The most effective approach is to consider the frame, glass, locks, hinges, installation and location of each window together.

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How Secure Is Double Glazing?

 

Modern double glazing can provide a good level of protection when the windows are correctly specified and installed.

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A secure window should combine:

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• A strong and stable frame

• Multi-point locking

• Secure handles

• Protected hinges

• Suitable glazing

• Internal glazing beads

• Reliable weather seals

• Correct frame fixings

• Proper installation within the structural opening

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The term security double glazed windows can describe many different products. Two windows may look almost identical but contain very different locking systems, reinforcement and glass specifications.

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Homeowners should therefore ask for a detailed product specification rather than relying on general claims such as “high security” or “burglar resistant.”

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Identify Vulnerable Windows

 

Not every window faces the same level of risk.

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Greater attention should normally be given to:

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• Ground-floor windows

• Windows beside entrance doors

• Rear and side windows hidden from view

• Windows accessible from flat roofs

• Basement and lower-ground-floor windows

• Windows close to drainpipes, walls or outbuildings

• Garage and utility-room windows

• Windows left open for ventilation

• Older frames with damaged hardware

• Windows concealed by high fencing or planting

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An upstairs window may also be vulnerable if it can be reached from a porch, extension, conservatory roof or neighbouring structure.

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A room-by-room security assessment can help identify where upgraded locks, laminated glass or complete window replacement would provide the greatest benefit.

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Multi-Point Window Locks

 

Many modern casement windows use a multi-point locking system.

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When the handle is turned, several locking points engage around the opening section of the window. These may include rollers, hooks, bolts or mushroom-shaped locking points designed to secure the sash against the frame.

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The effectiveness of the system depends on:

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• The number and position of locking points

• The strength of the keeps

• Correct alignment

• Frame reinforcement

• Handle security

• The condition of the internal gearbox

• Professional installation

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A window may appear to lock even when some points are not engaging correctly. Misaligned hinges or a dropped sash can prevent the locking mechanism from pulling the window tightly into the frame.

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Locks should operate smoothly without requiring the handle to be forced.

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Secure Window Handles

 

Lockable handles can prevent the window mechanism from being operated easily from inside if the glass is broken.

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However, the handle is only one part of the complete security system. Replacing a basic handle with a locking model will not resolve a damaged gearbox, weak frame or poorly engaging locking strip.

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When choosing handles, consider:

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• Key locking

• Resistance to forced operation

• Secure fixing screws

• Compatibility with the locking mechanism

• Ease of operation

• Child safety where appropriate

• Availability of replacement keys

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Keep window keys accessible to occupants but out of sight and away from the window itself.

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Keys should not be left permanently in handles where they could be reached through broken glass.

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Laminated Security Glass

 

Standard toughened glass and laminated glass provide different forms of protection.

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Toughened glass is heat-treated so that it breaks into relatively small pieces rather than large, sharp shards. It is commonly used for safety in doors, low-level glazing and other vulnerable positions.

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Laminated glass contains an interlayer that helps hold the glass together when it is broken. This makes it more difficult to create an immediate opening through the pane.

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Laminated glass may be suitable for:

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• Ground-floor windows

• Glazed entrance doors

• Side panels beside doors

• Easily accessible rear windows

• Windows protecting valuable contents

• Properties in isolated locations

• Windows hidden from public view

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A specialist installer can advise on the appropriate thickness and specification for the location.

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Security glass should be considered alongside the frame and locks rather than as a substitute for them.

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Internal Glazing Beads

 

Glazing beads hold the sealed glass unit within the frame.

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Internally glazed windows have the beads positioned on the room side, meaning they cannot normally be removed from outside without first gaining access to the property.

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Older externally glazed windows may require additional security measures to prevent the glass unit from being removed. The level of risk will depend on the frame design and how the glazing is secured.

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When comparing replacement windows, ask whether the proposed system is internally glazed and how the sealed unit is retained within the frame.

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Strong Window Frames

 

Frame strength is an essential part of double glazing security.

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UPVC frames

UPVC windows may include internal reinforcement within the profiles. The frame design, corner joints, locking keeps and method of fixing all affect security.

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A low-cost frame with inadequate reinforcement may flex under force even when fitted with good locks.

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Aluminium frames

Aluminium provides a strong and rigid frame material. Slim profiles can still incorporate secure locking systems and reinforced glazing arrangements.

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The security performance will depend on the complete tested window rather than the material alone.

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Timber frames

Well-designed timber windows can provide excellent strength and security. The quality of the timber, joints, hardware, glazing and installation are particularly important.

