Window Locks

Types of uPVC Window Locking Mechanism

Most opening uPVC windows use one of two locking systems. Look at the metal strip on the opening edge of the window (the sash) with the window open.

• Espag (espagnolette) lock: a single gearbox behind the handle drives a rod along the faceplate. Mushroom cams or rollers on the rod hook behind keeps on the frame when you turn the handle. The cams stay on the edge of the sash.
• Shootbolt lock: the gearbox drives bolts that shoot out of the top and bottom of the sash into keeps in the frame. Shootbolt systems often use separate extension rods connected to the gearbox, so the gearbox and rods may be sold separately.

Inline or offset?

On an inline espag, the square hole for the handle spindle sits in the centre of the faceplate. On an offset espag, the spindle hole is set back from the faceplate, so the handle sits further in from the edge of the window. Offset locks are made with either a flat faceplate or a U-rail (a U-shaped channel), so check which yours has.

How to Replace a uPVC Window Locking Mechanism

Open the window fully and remove the handle (two screws under the cover caps). Undo the screws along the faceplate on the edge of the sash, then ease the old mechanism out of its groove; it may need a gentle lever with a flat screwdriver. Fit the new espag lock or gearbox in the same position, refit the screws and handle, and check it locks smoothly with the window open before you close it.

Window Lock Replacement: Lock or Handle?

If the handle turns freely but the window will not lock or open, or the handle drops and feels loose, the gearbox inside the lock has usually failed and the lock needs replacing. If the handle itself is cracked, wobbly on its screws or the spindle has snapped, you may only need a new window handle. A stiff handle can also be caused by worn or misaligned window keeps on the frame.

Frequently Asked Questions

Can I replace a uPVC window lock myself?

Usually, yes. Most espag and shootbolt locks are held in by a handful of screws along the faceplate. The handle comes off first, then the old lock slides out of the groove in the sash. The new lock must match the type, backset and faceplate of the old one.

What does inline and offset mean on a window espag?

It describes where the handle spindle hole sits. Inline means it is in the centre of the faceplate; offset means it is set back from the faceplate by the backset measurement, usually 20mm or 22mm.

Do I need to replace the keeps as well?

Not always. If the keeps on the frame are worn, bent or the window feels draughty when locked, replacing them at the same time helps the new lock pull the window in tightly. Keeps need to match the cams on your lock.

Are shootbolt gearboxes and rods sold separately?

On many systems they are. Check whether your existing lock has separate extension rods clipped or screwed to the gearbox, and match the brand and series so the rods connect correctly.

Are window locks for double glazing different?

No. Double glazed uPVC windows use the same espag and shootbolt locking mechanisms described above. Match the type, backset, faceplate and locking points of your existing lock.

What if I can't find a name on my window lock?

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