Laminated Glass Explained
What Is Laminated Glass?
Laminated glass consists of two or more panes of glass bonded together using one or more interlayers.
The key difference from ordinary annealed or toughened glass is what happens when it breaks.
Rather than simply falling away from the opening, the fragments are normally retained by the interlayer.
This can provide useful performance for:
- Safety
- Security
- Acoustic insulation
- Residual containment
- Specialist glazing applications
The Quick Answer
Laminated glass is not simply:
“Stronger glass.”
Its main advantage is that the glass tends to remain bonded to the interlayer after breakage.
That can make it useful where the project needs:
- Safety glazing
- Increased resistance to intrusion
- Improved acoustic performance
- Glass retention after breakage
But the exact laminated glass specification matters.
Not every laminated pane provides the same level of performance.
How Laminated Glass Is Constructed
A typical laminated pane consists of:
Glass + interlayer + glass
The interlayer is commonly PVB-based, although specialist interlayers and constructions are also available.
Different combinations can be used to alter:
- Overall thickness
- Safety performance
- Security performance
- Acoustic performance
- Structural behaviour
Always use the actual manufacturer specification rather than selecting merely by nominal thickness.
What Does 6.4mm Laminated Mean?
A commonly encountered laminated safety glass is described as approximately 6.4mm laminated.
This usually consists of two nominal 3mm panes bonded around an interlayer.
Similarly, thicker laminated constructions may use thicker panes or additional interlayers.
However, avoid assuming that nominal thickness alone proves a required safety, security or acoustic classification.
The declared product performance is what matters.
6.4mm vs 6.8mm Laminated Glass
Builders often ask:
“What’s the difference between 6.4 and 6.8 laminated?”
The difference is not merely the extra 0.4mm.
The construction can incorporate different interlayer thicknesses and therefore potentially provide different performance.
This can affect:
- Security specification
- Safety classification
- Acoustic performance
- Overall sealed-unit thickness
Do not substitute one for another without checking the project and product requirements.
Laminated vs Toughened Glass
These two products behave very differently.
Toughened Glass
When broken, toughened glass is designed to fragment into many relatively small pieces.
Laminated Glass
When broken, the interlayer normally retains the fragments.
This means laminated glazing may maintain a residual barrier after breakage.
That can be useful for:
- Security
- Guarding applications
- Overhead glazing
- Specialist safety applications
depending on the design.
Is Laminated Glass Safety Glass?
Appropriately classified laminated glass can be used as safety glazing.
However, do not assume:
“Any laminated glass is automatically compliant safety glass.”
The product needs the correct performance classification for the intended use.
Part K identifies critical glazing locations where appropriate protection against impact is required.
Laminated Glass in Doors and Sidelights
Laminated safety glazing may be used in critical locations such as:
- Entrance doors
- French doors
- Bifolds
- Patio doors
- Door sidelights
- Low-level glazing
provided the particular product meets the applicable requirements.
The choice between toughened and laminated glass should be based on the complete specification.
Laminated Glass and PAS 24
This is one of the biggest areas of misunderstanding.
People often say:
“PAS 24 means you need laminated glass.”
That statement is too crude.
PAS 24 concerns the security performance of the complete window or doorset.
If laminated glazing forms part of the tested/certified configuration, then that specification matters.
Do not assume:
- All laminated glass automatically provides PAS 24 compliance.
- Every PAS 24 window requires identical laminated glass.
- Adding laminated glass turns an ordinary window into PAS 24.
Always follow the actual product evidence.
Laminated Glass and Part Q
Part Q deals with security in new dwellings.
Where a Part Q/PAS 24 configuration requires specific security glazing, that glass needs to be supplied as part of the compliant product arrangement.
Again:
Glass alone does not demonstrate Part Q compliance.
Acoustic Laminated Glass
Laminated glazing can be particularly useful for acoustic applications.
Special acoustic interlayers can help reduce sound transmission through the glass.
This is commonly considered for properties near:
- Main roads
- Railways
- Airports
- Pubs/nightclubs
- Industrial sites
- Mechanical plant
The important point is that ordinary laminated glass and acoustic laminated glass are not necessarily the same product.
