Window Security Guide

Multi-point locking

Modern uPVC and aluminium windows should lock at multiple points around the frame rather than relying on a single catch. A multi-point locking mechanism engages hooks or shootbolts at several positions up and down the opening sash when the handle is turned, spreading the force needed to force the window open across the whole frame rather than one weak point.

Older windows, or budget replacements fitted some years ago, sometimes have only a single-point espagnolette lock, which is significantly easier to force. If your current windows only lock at one point, upgrading the locking gear, or the whole window, is worth prioritising.

Cylinder standards for doors and locking windows

Where windows or doors use euro-profile cylinders, the cylinder itself needs to resist snapping, a common method of forced entry where the exposed part of the cylinder is snapped off to access the locking mechanism directly. Cylinders meeting anti-snap standards, often marked with a British Standard kitemark or TS007 rating, are considerably harder to defeat this way.

It's worth checking existing cylinders on doors and any locking windows, since older stock fitted before anti-snap cylinders became common is a known weak point that's relatively inexpensive to upgrade.

Laminated glass

Laminated glass has an interlayer bonded between two panes of glass, so that even if the outer pane is broken, the interlayer holds together rather than creating a hole. This makes it much harder to reach through and operate a handle or lock from outside after an initial impact, unlike standard toughened or annealed glass which, once broken, leaves an open gap.

Laminated glass is particularly worth specifying for ground-floor windows and any window within easy reach of a door handle or lock, since reaching through broken glass to unlock a door from inside is a common and quick method of entry.

Hinges and restrictors

Hinge protection, sometimes called hinge side security or anti-tamper hinges, stops a window being levered off its hinges even if the locking side is somehow defeated. This is particularly relevant on outward-opening casement windows, where hinges are more exposed than on doors.

Restrictors limit how far a window can open, which is useful both for child safety on upper floors and, on ground-floor windows, as a way to allow ventilation without leaving a gap wide enough for entry. Restrictors that can be overridden by an authorised key give flexibility for cleaning or escape in an emergency while still restricting casual opening.

Handles and visible deterrents

Locking handles, which require a key to operate rather than a simple lever, add a visible and physical deterrent, since an opportunist can see at a glance that the window is secured rather than just closed. This is a small, low-cost upgrade that's worth considering on any ground-floor or easily accessible window.

• Key-locking handles on all ground-floor and accessible windows
• Anti-snap cylinders on any euro-profile locks
• Laminated glass near locks and on ground-floor panes
• Hinge-side security on outward-opening casements

PAS 24 and Secured by Design

PAS 24 is a British test standard that assesses a complete window or door, frame, glazing and hardware together, for resistance to physical attack methods commonly used by opportunist burglars. Products meeting PAS 24 have been through recognised testing rather than relying on individual component claims.

Secured by Design is a police-backed scheme that goes further, requiring products and installation practices to meet enhanced security criteria; it's often specified on new-build developments and can sometimes be a factor in home insurance discussions. Asking whether a window range has PAS 24 or Secured by Design certification is a reasonable question for any homeowner prioritising security.

Priorities for ground-floor and rear-of-property windows

Not every window needs the same level of specification. Ground-floor windows, windows accessible from a flat roof, garage roof or wall, and rear-of-property windows out of view from the street are the priority for enhanced security, since these are the locations opportunist offenders are most likely to target. Upper-floor windows facing a busy road can generally have a lower priority, though basic multi-point locking is still worth having throughout.

This is a sensible way to allocate a security-focused budget if you're not replacing every window on the property at once.

Insurance considerations

Home insurers increasingly ask about the type of locks fitted to windows and doors as part of a policy application, and some offer more favourable terms where PAS 24 or British Standard kitemarked hardware is confirmed. It's worth keeping any certificates or specification documents from a window installation, since these can support an insurance claim or a policy renewal query later on.

Common questions

Is laminated glass necessary on every window?

Not on every window, but it's a sensible priority for ground-floor windows and any pane within reach of a door lock or handle, since it prevents easy access after the glass is broken.

What does PAS 24 actually test?

It tests a complete window or door assembly, including frame, glazing and hardware, against recognised methods of forced entry, rather than assessing individual parts separately.

Can I upgrade the locks on existing windows without replacing them?

In many cases yes, particularly cylinders and handles, though the frame and hinge condition should be checked first, since upgrading hardware on a worn frame has limited benefit.

Do restrictors stop windows opening fully for cleaning?

Most restrictors have a key-release or override function, allowing full opening when needed while still limiting casual opening the rest of the time.