Choosing secure replacement windows involves more than checking how many locks they have. The frame, glazing, hinges, installation and security testing all contribute to how well a window resists forced entry.
Understand PAS 24, multipoint locking, security glazing and what to ask before buying new windows for your home.
A secure replacement window relies on several components working together. Locks matter, but so do the frame, hinges, glazing, handles and the way the finished window is installed.
A window with six locking points is not automatically more secure than one with four. If the frame is poorly constructed, the hinges are vulnerable or the glazing can be removed easily, the number of locks tells you very little about its overall resistance to forced entry.
For homeowners comparing replacement windows, the most useful starting point is the security performance of the complete window system, rather than individual features described in a brochure.
None of these features should be considered in isolation. A good security specification is about how they work together.
PAS 24 is a recognised UK security standard used to assess the enhanced security performance of complete doorsets and windows.
The testing is intended to represent methods of attack associated with opportunistic burglary, including attempts to force entry through the window assembly.
Rather than simply checking whether a lock is fitted, PAS 24 assesses the performance of the window system under defined test conditions.
That distinction makes it particularly useful when comparing products.
No.
PAS 24 provides evidence that a particular window design has met defined security requirements. It does not guarantee that a window cannot be broken into, nor does it eliminate the importance of correct installation.
Security standards help establish a measurable level of resistance, not an absolute promise.
Not necessarily.
A modern window can have multipoint locking, key-locking handles and reinforced components without the exact configuration being covered by PAS 24 testing.
Window ranges may also be available with different hardware, glazing or opening arrangements.
When a supplier describes a window as PAS 24 compliant, ask whether that applies to the actual product and configuration being quoted.
Ask for the relevant test or certification details, including the standard and edition, the window system covered and any limitations affecting the available sizes or configurations.
You do not need to become an expert in security testing. You simply want confirmation that the claim applies to the window you are buying.
For current standards information, see Secured by Design's guidance on windows and glazing.
Secured by Design is a police security initiative that works to improve the security of buildings and products.
Its product accreditation scheme identifies products that meet relevant security requirements and have the appropriate independent certification.
For replacement windows, this provides another way to assess security claims beyond the number of locking points or the strength of the frame material.
PAS 24 is a security testing standard.
Secured by Design is a wider police initiative with product accreditation requirements that draw on recognised security standards.
They are related, but they are not interchangeable terms.
A supplier should not describe a product as Secured by Design accredited merely because it has some security features associated with PAS 24.
You can explore the scheme and its product requirements through the official Secured by Design website.
In England, Approved Document Q provides guidance on security requirements for new dwellings, including certain windows and doors.
It addresses the need for relevant openings to resist unauthorised access.
However, Approved Document Q does not generally impose the same requirement on an ordinary replacement window project in an existing house.
That is an important distinction.
For a new dwelling, security requirements may apply to accessible windows as part of the Building Regulations.
For a homeowner replacing windows in an existing property, the legal position is not automatically identical.
That does not make security testing irrelevant. Choosing an appropriately tested window can still be worthwhile, particularly for easily accessible openings.
The official reference is GOV.UK: Security in dwellings, Approved Document Q.
The applicable requirements depend on the nature of the building work.
A new dwelling created through conversion, for example, may have different obligations from a straightforward window replacement.
If the project involves more than replacing existing windows, establish which Building Regulations requirements apply before finalising the specification.
Multipoint locking systems secure an opening sash at more than one position.
Depending on the design, turning the handle operates locking components that engage with corresponding keeps around the frame.
This can help distribute resistance across the opening rather than relying on a single locking position.
Not automatically.
The position and construction of the locking points, the strength of the frame and the quality of the hardware all matter.
A well-designed system with fewer locking points may perform better than a poorly designed system with more.
This is why recognised testing of the complete assembly is more useful than comparing lock counts alone.
Espagnolette mechanisms use a locking strip operated by the window handle, allowing locking components to engage at different positions.
Shootbolts extend into receiving points to help secure the sash.
The exact arrangement varies by window system, and different mechanisms may be used together.
Ask which locking system is included in the quoted specification rather than assuming all casement windows use identical hardware.
Key-locking handles can provide an additional barrier to unauthorised operation.
However, they need to be considered alongside everyday practicality and emergency escape arrangements.
A window that forms part of a required escape route must remain suitable for that purpose.
Security features should never be specified without considering how the window will be used.
Locks attract most of the attention, but other components are just as relevant.
Hinges support the opening sash and form part of the connection between the sash and frame.
Depending on the window system, additional hinge protection or security features may be incorporated.
Their effectiveness depends on the complete design, including how the hardware is attached and how it performs under load.
It can, but material alone does not determine the result.
Modern uPVC systems may incorporate reinforcement and secure hardware, while aluminium systems use different frame construction methods.
A properly specified Casement Window should be assessed on its actual performance rather than assumptions about the material.
The same applies to Aluminium Windows and Timber Alternative Windows.
Our Window Materials guide explores the wider differences.
The way a sealed glass unit is held within the frame can affect security.
Internally glazed systems have retaining components accessed from inside the property, which can make external removal more difficult.
However, some externally glazed systems incorporate security measures of their own.
Neither construction method should be treated as proof of security without considering the tested window design.
Laminated glass is often worth considering where additional resistance to forced entry is a priority.
