Why Window Security Matters
Windows are one of the most common entry points for burglars. According to figures from the Office for National Statistics, a significant proportion of break-ins involve entry through a window — making the type of window you choose an important security decision you can make for your home.
Beyond the obvious safety concern, window security has a direct impact on your home insurance. Many insurers require windows to meet minimum security standards as a condition of your policy. Failing to meet these standards could result in a rejected claim, even if the break-in wasn’t directly linked to a window. Make sure you check your home insurance policy before buying new windows with a different locking system.
Standard Windows vs Security-Rated Windows
Not all windows are built with security in mind. Standard windows are designed primarily for weatherproofing and thermal performance. Security-rated windows go further, incorporating reinforced frames, toughened or laminated glass, multipoint locking systems, and anti-tamper hardware that has been independently tested against forced entry.
The difference isn’t always visible to the naked eye, which is why understanding the ratings and certifications behind a window is so important before you buy.
Understanding Security Ratings
When shopping for secure windows, you’ll come across a number of ratings and accreditations. Understanding what these mean helps you cut through marketing language and make an informed decision.
PAS 24
PAS 24 is the primary UK benchmark for enhanced security in windows and doors. To achieve PAS 24 certification, a product must pass a series of rigorous tests simulating real-world attack methods, including manual forcing, cylinder attacks, and glass breaking. If you’re looking for a minimum standard to work from, PAS 24 is it.
Secured by Design
Secured by Design (SBD) is a police-backed accreditation scheme run by the UK Police Service. Products carrying the Secured by Design mark have met or exceeded PAS 24 and have been independently tested and approved. Choosing a Secured by Design window gives you the additional assurance that the product has been evaluated with crime prevention specifically in mind.
BS 7950
BS 7950 is an older British Standard for window security that predates PAS 24. You may still see it referenced by some manufacturers or in older documentation. While it represented a solid standard at the time, PAS 24 is now the more current and widely recognised benchmark, and most modern accreditations are based on it.
What These Ratings Mean in Practice
A rating or accreditation tells you that a window has been independently tested — not just that a manufacturer claims it is secure. When requesting quotes, ask installers to confirm which certification their products carry and request documentation if needed. A reputable installer will have no hesitation providing this.
Frame Materials & Security
The material your window frame is made from plays a significant role in its overall security. Each material has its own strengths and considerations, and the right choice will depend on your property, budget, and priorities.
uPVC
uPVC is the most common window frame material in the UK and, when manufactured to a high standard, can be extremely secure. Look for multi-chambered profiles, which add rigidity and make frames harder to force. Steel reinforcement within the frame is also a strong indicator of quality. Not all uPVC windows are equal, so always check whether the product carries PAS 24 certification rather than assuming security based on material alone.
Aluminium
Aluminium frames offer inherent structural strength, making them a strong choice from a security perspective. Their slim profiles allow for larger glass areas without sacrificing rigidity. Aluminium is also highly durable and resistant to warping, which helps maintain the integrity of locking mechanisms over time. It tends to sit at a higher price point than uPVC but is increasingly popular in both modern and period properties.
Timber
Timber windows are a traditional choice and remain popular in conservation areas and older properties where character is a priority. From a security standpoint, timber requires more consideration — the material can swell, warp, or deteriorate over time if not properly maintained, which can compromise the fit of locks and seals. That said, high-quality engineered timber windows with modern locking systems can perform well. Regular maintenance is essential to keep them secure.
Composite
Composite frames typically combine a timber core with an aluminium or uPVC outer layer, offering the aesthetic appeal of wood with improved durability and weather resistance. This combination also benefits security — the timber core adds rigidity while the outer casing reduces the risk of warping or deterioration. Composite windows tend to be among the more expensive options but offer a strong balance of performance, security, and appearance.
Glass & Glazing Options
The frame is only part of the security equation. The glass itself is equally important — a well-reinforced frame paired with inadequate glazing leaves a significant vulnerability. Understanding your glazing options helps you make a more complete security decision.
Toughened Glass
Toughened glass, also known as tempered glass, is processed using controlled thermal treatment to make it significantly stronger than standard glass. When it does break, it shatters into small, blunt fragments rather than sharp shards, reducing the risk of injury. From a security perspective, toughened glass is much harder to break through quickly, making opportunistic break-ins more difficult. It is commonly used in ground floor windows and doors where vulnerability to impact is higher.
