A secure window depends on more than the number of locking points fitted to it. Frame construction, hardware, glazing, installation and the design of the complete window all play a part.
This guide explains the main security considerations when choosing replacement windows and the questions worth asking when comparing different systems.
Window security is sometimes reduced to the number of locking points fitted around the frame.
That matters, but it is only one part of the picture.
The strength of the frame, locking hardware, hinges, glazing, handles and quality of the installation all contribute to how resistant the finished window is to forced entry.
This is why it is better to compare complete window specifications than to choose a product because one security feature sounds impressive in isolation.
If you are still deciding between different window types, our Choosing the Right Windows guide is the best place to start.
A secure window is made up of several components working together.
The outer frame and opening sash provide the structure that the locks, hinges and glazing are fitted into.
Different window materials and systems have different construction methods, but the important question is how the complete product has been designed and tested rather than simply whether the frame is made from uPVC or aluminium.
If you are still comparing those options, see our Window Materials guide.
Modern windows can use multi-point locking mechanisms that engage at several positions around the sash.
The number of locking points can be useful information, but more is not automatically better if the rest of the system is poorly designed.
The quality and positioning of the locking components matter too.
Hinges are another part of the window that can be targeted during an attempted forced entry.
Their design and how they interact with the frame therefore contribute to the overall security of the window.
Glass forms a large proportion of most windows, so glazing security matters alongside the frame and locks.
The type of glass, how the sealed unit is retained within the frame and the overall window design all influence the finished system.
Our Glass & Glazing guide looks at glazing choices separately.
Even a strong window specification needs to be fitted correctly.
A security-focused window is only useful if the frame itself has been properly installed and secured within the opening.
Not necessarily.
It is easy to compare two windows by counting locking points because the number feels objective.
The difficulty is that it does not tell you about:
A window with a long list of security features is not automatically superior to another system with a shorter marketing specification.
The better question is whether the complete window has been designed to resist the types of attack it may realistically face.
The handle is the part of the locking system homeowners interact with every day.
Depending on the window specification, handles may incorporate key locking or other security features.
This can help prevent the window from simply being operated if access is gained to the handle from outside.
Practicality still matters, though.
If key-locking handles are used, consider where the keys will be kept and whether the opening forms part of an emergency escape route.
Security should not make the window awkward or unsafe to use.
Homeowners sometimes focus almost entirely on the glass when thinking about security.
Stronger glazing can certainly form part of a security specification, but windows are generally attacked as systems rather than as isolated panes of glass.
The security of the glazing also depends on how it is held within the frame.
Laminated glass uses layers bonded together so that the pane tends to remain held together when broken.
It may be specified in locations where increased security or safety performance is required.
Toughened glass is designed primarily around safety. When broken, it behaves differently from ordinary annealed glass and may be required in certain locations.
Toughened and laminated glass are therefore not simply interchangeable terms for "strong glass". They perform differently and may be specified for different reasons.
Our Glass & Glazing guide looks at these choices in greater detail.
Another consideration is how the glazing unit is retained within the frame.
Many modern residential windows are internally glazed, meaning the components retaining the sealed unit are accessed from inside the property rather than externally.
That can make removal of the glazing unit from outside more difficult.
However, this is again something to consider as part of the complete system rather than using one construction detail as proof that a window is secure.
Potentially, because different styles open and operate in different ways.
Casement Windows usually use hinged opening sections with locking mechanisms positioned around the sash.
The specification of the frame, locks and hinges all contributes to security.
Flush Windows use a different external sash arrangement but still rely on the complete combination of frame, locking hardware, glazing and installation.
The flush appearance itself should not be interpreted as either inherently more or less secure.
Sliding Sash Windows operate vertically, so their locking arrangements differ from hinged casement windows.
Modern sash systems can incorporate contemporary security features while retaining the traditional method of operation.
Bay & Bow Windows contain several individual window sections.
Each opening section should therefore be considered as part of the overall security specification rather than assuming the architectural form itself changes the basic requirements.
Our Window Styles guide explains how these different window types operate.
Material alone is not enough to answer that question.
Aluminium is inherently strong and is frequently used for comparatively slim frames, but a secure window depends on far more than the raw strength of the frame material.
Modern uPVC systems can also incorporate reinforcement, multi-point locking, secure glazing and other security features.
Rather than assuming Aluminium Windows are automatically more secure than uPVC, compare the tested specification of the actual products you are considering.
The same principle applies when comparing Timber Alternative Windows.
Material choice should also take appearance, maintenance, cost and suitability for the property into account.
Not every window around a property presents the same level of accessibility.
Ground-floor windows, windows beside flat roofs and openings accessible from extensions, garages or other structures may deserve more attention than windows that are difficult to reach.
That does not necessarily mean specifying a completely different window system.
It may influence:
Security is most useful when considered in the context of the individual property rather than assuming every opening presents exactly the same risk.
Homeowners naturally want windows that can provide ventilation without leaving the property unnecessarily vulnerable.
Different opening configurations can provide varying degrees of ventilation, but a partially open window should not automatically be treated as secure simply because it is held in a restricted position.
If you regularly leave windows open for ventilation, think about which openings are accessible from outside and how the room is used.
Ventilation is an important part of a comfortable home, but it should be planned rather than achieved by routinely leaving vulnerable windows wide open.
Our Window Energy Efficiency guide also explains why controlled ventilation remains important when upgrading older windows.
There is little value in specifying security features that make a window frustrating to use every day.
Consider:
A good specification should balance security with practical everyday use.
That balance may be different in a ground-floor living room compared with an upstairs bedroom.
Some windows may form part of the means of escape from particular rooms.
Where that applies, changing the size or configuration of the opening can have consequences beyond appearance and security.
This is another reason not to redesign window configurations purely on aesthetics without considering how each room functions.
The requirements depend on the property and circumstances, so this is an area where assumptions are best avoided.
If an existing window appears to provide an emergency escape opening, raise that during the survey rather than simply requesting a smaller opening section.
When comparing quotations, useful questions include:
You do not need to interrogate an installer with a technical checklist for every window.
The purpose of asking is simply to understand what you are being quoted for and whether two quotations are genuinely comparable.
Our Questions to Ask Before Buying Windows guide covers the wider quotation process.
This is particularly important when comparing products online.
A window range may be available with different:
The photograph and product name alone may therefore not tell you exactly what will be installed in your home.
When security matters to you, ask whether the specification being discussed is standard on the exact window you are buying or an optional upgrade shown in broader product literature.
Security understandably matters, but it should sit alongside the other requirements of the project.
A window still needs to:
The best window is not necessarily whichever option has the longest security specification.
It is the one that provides an appropriate level of security while also doing everything else the property needs.
If you are still comparing the wider options, return to the Choosing the Right Windows guide.
The next chapter is Glass & Glazing, where we look more closely at double and triple glazing, safety glass, privacy, noise and other glass specifications.
You can also explore the rest of the Windows Buying Guide:
