Door Locks

How a uPVC Door Lock Mechanism Works

Most uPVC and composite doors use a multipoint lock: the long metal strip fitted into the edge of the door. French doors use one on the main door, with shootbolts locking the second door at the top and bottom. In the middle is the gearbox (also called the centre case or lockcase), which holds the latch and deadbolt and is operated by the handle and the key cylinder. Above and below it are extra locking points, such as hooks, rollers, deadbolts or pins, which engage keeps on the door frame when the door is locked.

• Lift-lever locks: you lift the handle to throw the hooks or bolts, then turn the key to lock. This is the most common type on uPVC and double glazed doors.
• Key-wind locks: the key throws the locking points instead of the handle.
• Automatic locks: systems such as Yale AutoEngage throw the locking points as the door closes.

uPVC door lock replacement: gearbox or whole lock?

If the strip, hooks and rollers are in good condition and the fault is in the middle (the handle won't lift or drops, the latch sticks or the key won't turn fully), a replacement gearbox is often all you need and is the cheaper repair. If the strip is bent, the locking points are worn or broken, or no matching gearbox exists, replace the complete multipoint door lock.

Door Lock, Cylinder or Handle?

Not every door problem is the lock. If the key is stiff, snaps or won't go in, the problem is usually the door cylinder (the barrel the key goes into). If the handle droops or feels loose but the door still locks, the springs in the door handle may have failed. If the door only locks when you push or pull hard, the hooks may be catching the door keeps, which can often be adjusted or replaced. Looking for a patio door lock replacement? Sliding patio door locks and handles are in our patio door hardware range.

Sashlocks and Garage Door Locks

Timber front and back doors often use a mortice sashlock (a lock and latch in one case) instead of a multipoint lock. Measure the case depth, backset and the distance between the handle spindle and the keyhole. For garages and roller shutters, our garage door locks include security bolts and keyed-alike sets.

Frequently Asked Questions

Can I replace a uPVC door lock myself?

Usually, yes. With the door open, remove the handles and cylinder, take out the screws along the faceplate and slide the old lock out of the edge of the door. Fit the new lock the same way round. The new lock or gearbox must match the backset, centres, faceplate and locking-point positions of the old one.

Why won't my uPVC door lock?

The most common causes are a failed gearbox, a door that has dropped so the hooks no longer meet the keeps, or a worn cylinder. If the handle lifts freely without throwing the hooks, the gearbox has usually failed. If the hooks catch the keeps, the door or keeps need adjusting.

Will any multipoint lock fit my door?

No. Multipoint locks vary in backset, centres, faceplate width and length, and in the type and position of the locking points. Match all of these, or replace just the gearbox if your strip is in good condition.

Are composite door locks different from uPVC door locks?

Usually not. Most composite doors use the same kinds of multipoint lock and gearbox as uPVC doors, so you measure and match them in exactly the same way: backset, centres, faceplate and the position of the locking points.

Is it cheaper to replace the gearbox or the whole lock?

Replacing just the gearbox is usually the cheaper repair, because the strip and locking points stay in the door. It only works if the rest of the lock is in good condition and a matching gearbox is available for your lock.

Do I need new keeps with a new lock?

Not if you replace the lock like-for-like and the existing keeps are in good condition. If you change to a lock with different locking points, the keeps on the frame must match the new lock.

What if I can't identify my door lock?

Send us photos of the faceplate, the gearbox and any markings, with a tape measure in shot, through our part identification service and we will help you find a match.