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Older timber windows may also be improved through repair, stronger locks and suitable glazing.

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Composite frames

Composite windows combine different materials and may provide high levels of rigidity, insulation and resistance to weathering.

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Always compare the performance of the complete window system rather than assuming one material is automatically more secure than another.

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Hinges and Hinge Protection

 

Window hinges can become vulnerable when they are worn, exposed or inadequately secured.

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Modern window systems may include hinge-side protection intended to prevent the opening section from being forced away from the frame, even if pressure is applied to the hinge side.

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Possible improvements include:

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• New friction hinges

• Hinge guards

• Additional locking points

• Improved sash alignment

• Reinforced frames

• Secure restrictors

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Hinges should be suitable for the size and weight of the opening sash. A heavy glazing unit supported by inadequate hinges may drop over time and prevent the locks from engaging correctly.

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Window Restrictors

 

Restrictors limit how far a window can open.

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They can be useful for child safety, fall protection and controlled ventilation, although security depends on the type of restrictor and how it is fitted.

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Basic restrictors should not be assumed to prevent forced entry. Where security is a priority, ask for a robust product designed for that purpose.

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Restrictors must also be considered carefully on windows that form part of an emergency escape route. They should not prevent occupants from opening the window when escape is required.

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Ventilation Without Leaving Windows Vulnerable

 

Leaving a ground-floor window open for ventilation can create an obvious security risk.

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Alternatives may include:

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• Background or trickle ventilators

• Secure night-vent positions

• Lockable opening restrictors

• Mechanical ventilation

• Opening less accessible windows

• Ventilating rooms while occupied

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A night-vent setting should not automatically be treated as fully secure. Some windows remain partly open and may be more vulnerable than when completely closed and locked.

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The safest arrangement will depend on the window design and the property.

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Secure Glazed Doors

 

Windows and glazed doors should be considered together. A secure set of windows will provide limited benefit if the adjoining entrance or garden door remains weak.

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Potentially vulnerable glazed doors include:

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• Front doors with large glass panels

• French doors

• Sliding doors

• Bifold doors

• Back doors

• Side entrance doors

• Glazed utility-room doors

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Security features may include:

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• Multi-point door locks

• Strong cylinders and handles

• Laminated glazing

• Internal glazing beads

• Reinforced frames

• Hinge protection

• Secure thresholds

• Anti-lift devices for sliding doors

• Locking points across bifold panels

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The meeting point between a pair of French doors or the panels of a bifold system requires particular attention.

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Sliding Door Security

 

Older sliding doors can become vulnerable where the moving panel can be lifted, forced or operated through worn locking hardware.

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Security improvements may include:

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• Replacement locking mechanisms

• Anti-lift devices

• Additional locking points

• New rollers and guides

• Laminated glass

• Reinforced interlocks

• Correct frame alignment

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A door that does not slide smoothly should be inspected. Forcing the handle or lock can damage the mechanism and make the door less secure.

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Bifold Door Security

 

Bifold doors contain multiple panels, hinges and locking points. Their security depends on the quality of the complete system and the way every panel is connected.

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When choosing bifold doors, consider:

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• The main access-door lock

• Locking points at the head and threshold

• Panel-to-panel hinges

• Anti-lift protection

• Glazing retention

• Cylinder protection

• Frame strength

• Professional installation

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Large openings must also be properly supported. Structural movement or a poorly installed frame can affect door alignment and prevent locks from engaging correctly.

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Repairing Existing Windows

 

Complete replacement is not always required to improve home security.

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Existing windows may be strengthened by:

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• Replacing broken handles

• Repairing locking mechanisms

• Installing suitable lockable handles

• Renewing worn hinges

• Adjusting dropped sashes

• Replacing damaged keeps

• Upgrading vulnerable glass

• Adding restrictors

• Repairing decayed timber

• Improving frame fixings where accessible

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A repair specialist should identify why the window is insecure rather than replacing one visible component without checking the complete system.

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Where several parts are worn or the frame itself is weak, full replacement may provide better long-term value.

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Signs a Window Is No Longer Secure

 

A window should be inspected where:

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• The handle feels loose

• The handle turns without engaging the lock

• The sash moves when supposedly locked

• The window does not close squarely

• Hinges are distorted or corroded

• Locking keeps are loose

• The frame is cracked or warped

• Glass is loose within the frame

• Seals and beads are damaged

• The window can be opened without a key

• Locking points do not engage

• Timber around the hardware is decayed

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Security faults should be addressed promptly, particularly on accessible windows.

