Why choose Secondary Glazing?
Secondary glazing significantly reduces external noise, cutting sound levels by up to 54 dB. It is highly effective against low-frequency traffic noise, buses, and general urban disturbance—areas where standard double or triple glazing typically achieves only around 31 dB.
For best results, the secondary unit should be installed 150mm away from the primary window, creating an insulating air cavity. Acoustic glass from 6.4mm upward is selected based on the noise level and property requirements.
While complete soundproofing isn’t possible, secondary glazing provides a substantially quieter indoor environment and is often specified by acoustic engineers to meet demanding noise-reduction standards.
Secondary glazing improves thermal insulation, helping rooms stay warmer and reducing heating costs. By preventing warm indoor air from contacting the cold external window, it minimises heat loss and blocks draughts.
For optimal performance, the unit is fitted 80mm away from the primary window to create an insulating gap, often paired with Low-E thermal glass to reflect heat back into the room.
Independent tests show typical savings of £60–£150 per window per year, depending on the age and condition of the primary windows, making secondary glazing a cost-effective long-term investment.
Secondary glazing adds a discreet but powerful extra security barrier. Installed with toughened glass—five times stronger than standard glass—it is far more resistant to impact.
Laminated glass is also available, which cracks but stays intact for added protection.
Frames are fitted with internal locks, mechanically-joined aluminium profiles, and securely screwed fixings, making the units very difficult to force open or remove.
Overall, secondary glazing provides a strong deterrent and an additional layer of protection for your property.
Many units feature movable or removable panes for simple cleaning and maintenance. The latest Slide-Past vertical slider eliminates blind spots and improves access to the primary window.
Designed to complement existing windows, secondary glazing uses slim aluminium sightlines to remain discreet and suitable for both modern and traditional properties.
The result is a system that is practical, easy to maintain, and visually unobtrusive.
Secondary glazing helps prevent condensation by creating a tight internal seal while allowing controlled ventilation through unsealed primary windows or trickle vents.
This prevents the inner glass from becoming too cold, reducing condensation on both primary and secondary windows and protecting frames from moisture damage.
Our optional built-in trickle vents provide discreet, reliable background ventilation, helping maintain balanced humidity and preventing condensation throughout the room.
Secondary Glazing is adding an additional internal window to an existing external window.
This system provides greater thermal insulation, reduces noise intrusion and improves security to your home, business or listed property, without damaging the aesthetics of the original external window
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The following window glazing + installations are available:
Our premium products offer the following benefits:
A Vertical Slider is a type of window or glazing unit designed to slide open and closed along a vertical axis. It consists of two or more sashes (movable panels) that can slide up and down within the frame.
This design is often used in traditional or period-style properties but is also popular in modern buildings for its functionality and aesthetic appeal.
A Horizontal Slider is a type of window or glazing unit where one or more sashes slide horizontally along a track within the frame.
This design offers a sleek, modern look and is highly functional, providing ease of use and space-saving benefits.
A Hinged Unit refers to a type of window, door, or glazing system that operates on hinges, allowing it to open and close by swinging inward, outward, or in both directions, depending on its design.
Hinged units are one of the most traditional and versatile options for access and ventilation.
Lift-Out Units are a type of secondary glazing system designed to provide additional insulation, soundproofing, and energy efficiency for windows.
These units consist of a removable glazed panel that can be lifted in and out of the frame for ease of access, cleaning, or maintenance.
