Composite Door Lock Replacement for a Door Not Locking

The cylinder is the part into which the key fits. A damaged cylinder can stop the key operating normally even when the mechanism behind it is sound. Replacing that cylinder is a different job from replacing the gearbox that moves the locking points. Our uPVC door lock replacement page explains those component choices for similar multipoint systems.

A handle that turns with very little resistance can point towards a failed connection or gearbox rather than a key problem. Tell us whether the handle still moves the bolts and whether the key feels different from before. We do not specify a particular make before checking what the door actually uses.

When locking works with the door open but fails against the frame, the locking points may not line up with their keeps. A dropped leaf or an incorrectly positioned keep can put pressure on a perfectly usable lock. Repeatedly lifting harder or forcing the key adds strain without correcting that alignment.

The hinge position, closing clearance and keeps are considered alongside the mechanism. Adjustment may be the repair needed, or it may be required together with a replacement part. For the difference between an alignment fault and a broken mechanism, read why a door will not lock. Stop testing if the handle or key is becoming difficult to move.

A replacement must suit the existing door thickness, handle arrangement and locking mechanism. Cylinder length matters because an unsuitable fit is not corrected simply by buying a more expensive part. We check the existing arrangement rather than assuming every composite door takes the same cylinder.

If improving cylinder security is the aim rather than repairing a fault, see anti-snap lock upgrades. That is a separate choice from fixing a door that has dropped. An upgraded cylinder will not straighten the leaf or restore a worn gearbox, so those faults still need their own assessment.

Explain whether the problem started suddenly, followed a lost key, or developed as the door became harder to close. A photograph of the handle and door edge, taken only if the door opens safely, helps identify the arrangement. Do not dismantle the mechanism to obtain a photograph or leave the entrance unsecured.

The quotation depends on which component has failed and whether alignment work is also necessary. We confirm the proposed work at a free in-person quotation, without treating every locking complaint as a whole-door replacement. If the entrance cannot be secured, call about emergency repairs rather than relying on repeated attempts to make the key turn.