Laminated Glass
Laminated glass consists of two or more panes bonded together with an interlayer, typically polyvinyl butyral (PVB). When broken, the interlayer holds the glass in place rather than allowing it to fall away — meaning even a compromised pane continues to act as a barrier. This makes laminated glass particularly effective against forced entry, as it is significantly harder to create a clearable opening. Many high-security window specifications require laminated glass as a minimum.
Double vs Triple Glazing
Both double and triple glazing offer security benefits over single glazing simply by adding more layers of glass. Double glazing is the standard across most modern UK homes and, when combined with toughened or laminated panes, provides a solid level of security. Triple glazing adds a further layer, increasing both thermal performance and the effort required to breach the window. While triple glazing is not always necessary from a security standpoint alone, it offers a meaningful upgrade in high-risk locations or where additional peace of mind is a priority.
Obscure Glass
Obscure glass is used primarily in privacy-sensitive areas such as bathrooms, ground floor side windows, or any glazing that faces directly onto a public space. While its main function is visual privacy rather than security, it plays an indirect role — preventing opportunists from surveying the interior of your home, identifying valuables, or assessing occupancy patterns. Obscure glass is available in a range of opacity levels and can be specified alongside toughened or laminated options for combined privacy and security benefits. See our decorative glass brochure for available options.
Locking Mechanisms
The locking system is one of the most critical components of a secure window. Even a well-made frame with quality glazing can be compromised by inadequate hardware. Understanding what to look for ensures you don’t overlook this important detail when comparing products.
Multipoint Locking Systems
A multipoint locking system secures the window at several points along the frame simultaneously, rather than at a single central point. This dramatically increases resistance to forced entry, as an intruder would need to overcome multiple locking points at once. Multipoint locking is a standard feature of PAS 24 certified windows and should be considered a minimum requirement for any ground floor or accessible window.
Shoot Bolt vs Hook Bolt Locks
Within multipoint systems, the individual locking points can take different forms. Shoot bolts extend straight into the frame, offering solid resistance against pushing or pulling. Hook bolts curve as they engage, making them particularly effective against the window being levered or pulled away from the frame. Many high-security systems combine both types to provide resistance against multiple attack methods.
Key-Operated Handles vs Thumb-Turn
Key-operated handles require a key to open the window from the inside as well as the outside, offering a higher level of security but reducing convenience in an emergency. Thumb-turn handles can be operated from the inside without a key, making them easier to use as an emergency exit but potentially less secure if the glass adjacent to the handle is broken. The right choice depends on the location of the window and your priorities — key-operated handles are generally recommended for ground floor and high-risk windows.
Anti-Snap, Anti-Drill & Anti-Pick Cylinders
The lock cylinder is a common target for experienced burglars. Cylinder snapping — where the lock barrel is snapped using brute force to expose the locking mechanism — is one of the most frequently used techniques. Anti-snap cylinders are designed to break at a sacrificial point that leaves the locking mechanism intact and inaccessible. Anti-drill cylinders contain hardened steel inserts that resist drilling, while anti-pick cylinders use security pins that defeat lock picking attempts. Look for cylinders that offer all three protections and carry a recognised rating such as TS007 3-star or Sold Secure Diamond.
Additional Security Features
Beyond the frame, glass, and locking mechanisms, there are a number of additional features worth considering when specifying secure windows. These elements are often overlooked but can make a meaningful difference to the overall security of an installation.
Hinge Protection & Restrictors
On casement windows, the hinges are a potential weak point. Security hinges are designed with additional features to prevent the window being lifted or forced from the hinge side, even when open. Hinge bolts can also be added to provide extra resistance against this type of attack. Hinge restrictors limit how far a window can be opened, which is particularly useful on ground floor windows where a fully open casement could otherwise allow access.
Beading — Internal vs External
Glazing beads are the strips that hold the glass pane within the frame. On externally beaded windows, these strips are accessible from outside — meaning the glass can potentially be removed without breaking it. Internally beaded windows keep this hardware on the inside, making it significantly harder to remove the glass from the exterior. When specifying secure windows, always opt for internal beading as a minimum.
