A window that will not close is more than an inconvenience — a poorly compressed sash causes draughts, and forcing it damages the hardware. Here are the most common causes in order of likelihood.
1. The sash has sagged
The most common cause. Over the years the sash’s weight settles the hinges, and the bottom edge starts catching the frame or striker. The tell-tale sign — you have to lift the window by the handle to close it.
The fix: hinge adjustment vertically and horizontally. It takes a technician 10–20 minutes per window.
2. The handle won’t turn fully
If the handle stops halfway, one of the locking points is probably jamming, or the hardware needs lubrication. Do not force it — you can break the gearbox.
If the handle stopped suddenly with the sash open, the mis-operation lock has probably engaged. Press the lock lever against the seal and try turning the handle again.
3. Worn or broken hardware
If adjustment does not help, the locking mechanism has likely worn out — most often the corner drive or cams. These can be replaced individually (from €35) without changing all the hardware.
4. A deformed sash or frame
The rarest but most serious case — geometry changes due to building settlement or poor installation. On PVC windows sash geometry can often be corrected by re-packing the glass unit; wooden windows need frame work.
Conclusion: Do not force the window shut — that almost always makes the repair more expensive. Adjustment costs from €15 and in most cases fully solves the problem the same day.