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UPVC Door Won't Lock: Causes and Fixes

12 April 2025·4 min read

A UPVC door that won't lock is a serious security issue. In many cases it's a straightforward repair — but you need to act quickly. Here's what might be causing the problem and how it can be fixed.

The Door Has Dropped

This is the most common reason a UPVC door won't lock properly. Over time, the weight of the door can cause it to drop slightly on its hinges. Even a few millimetres of drop can be enough to misalign the locking bolts and hooks with the keeps in the door frame, making it impossible to engage the lock fully. The fix is usually a hinge adjustment — a quick and inexpensive repair.

The Gearbox Has Failed

The gearbox is the internal mechanism that converts the handle movement into locking point engagement. If the gearbox fails, the handle may turn but the locking points won't move. You may hear a clicking or crunching sound, or the handle may just spin freely. Replacing a gearbox is a standard repair for any UPVC specialist.

The Euro Cylinder is Worn or Damaged

If the key turns but nothing happens, or the key is very stiff, the problem may be with the euro cylinder (the barrel into which the key is inserted). Euro cylinders can wear out after years of use, or may have been damaged in an attempted break-in. Replacing a euro cylinder is one of the quickest and cheapest UPVC repairs available.

The Keeps Are Out of Alignment

Keeps are the metal plates set into the door frame that the locking bolts and hooks engage with. If the keeps have shifted or if the frame itself has moved slightly, the locking points won't engage correctly. Re-aligning or replacing keeps is usually a minor repair.

Need a UPVC Repair in Birmingham or the Black Country?

The Glass Guardian provides fast, affordable UPVC window and door repairs across Birmingham, Dudley, Walsall, Wolverhampton, and the surrounding area. Call for a free quote.