Windows are the second most common entry point for UK burglars — after front doors. Yet upgrading your window security rarely means replacing the entire frame. A well-chosen lock costing as little as £5 can turn a flimsy standard catch into a genuine deterrent. In this guide we cover the best window lock types available to UK homeowners in 2026, which British Standards apply, and exactly which upgrades your insurer will thank you for.
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According to the Office for National Statistics, around 30% of residential burglaries in England and Wales involve entry through a window. Ground-floor windows and those hidden from street view are the most targeted. The good news: research from the Home Office consistently shows that even basic secondary locking significantly increases the time and noise required to force entry — and most opportunist burglars move on within 60 seconds if they encounter resistance.
Most standard window hardware — the plastic cockspur handles on PVCu windows or the simple cam fasteners on older timber frames — offers very little resistance to a firm shove or a screwdriver. Adding a secondary lock changes that calculation entirely.
Two standards matter for window security in the UK. BS 7950 is the British Standard for enhanced security performance of casement and tilt/turn windows — it covers the hardware (handles, locks, hinges) as a complete assembly. EN 14351-1 is the European standard for windows and external pedestrian doorsets, which includes a security classification from Class 1 (lowest) to Class 6 (highest).
For most home insurance purposes, insurers look for windows that meet the Secured by Design initiative requirements, which generally means BS 7950 compliant hardware or EN 14351 Class 2 or above. If you’re adding aftermarket locks to existing windows, look for products tested to BS 8621 (key-operated locks) or that carry Sold Secure certification.
“Windows meeting BS 7950 are at least five times more resistant to forced entry than standard hardware — a difference measurable in the time a burglar needs to gain access.”
Different frame materials and window styles call for different lock types. Here’s an overview of the main options available in the UK:
Sash jammers are surface-mounted devices that physically block the window from opening more than a fraction of an inch. They’re extremely popular because they fit almost any window — PVCu or timber — without drilling into the frame hardware. Prices start at around £5–£10 per lock. Look for models from Era, Yale, or Sash-Stop. They’re particularly useful on sash windows (hence the name) and on casement windows where the existing handle catch is weak.
These replace or supplement the existing handle and require a key to open. Many PVCu windows already have multipoint locking systems activated by lifting the handle — a key-operated lock adds an additional layer. ERA and Yale both produce key-locking cockspur handles (around £12–£20) and surface-mount key locks (£8–£18) compatible with most standard frames.
Restrictors limit how far a window can open — typically to 100mm for child safety (required under building regulations in rooms at height). Security-grade restrictors are cable or bar designs that also resist forced entry. Jackloc is the UK market leader for cable-type restrictors; prices run £15–£25 per window. These are ideal for upper-floor windows where you want ventilation without leaving an opening large enough for a person to climb through.
Hinge bolts fit to the hinge side of a casement window, locking the hinge into a fixed receiver even if the main fastener is forced. They’re cheap (around £5–£8 for a pair), unobtrusive, and particularly recommended for outward-opening casement windows where the hinge pins are accessible from outside.
For older timber sliding sash windows, frame bolts (also called sash bolts) screw through the meeting rail and into the frame, preventing the sashes from being slid apart. They cost around £8–£15 per pair and are a simple, insurance-compliant upgrade.
| Product | Type | Frame Compatibility | Approx. Price | Standard/Cert |
|---|---|---|---|---|
| Era 827 Sash Jammer | Sash jammer | PVCu, timber, aluminium | £6–£8 | BS 8621 |
| Yale P107 Sash Lock | Sash jammer | PVCu, timber | £5–£7 | — |
| Sash-Stop Heavy Duty | Sash jammer | PVCu | £9–£12 | Sold Secure tested |
| Era Cockspur Handle Lock | Key-operated handle | PVCu (cockspur type) | £14–£18 | BS 7950 |
| Yale P118 Window Lock | Key-operated surface mount | Timber casement | £10–£14 | — |
| Jackloc Pro-10 Restrictor | Cable restrictor | PVCu, timber, aluminium | £20–£25 | Child safety tested |
| Timberline Hinge Bolt Pair | Hinge bolt | Timber casement | £6–£8 pair | — |
Ground-floor windows are the primary risk and should be fitted with both a primary lock (ideally key-operated) and a secondary sash jammer. Upper floors still need attention — particularly those accessible via a flat-roof extension, bay window roof, or drainpipe. For those, a cable restrictor or hinge bolt offers good protection without the complexity of a keyed lock.
Most UK home insurers follow the Association of British Insurers (ABI) guidance, which recommends key-operated locks on all accessible ground-floor windows. Some policies specify BS standards explicitly; others use vague language like “adequate security.” The safest approach is to ring your insurer, describe your window lock upgrade, and ask them to note it on the policy. If they raise objections, check whether your windows are covered by the Secured by Design scheme.
If you’re also upgrading your alarm system, pairing good window locks with a graded alarm can unlock worthwhile premium discounts — read more in our guide to home security insurance discounts. For a broader overview of all the entry points in your home, our how to secure your home guide covers doors, windows, and outbuildings together.
Most window locks require nothing more than a screwdriver and 10 minutes per window. A few tips to get the installation right:
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