A Guide to Laminated Glass and Glazing Interlayers

What is laminated glass?

Laminated glass refers to two or more pieces of glass which are bonded together using a material such as plastic or resin.

In the event of breakage, these interlayers hold the shattered glass in place which significantly reduces the risk of injury to anyone nearby.

The laminating process involves a combination of heat and pressure to bond the glass and ensure there are no air pockets within the pane.

One advantage of laminated glass is that it has a higher thermal performance and can help to improve the thermal efficiency of your property. It also reduces the amount of UV radiation entering the property which helps to prevent furniture and flooring from fading.

At Sieger, we often use a combination of toughened and laminated glass to achieve the highest levels of safety and security.


What is a glazing interlayer?

A glazing interlayer is a layer of material placed between pieces of glass to bond them together. 

This material is usually plastic however this is not always the case. With fire-resistant glass, we use an intumescent gel interlayer between the glass.

Interlayers can be used to turn glazing into decorative design features. They can be coloured, include prints, fabric and even unique elements like grass.

laminated glass eaves with a security glazing interlayers

How is glass laminated?

There are multiple ways to laminate glass and how it’s done depends on the material being used. The most popular lamination techniques are interlayer lamination and resin laminated.

Interlayer Lamination is when an interlayer is placed between two pieces of glass. They are sealed together by a series of pressure rollers and then heated.

This combination of pressure and heat chemically and mechanically bonds the interlayer to the glass.

Resin Lamination is when two pieces of glass are held together and liquid resin is then poured into the small gap in-between.

Once the small cavity between the glass has been filled with the liquid resin this resin is then cured. This can either be cured using UV or through a chemical process.

Laminated glazing, especially using toughened glass, not only increases the strength and security of the glass but also improves the acoustic insulation, provides UV protection and can be used as a decorative element.

rooflight with internal laminated glass pane
shattered glass held together by a security interlayer
pvb vs sgp security interlayer

Glass Security Interlayers

There are two types of strengthening security interlayers that we use at Sieger: Poly Vinyl Butyral (PVB) and SentryGlas Plus (SGP). We highly recommend using a security interlayer for rooflights and floorlights, as well as any structural glazing.


What is a PVB interlayer?

Poly Vinyl Butyral is a resin interlayer. When used within a glass pane this interlayer will block approximately 99% of UV radiation from passing through. This will help protect internal materials from UV fading, such as real wood floors or expensive artwork.

When a PVB interlayer is used for glass units with exposed edges, such as a frameless glass balustrade, there is a chance it may start to decay after a year or two due to weathering.

At Sieger we tend to use a PVB interlayer for internal glass balustrades and an SGP interlayer for external frameless glass balustrades.


What is an SGP Interlayer?

SentryGlas Plus is an ionoplast interlayer made from tough plastic and is used to create stronger glass panes.

Similarly to PVB, if the glass breaks this interlayer will hold the pane together and prevent it from shattering. This makes it ideal for structural glazing where the glass bares the weight of the structure.



Decorative interlayers

Laminated glazing allows for flexibility in design, nearly anything can be incorporated into the interlayer for truly bespoke glazing.


Coloured interlayers

Coloured interlayers are where the material used for the interlayer, PVB for example, is coloured. We also offer a colour matching service to that the desired colour can be achieved.

Fabric interlayers

Fabric can also be placed between the glass panes during the laminating process to achieve the desired aesthetic.

Printed interlayers

You can create bespoke prints of maps, logos and marketing materials onto an interlayer and laminate it into a glass pane for decoration.

Screen printing can be used to write door numbers, building names and company logos onto glass doors and entrance ways.

laminated glass with a coloured interlayer
glass floor with a fire rated interlayer

Fire rated glazing

Fire rated glazing uses a transparent intumescent gel interlayer between glass panes. When heated this gel interlayer swells and created a barrier that slows the spread of the fire.

For more information contact our technical team or book a showroom visit where you can discuss your project in person and see the Sieger window systems.


To talk to the team, call 01494 722 882 or email [email protected]

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