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How to Open a Jammed, Stuck, or Seized uPVC Window

I couldn’t open the window, it was stuck, jammed and seized shut. The window handle moved, but the window just won’t open?


When you close the window, the handle gearbox pushes shootbolts (espag or espagnolette) and roller cams (mushrooms) out to lock the window in the outermost corners.

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uPVC Window Lock Faults:

The window handle gearbox can break (which is often the case), or the shoot bolt (espag or espagnolette) and roller cams (mushrooms) jam or seize. When the gearbox breaks, it doesn’t allow the shoot bolts and the roller cams to return to the open position and the window won’t open.

uPVC Window Lock – Parts Description:

Note: The parts below are for illustration only, as they come in different shapes and sizes from various manufacturers… uPVC and PVCu are the same material, just a different pronunciation.

How do I Open the Jammed or Seized Window?

It’s a fairly easy process to open the window. The difficulty is when there is:

  • Only a small gap to insert a simple tool,
  • Or, the roller cam is stiff to move.
The handle moved, but the window just won’t open? – Quick Overview

The text and images below, describe how we do it.


  • It may seem daft but, don’t fall out of an open window! Be safe! It’s easily done…
  • uPVC windows are made of soft plastic and can easily be damaged, scratched or gouged.
  • When working on a window, beware of dropping tools and other things out of the window. “Lucky” the cat might not be so lucky?


You will need something fairly thin bent at a right angle. You could use a:

  • Bent nail.
  • Allen key.
  • Or a pick.
  • And pliers to help pull the tools.
uPVC Window - Jammed, seized or Stuck Window - Tools
uPVC Window – Jammed, seized or Stuck Window – The Tools Required

Once you have your tools, it’s trial an error to see which one fits best? Each window may have a different size gap between the window and frame, (and the gap can be different from one end of the window to the other…).

Inserting the Opening Tool in the Window Gap:

Where do I Insert the Tool?

The shootbolts are towards the opening ends of the window, above and below the window handle (side-hinged window), or to the left or right of the handle (top-hinged window) – See the image below.

uPVC Window - Jammed or Stuck Window - Shootbolt Positions (Top and Side Hung)
Jammed or Stuck uPVC Window – Shootbolt Positions (Top and Side Hung) Windows

Opening the Jammed uPVC Window – Moving the Shoot bolt Roller Cam:

  • Put the window handle in the open position. This will move any working shootbolts to the open position.
  • Insert a right-angled tool just past where the shoot bolt roller cam is likely to be (so the roller can be pulled towards the window handle – See the images below).
  • Push the tool between the window and the window frame, past the rubber seal. Be careful not to damage the seal or the plastic window.
  • Turn the tool through 90 degrees. Gently pull the tool towards the shoot bolt roller (in the direction of the window handle). Position the tool so it runs along the edge of the window. This is to ensure you don’t miss hooking the roller cam.
  • You should then feel the tool stop as it hooks the shoot bolt roller.
  • Pull the shoot bolt roller cam towards the window handle.
  • The shootbolt roller should move and release this end of the window.
  • Repeat if the opposite end of the window is also jammed?
  • The window should now open.

It can be an easy job. It’s only difficult when you can’t get the tool in the small gap, or the shootbolt mechanism is stiff or seized.

Opening a Stuck PVC Window – Demonstration (with an open window)

The handle moves but the window just won’t open? – Easy to Open Example
The handle moves but the window just won’t open? – Difficult to Open Example

Repairing a Jammed or Stuck uPVC Window:

The repair will usually involve either:

  • The replacement of the locking mechanism gearbox, as lugs can break off within the gearbox.
  • Checking the connection between the locking mechanism gearbox and the shoot bolts.
  • Freeing up or replacing the shootbolts and rollers.

Replacing the Window Locking Mechanism Gearbox:

Lugs can break off within the gearbox, or it can just fracture. To replace, remove the window handle and loosen the shoot bolts. You can then slide the gearbox out of the window frame (see the images below).

When you replace the gearbox, you can insert the gearbox in the window frame the wrong way round. All this does is change the direction that the window handle operates. Try the handle in the gearbox before you fit it in the window, or just turn the gearbox through 180 degrees.


As a temporary solution, you can often refit the shoot bolt gearbox without the shoot bolts (espag or espagnolette), so your window will still close and lock (by the handle latch only) whilst you wait for parts.

Checking the Connection Between the Locking Mechanism Gearbox and the Shoot bolts:

In some instances, the shootbolt can become disconnected from the handle gearbox. Refit, checking that the connection lines up correctly and is secure.


When uPVC windows are manufactured, the shoot bolts are sometimes cut to length to fit the window. In some cases, they can be cut too short and can jump out of the housing. If this is the case, the shoot bolt (espag or espagnolette) may need replacing.

Freeing up or Replacing the Shootbolts and Roller Cams.

The shoot bolts and their rollers can become seized or corroded, as they are usually manufactured from mild steel with a thin electroplated finish.

Free up, clean and protect from further corrosion. Lubricate, or replace as necessary.

Opening a Jammed uPVC Window – Hints and Tips:

– Place thin cardboard against the window to help protect the plastic…
– Which way round do the window handles go?

For verticle window’s it’s easy, as the handle normally point downwards. For top hung windows (horizontal), imagine for a moment that you have turned the window sideways, and the window is now side hung (vertical). This gives you a good idea which way round the handle should go.

– My upvc window lock does not have the mushrooms but the locking mechanism is the same style. Any idea what I could do?

Have a look at another window (with the same mechanism) to work out if there is a method of opening – Choose a window on the ground floor, as you don’t want to fall out the window!

It could be that if you dismantle the lock you may be able to open the window? There may be some holes somewhere in the mechanism (shoot bolts) that you could grab with a pick. Practice, investigate with another open window (on the ground floor) to see if you can to work out a method of opening?