When a UPVC window lock jams you will have either one of two situations:

  • If you can’t open your UPVC window you will need to get it fixed as soon as possible to keep your home well-ventilated
  • If your UPVC window is open and you are unable to lock it, your home is not secure. A gap between the window and the frame could also lead to draughts and damp.

If your UPVC window lock is broken it is wise to ask a professional window fitter to take a look at it

Most UPVC windows are fitted with an espag lock which is operated using the handle. Before the lock breaks and jams the window lock is likely to have become more and more difficult to open.

If your window is open and the lock is broken, this is a much easier situation than if the window is jammed shut. When the window is open, you simply have to replace the window lock.

How to open a jammed UPVC window espag lock

Firstly, remove the window handle from the window. Sometimes the window handle is broken – not the actual lock.

If the handle is broken, it can be because the spindle bar from the window handle is broken. Alternatively, it could be that the small push button lock in the handle is broken.

How to check the UPVC window seals

The next thing you need to do is to check to see if the window seals are co-extruded seals or removeable seals. Co-extruded seals can’t be removed as they are part of the window frame itself.

What to do if your UPVC windows have a removable seal

If your UPVC windows have a removable seal, begin by removing the window handle. Using a flat screwdriver, grip the seal around the window frame and pull it out around the area of the window lock or push the seal down and out of its groove.

Now the seal has been removed, use a torch to see into the now empty groove and insert a small allen key into the gap between the frame and sash. Use vice grips to grip the end of the allen key and move the allen key until the head of the allen key is between the sash and the frame keep pin.

Once you have felt the locking point, pull in a quick motion against it. If the lock doesn’t release, reinsert the allen key on the opposite side and push against the lock instead of pulling. You are doing this because the locking points only move from left to right. If this still doesn’t work the lock may have seized, in which case give the vice grips a sharp tap with the hammer.

What to do if your UPVC windows have a co-extruded seal

If your UPVC windows have a co-extruded seal it will be a trickier job because you will not be able to remove the seal from around the frame to see the locking points.

Again, start by unscrewing the window handle to remove it completely. The using a thin, wide paint scraper gently pry between the sash and the frame until you see a small gap.

Insert an allen key into this gap and use vice grips to turn the allen key towards the sash until you hit the frame keep. When you feel the locking point pull against it. If this doesn’t work, insert the allen key on the other side and push against it.

If this doesn’t work either, give the vice grips a few taps with the hammer to add to the pressure to release the lock if the lock has seized.

Once you have opened your window, the lock is easy to replace – you can either do it yourself or consult an experienced window fitter.