How to Repair a Lock in a uPVC Door

Most uPVC doors have a multi-point locking mechanism, more commonly referred to as MPL. These locks can be costly to replace but it is possible to repair component parts, which can save money on labor, as well as parts.

Sometimes, the problem with a lock on a uPVC door is actually the alignment of the door. If the lock can be locked with a key in the open position, the uPVC door may simply need to be realigned. Check the hinges for loose screws repair or tighten any hinge problems. If the hinges seem to be tight, the door may need to be toe and heeled that entails packing the uPVC frame and panel with plastic frame packers.
If you determine it is not the uPVC door itself, the problem may be with one of the components of the multi-point lock mechanism. If you have lost a key or want a new lock, you will be able to replace the cylinder. In order to obtain the correct replacement cylinder, you need to measure the lock: measure from one end of the cylinder to the middle of the central screw hole and then measure from the other end to the same place. These two measurements give you the size, for example 40/60mm or 45/50mm. Once you have determined the cylinder size, unscrew the fixing screw located halfway up the main lock strip on the edge of the uPVC door. Put the key in one side and put pressure on the other key hole. Turn the key one way but if the lock cylinder does not release, turn the key the other way. Once the cylinder is out put new keys into the new cylinder and turn the key until the cam is facing down. Slide the cylinder into position and replace the fixing screws on the side of the uPVC door.

If the cylinder turns but the locking bolts do not engage, the repair may require changing the gearbox of the lock. First, remove the original gearbox by removing the two fixing screws on the metal strip on the side of the uPVC door. Remove the gearbox and install new gearbox making sure that the metal sliders locate into the gearbox. Refasten fixing screws after installing new gearbox into the lock.
Occasionally, the lock cannot be repaired so the whole lock needs to be replaced. Replacing the whole MPL is not a complicated procedure if you replace like for like. Remove the cylinder, then the handle and then the faceplate screws from the uPVC door. When you remove the lock, look for a manufacturers name and measure the backset of the lock. The backset is measured from the center of the spindle to the edge of the faceplate. Replace the lock by reversing the steps used in removing the old lock.