Window Restrictors
Window restrictors limit the opening distance of a window, typically to around 100mm. They are particularly important on upper floor windows in homes with children, but also serve a security function on ground floor and accessible windows by preventing the window from being opened wide enough to allow entry. Restrictors are available with a key-release mechanism, allowing the window to be opened fully when needed while maintaining security at other times.
Smart & Connected Window Sensors
Smart window sensors can detect when a window is opened, broken, or tampered with, and send an alert to your phone or trigger a connected alarm system. While they don’t replace physical security measures, they add a valuable detection layer — particularly useful when you’re away from home. Many sensors integrate with popular smart home platforms and can be retrofitted to existing windows without modification to the frame or glass.
Cost Considerations
Security-rated windows represent an investment, but one that can pay for itself in reduced insurance premiums, increased property value, and long-term peace of mind. Understanding where the costs lie helps you budget effectively and avoid being swayed by price alone.
Price Ranges by Material & Rating
As a general guide, uPVC windows sit at the more affordable end of the market, with security-rated options typically carrying a modest premium over standard products. Aluminium and composite windows sit higher in price due to the materials involved and the manufacturing processes required to achieve security certification. Triple glazing and laminated glass specifications will also add to the overall cost. Always request itemised quotes so you can see exactly what you are paying for.
Impact on Home Insurance Premiums
Installing windows that meet recognised security standards — particularly PAS 24 or Secured by Design — can have a positive impact on your home insurance premium. Some insurers offer explicit discounts for security-rated installations, while others factor it into their overall risk assessment. It is worth contacting your insurer before purchasing to confirm what standards they recognise and whether certification documentation will be required.
Long-Term Value vs Upfront Cost
A cheaper window that lacks proper security certification may appear to save money upfront, but the long-term costs can outweigh the initial saving. Poor quality frames deteriorate faster, locking mechanisms can fail, and inadequate glazing may need replacing sooner than a well-specified alternative. When comparing quotes, consider the expected lifespan of the product, the warranty offered, and the reputation of both the manufacturer and the installer — not just the bottom line figure.
Checklist: What to Look for When Buying Secure Windows
Use this checklist when comparing products and requesting quotes. A reputable installer should be able to confirm each of these points without hesitation.
Security Ratings & Certification
- Does the window carry PAS 24 certification?
- Is it Secured by Design accredited?
- Can the installer provide documentation to confirm certification?
Frame & Glazing
- Is the frame multi-chambered and steel reinforced (uPVC)?
- Is the glass toughened, laminated, or both?
- Is the glazing internally beaded?
- Is double or triple glazing specified?
Locking & Hardware
- Does the window feature a multipoint locking system?
- Are the cylinder locks anti-snap, anti-drill, and anti-pick rated?
- Are security hinges fitted on casement windows?
- Are window restrictors included where required?
Installer & Warranty
- What warranty is provided on the product and the installation?
- Is the installer established and able to provide references or reviews?
- Is the quote itemised so you can see exactly what is included?
- Have you informed your insurer and confirmed their security requirements?
Frequently Asked Questions
Can I upgrade my existing windows rather than replacing them?
In some cases, yes. Locking mechanisms and cylinders can often be upgraded without replacing the full window unit, and window sensors or restrictors can be retrofitted relatively easily. However, if the frame itself is ageing, the glazing is single pane, or the window lacks internal beading, a full replacement is likely to be more cost-effective in the long run. An installer can assess your existing windows and advise on whether upgrading or replacing makes more sense for your situation.
Do secure windows affect ventilation?
Not significantly. Most modern security-rated windows are designed with ventilation in mind. Window restrictors allow windows to be opened partially for airflow while maintaining security, and many frames include trickle vents that provide background ventilation without the need to open the window at all.
What is the most secure window style?
Fixed windows — those that do not open — are inherently the most secure, as there is no locking mechanism to defeat and no gap to exploit. Where an opening window is required, casement windows with multipoint locking tend to offer better security than sash or tilt-and-turn styles, though all can be specified to a high security standard with the right hardware and glazing. The style matters less than the specification — a well-specified sash window will outperform a poorly specified casement.
