uPVC and composite door locks in Stevenage, Hitchin and North Herts

How does the lock on a uPVC door work?

Most uPVC and composite front and back doors use a multipoint lock. A long metal strip runs down the edge of the door, with a gearbox in the middle where the handle and key go. Lifting the handle pushes hooks, bolts or rollers along the strip into keeps on the frame. Turning the key then holds them there.

The key turns a euro cylinder, a separate part that slots through the gearbox. That design means a worn or weak cylinder can be swapped without changing the rest, but it also means the cylinder is the part a burglar is most likely to target.

What goes wrong with them?

Common problems include:

• the handle has to be forced up, or will not lift at all
• the key turns stiffly, or only when you push or pull the door
• the handle drops loosely and nothing happens
• the door will not lock, or will not open once locked
• the door catches on the frame or lets in draughts

Stiffness is often a warning sign rather than the fault itself. When a door drops or the frame moves, the hooks and rollers stop meeting their keeps squarely, and the extra force wears out the gearbox. Hinges and keeps can usually be adjusted, which is far cheaper than a failed mechanism.

What should I avoid doing?

Do not keep forcing a stiff handle or key. That is how a gearbox or cylinder breaks, leaving the door stuck shut or unable to lock. Spraying oil into the mechanism without knowing the cause rarely fixes the alignment problem behind it.

Can a failed mechanism be replaced?

Usually, yes. Gearboxes and whole multipoint strips are replaceable, but there are many designs, and a replacement has to match the existing one in size, backset and the positions of the hooks or bolts. A locksmith will normally need to see the lock, or at least photos of the edge of the door, to find a match. Older or discontinued mechanisms can take longer to source. If the door is stuck shut, the locksmith may first have to open it, sometimes by removing the cylinder, before the mechanism can be taken out and matched.

Is my door vulnerable to lock snapping?

Older euro cylinders can be snapped: the cylinder is broken at its weakest point, which gives access to the lock. Police forces in England have repeatedly warned about this method.

If your door has its original cylinder, check its markings. A cylinder carrying the TS 007 Kitemark with three stars has been tested against snapping and other common attacks. So has the combination of a one-star cylinder with two-star security handles, which protect the cylinder face. A one-star cylinder on its own does not meet that level.

It also helps if the cylinder sits almost flush with the handle plate. One that sticks out a long way is easier to grip and break.

Does a new cylinder have to fit exactly?

Yes. Euro cylinders come in many lengths, measured from the central fixing screw to each face. Too long and it protrudes. Too short and it may not work the lock properly. A locksmith will measure before fitting.

Does changing the door itself need approval?

Fitting a new lock or cylinder in an existing door is not building work. Replacing a whole external door or window is controlled under the Building Regulations in England, and installers often certify that work through a Competent Person Scheme. If you live in a conservation area or a listed building, or in a part of Letchworth covered by the Heritage Foundation's Scheme of Management, check before changing the look of a door.

What should my enquiry say?

• your postcode
• whether the door is uPVC or composite, and front, back or patio
• what the handle and key do, and when the problem started
• whether the door is currently locked, unlocked or stuck
• any markings on the cylinder face or on the edge of the door
• a note if you can send photos, as these help with identifying the mechanism