazed sash.

3

Locking keeps are no longer aligned with the moving sash

Clues: The sash closes physically but the handle becomes very stiff at the last stage.

What to do: Have the alignment corrected before the gearbox is overloaded.

Diagnose the pattern

How to check what is happening

Inspect the gap around the closed sash
The gap narrows sharply at one corner

The sash is out of alignment.

Close the sash gently without turning the handle
It rubs or needs lifting

The physical alignment needs correcting before lock adjustment.

Operate the handle only when the sash is fully seated
It moves smoothly then

The locking mechanism may be sound and the problem is alignment.

DIY decision

Can you fix this yourself?

You can identify where the sash rubs and clean accessible hinges. Re-aligning a glazed sash or hinge system is better left to a window repair specialist.

You'll usually need:
  • Torch
  • Paper for marking the rubbing point
Step by step

What you can safely try

  1. 1

    Inspect the sash gaps

    Look for a dropped corner or uneven clearance around the frame.

  2. 2

    Test the physical close before locking

    A sash that rubs before the handle is moved has an alignment problem.

  3. 3

    Arrange adjustment

    Correcting the sash or hinges protects the locking gearbox from further strain.

Stop conditions

Call a glazier if…

  • The sash needs significant force to close.
  • A hinge is loose, cracked or pulling away.
  • The window cannot be secured after gentle closing.
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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. GGF Glazing ManualGlass and Glazing Federation
  2. When to repair or replace your windowsGlass and Glazing Federation

Last reviewed: 4 September 2026. Home Manual updates review dates only when the substance of a guide is checked or changed.

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