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Installation Quality and Security

 

A secure product can perform poorly if it is incorrectly fitted.

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The installer should:

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• Measure the structural opening accurately

• Use suitable frame fixings

• Position fixings correctly

• Provide adequate support beneath the frame

• Check structural support above the opening

• Prevent excessive gaps around the perimeter

• Seal and finish the frame properly

• Adjust locks and hinges

• Confirm that every opening section operates correctly

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Expanding foam and decorative trims should not be relied upon as the only means of securing a frame.

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The window must be mechanically fixed to the surrounding structure in accordance with the product and installation requirements.

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Security Standards and Product Testing

 

When security is a priority, ask whether the proposed window or door has been independently tested to an appropriate recognised standard.

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The supplier should be able to provide information covering the complete product specification, including:

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• Frame system

• Glazing

• Locks

• Handles

• Hinges

• Reinforcement

• Opening arrangement

• Tested dimensions

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Changing one of these elements may affect the tested performance.

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Avoid relying on a security logo or general reference in a brochure without checking that it applies to the exact windows and doors included in your quotation.

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Window Security and Home Insurance

 

Some home insurance policies contain minimum-security requirements for accessible windows and external doors.

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Check the policy wording, particularly where the property:

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• Is left unoccupied for extended periods

• Contains high-value items

• Has previously suffered a break-in

• Is being renovated

• Has windows with damaged locks

• Uses a door or window as the main access point

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An insurer may expect working locks to be used when the home is unattended.

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Keep invoices, product details, certificates and photographs of upgraded windows and doors with your property records.

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Lighting and Visibility

 

Window security is not limited to glass and locks.

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External lighting and the surrounding layout can help discourage someone from approaching vulnerable windows unnoticed.

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Consider:

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• Motion-activated lighting

• Clear visibility from neighbouring homes

• Trimming dense planting

• Avoiding hiding places beside windows

• Secure side gates

• Locking ladders and tools away

• Avoiding wheelie bins or furniture that provide access

• Maintaining fences and boundaries

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Planting should not completely conceal ground-floor windows or doors from view.

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Alarms and Window Sensors

 

Window sensors can form part of a wider alarm or smart-home security system.

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Options may include:

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• Contact sensors

• Vibration detectors

• Glass-break sensors

• Smart notifications

• Integration with lighting or cameras

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Technology should support good physical security rather than replace it. A sensor may alert you that a window has been attacked, but strong glazing, frames and locks are intended to make entry more difficult in the first place.

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Security for Period and Listed Properties

 

Traditional and listed properties may require a more sensitive approach.

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Original timber windows can often be strengthened through:

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• Joinery repairs

• Improved catches and locks

• Discreet security fittings

• Laminated replacement glass where approved

• Secondary glazing

• Draught-proofing

• Careful frame reinforcement

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Listed building consent may be required before altering historic windows, changing the glass or adding visible security features.

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Secondary glazing can improve security by introducing an additional internal barrier while retaining the external window. The design should avoid damaging historic shutters, panelling or decorative finishes.

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Planning Permission and Building Regulations

 

Like-for-like replacement windows in an ordinary house will not normally require planning permission. Additional restrictions may apply to flats, listed buildings, conservation areas and properties affected by an Article 4 Direction.

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Building Regulations may apply when complete windows are replaced or new openings are created. Requirements can include:

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• Safety glazing

• Ventilation

• Thermal performance

• Means of escape

• Structural support

• Protection from falling

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Security improvements must not prevent a required escape window from operating correctly.

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Establish the relevant requirements before ordering replacement windows or altering existing openings.

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Questions to Ask Your Window Installer

 

Before accepting a quotation, ask:

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• Has the complete window been security tested?

• What locking system is included?

• How many locking points are provided?

• Are the frames reinforced?

• Is the glazing retained internally?

• Where will laminated glass be used?

• Is hinge-side protection included?

• Which handles and cylinders are specified?

• How will the frames be fixed to the building?

• Are secure ventilation options available?

• Which guarantees apply to locks and hardware?

• What certification will be supplied?

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The answers should be included in the written specification rather than left as verbal assurances.

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Find Trusted Window and Door Installers

 

Strengthening home security requires a coordinated approach. The glass, frame, locks, hinges and installation must work together to protect vulnerable openings.

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APN Double Glazing can connect homeowners with experienced local installers for secure double glazing, replacement windows, entrance doors, French doors, sliding doors and bifold systems.

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Get in touch for expert advice and a free, no-obligation quotation for improving the security of your windows and doors.

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