What is a secondary glazing unit, and how does it work?
It is an internal window installed on the room side of your existing window that improves thermal performance, reduces noise, and adds security without changing the exterior of the building.
What a secondary glazing unit is
A secondary glazing unit is an independent inner frame that sits behind the original window. The existing window remains in place, while the new unit adds performance from the inside, preserving the exterior character and avoiding disruptive facade work.
How it differs from double glazing
Double glazing replaces the whole window. Secondary glazing does not. It pairs with the original window to create a larger air gap, which is especially helpful for sound control and is often the only compliant option when you cannot alter the exterior appearance.
Key benefits you can expect
Secondary glazing improves thermal comfort, cuts draughts and reduces external noise. In busy areas near roads or rail, well-specified systems can reduce sound by about 50 to 65 per cent. A secure internal layer also makes forced entry harder, which is useful for homes and commercial sites.
Styles and configurations
Choose a format that suits the opening and your use of the room. Hinged units allow easy cleaning, sliding units support regular ventilation, lift-out panels suit occasional access, and fixed panes maximise performance when access is rare. Bespoke manufacture handles unusual sizes and shapes.
Ideal for heritage and commercial buildings
Listed properties and conservation areas often require the exterior to remain unchanged. Secondary glazing preserves original sightlines while upgrading performance from inside. For hotels, offices, and schools, installation is planned in stages to ensure day-to-day operations continue.
FAQs
- Is secondary glazing suitable for listed buildings?
Yes. It keeps the external appearance unchanged and is often preferred in conservation settings. - Does it really cut noise?
Yes. When designed well, it can reduce noise by roughly 50 to 65 per cent, which helps in areas near traffic, rail, or nightlife. - Will it help with heat loss?
Yes. The extra internal layer reduces heat loss and improves thermal comfort. - Can I still open and clean the window?
Yes. Hinged, sliding and lift-out options provide access for ventilation and cleaning. - Will it look obvious inside the room?
Quality systems are slim and discreet, so they blend with both period and modern interiors.
Call to action
Ready to improve comfort and noise control without altering your facade? Talk to HC Joinery via our contact page: https://www.hcjoinery.co.uk/contact-us/