It consists of glass layers bonded with an interlayer that helps hold broken pieces together.
When the glass fractures, the interlayer can help maintain a barrier rather than allowing the pane to fall apart immediately.
The actual resistance depends on the glass specification, thickness, construction and how it is installed within the window.
These are different types of safety glazing with different characteristics.
Toughened glass is not automatically equivalent to laminated security glazing.
Likewise, not every laminated pane provides the same level of resistance. Security performance depends on the actual specification.
Not necessarily.
A ground-floor window accessible from a garden may present different security considerations from an upper-floor window with no convenient external access.
The appropriate glazing should be considered alongside the overall window system, the property's circumstances and any relevant requirements.
For more information, see our Glass & Glazing guide.
Window security should reflect how accessible each opening is.
Ground-floor windows are an obvious consideration, but they're not the only ones.
A first-floor window beside a flat garage roof may be more accessible than its height suggests. The same applies to windows near extensions, balconies or other structures.
For accessible ground-floor openings, ask about the security performance of the complete window system.
Check the locking specification, glazing, handle security and whether a tested security configuration is available.
Consider whether nearby structures provide access to otherwise elevated openings.
This can affect which windows deserve particular attention when choosing security specifications.
Privacy, ventilation and security often need to be balanced.
Obscure glazing may provide privacy, but it does not automatically provide additional security.
Bedroom windows can also have important emergency escape considerations.
Different window styles use different opening mechanisms and hardware arrangements.
That doesn't mean one style is automatically the most secure.
Casement windows commonly use hinged opening sashes with locking mechanisms engaging around the frame.
Their security depends on the particular hardware, frame and glazing specification.
Flush Windows have a different external appearance, with the opening sash sitting level with the surrounding frame.
The flush appearance itself does not establish better or worse security.
Sliding Sash Windows operate vertically and use different locking arrangements from conventional hinged casements.
Modern systems can incorporate security features while retaining traditional proportions.
Bay & Bow Windows consist of several window sections.
Each opening section needs to be considered as part of the complete specification.
Our Window Styles guide explains how these designs differ.
Some windows provide emergency escape openings.
When replacing those windows, the new opening configuration must be considered carefully.
A smaller sash, additional fixed glazing or different opening mechanism could affect the available escape opening.
If a window is intended to provide emergency escape, consider whether occupants can open it quickly and safely when necessary.
Key-locking arrangements, restricted openings and other security features must be assessed against the relevant escape requirements.
The right approach depends on the property and the applicable Building Regulations.
A secure window that cannot perform its required escape function is not a good specification.
For official guidance, see GOV.UK: Fire safety, Approved Document B.
A partially open window should not automatically be treated as secure.
Restrictors, night-vent positions and limited opening settings may be useful for controlling ventilation or movement, but they are not necessarily designed to resist forced entry.
That distinction matters particularly for accessible ground-floor windows.
Modern replacement windows can also be considerably more airtight than older frames, making appropriate background ventilation important.
Rather than relying on routinely leaving accessible windows open, discuss suitable ventilation arrangements as part of the window specification.
Our Window Energy Efficiency guide covers the relationship between airtightness and ventilation.
Even a window designed to meet a recognised security standard needs to be installed correctly.
The frame must be properly positioned, supported and secured within the building opening.
The manufacturer's installation requirements matter because the connection between the window and the surrounding structure forms part of the overall result.
A window should not be judged solely by the security features fitted in the factory.
Ask how the installation will be carried out and whether any unusual conditions around the opening need additional attention.
Consider a homeowner replacing eight windows in a two-storey house.
Five openings are on the ground floor, while three are upstairs. One upstairs bedroom window is accessible from a flat-roof extension.
The homeowner initially plans to order the same basic security specification for every window.
During the quotation process, they identify the accessible upstairs opening and ask whether a tested security configuration is available for the relevant windows.
They also check that the bedroom window retains suitable emergency escape provision.
The result is a more informed specification based on the actual property, rather than treating every opening as identical.
This is an illustrative scenario, not a completed Chatsworth installation or a claim of a measured reduction in burglary risk.
A useful security discussion should establish what is included in the quotation and which claims can be supported.
Ask the supplier:
You don't need the most expensive specification for every opening.
You do need to understand what you're buying.
For a wider quotation checklist, see our Questions to Ask Before Buying Windows.
When comparing replacement windows, it is worth asking about the actual components and configurations being supplied.
With windows manufactured in-house, discussions can go beyond the broad product name to cover the frame system, locking hardware, glazing and available specifications.
I'd rather explain exactly what security a window offers than describe it as burglar-proof. No responsible supplier should promise that.
The appropriate specification depends on the property, the opening and the available product configuration. PAS 24 certification or Secured by Design accreditation should only be claimed where it applies to the relevant product.
For further information, the following sources explain recognised standards and regulatory requirements:
These references primarily concern England and UK product standards. Building Regulations and their application can differ elsewhere in the UK.
Window security is one part of choosing a replacement window.
Once you've established the appropriate security specification, it's worth looking more closely at the glass itself.
Our Glass & Glazing guide explains double and triple glazing, safety glass, privacy and acoustic considerations.
You can also return to the Windows Buying Guide to compare window styles, materials, energy efficiency and replacement costs.