If the specification includes an acoustic requirement such as Rw or Rw + Ctr, obtain the actual acoustic test/calculation data for the proposed build-up.
Asymmetric Acoustic Units
Good acoustic performance is often achieved using panes of different thicknesses.
For example, rather than using identical glass on both sides of a sealed unit, the specification may use:
- Thicker glass externally
- Laminated glass internally
- Different cavity width
- Acoustic interlayer
The purpose is to reduce coincident resonance and improve performance across a wider range of frequencies.
Is Triple Glazing Always Better for Sound?
No.
Triple glazing is not automatically acoustically superior to a well-designed asymmetric double-glazed unit.
Acoustic performance depends on the complete glass build-up and frame.
We’ll cover this in detail in the Acoustic Glass Guide.
Laminated Glass and Security
After breakage, laminated glass can remain held together by the interlayer.
This can make penetration more difficult than with glass that immediately falls away.
However, don’t describe every laminated pane as:
“Burglar-proof.”
Security performance depends on:
- Glass construction
- Interlayer
- Frame
- Beading
- Fixings
- Locks
- Complete tested product
Laminated Glass and Roof Glazing
Laminated glass is often used in overhead applications because retaining fragments after breakage can be particularly important.
Rooflight and overhead glazing requirements are application-specific.
Do not simply use a vertical-window glass specification in a roof without checking the rooflight manufacturer’s requirements and applicable safety design.
Laminated Glass and Guarding
Where glazing acts as a barrier or guarding element, residual performance after breakage can be critical.
This is not the same as ordinary safety glazing in a low-level window.
Structural glass and guarding require specialist assessment.
Do not assume 6.4mm laminated glass is automatically suitable as a balustrade merely because it is laminated.
Laminated Glass and Fire Resistance
Ordinary laminated glass is not automatically fire-resistant glass.
The presence of an interlayer does not make the pane EI30, EI60 or another fire classification.
Fire-resistant glazing is a specialist tested/classified product used as part of an appropriate fire-resistant system.
UV Reduction
Many laminated interlayers reduce a significant proportion of ultraviolet radiation.
This can help reduce fading of:
- Furniture
- Flooring
- Artwork
- Fabrics
However, do not market laminated glazing as providing absolute UV protection.
Use the manufacturer’s declared performance.
Weight
Laminated glass is heavier than thinner standard panes.
This matters with:
- Large doors
- Bifolds
- Sliding doors
- Opening windows
- Hinges
- Rollers
- Hardware capacity
A glass upgrade can push a sash or panel outside the system’s permissible weight.
Check before manufacture.
Common Laminated Glass Mistakes
Mistake 1 – Assuming laminated means PAS 24
It doesn’t.
Mistake 2 – Assuming every laminated glass is safety glass for every application
Check classification.
Mistake 3 – Treating 6.4 and 6.8 as interchangeable
Don’t substitute without evidence.
Mistake 4 – Assuming laminated means fire rated
It doesn’t.
Mistake 5 – Ignoring glass weight
Hardware limits matter.
Mistake 6 – Saying triple glazing is always acoustically superior
It isn’t necessarily.
Real-World Example
A contractor needs windows beside a busy road.
The specification asks for:
- Safety glazing
- Acoustic performance
- PAS 24
The cheapest response would be to add ordinary laminated glass.
That may not satisfy all three requirements.
The correct process is to establish:
- Required safety classification.
- Required acoustic performance.
- PAS 24 tested/certified glass configuration.
- Overall sealed-unit thickness.
- Frame and hardware compatibility.
One glass specification can then be selected to address the complete requirement.
Frequently Asked Questions
What is laminated glass?
Two or more pieces of glass bonded using an interlayer.
What happens when laminated glass breaks?
Fragments are normally retained by the interlayer rather than immediately falling away.
Is laminated glass safety glass?
Appropriately classified laminated products can provide safety glazing performance.
Is laminated glass stronger than toughened glass?
That’s the wrong comparison. They have different strength and breakage characteristics.
Does PAS 24 require laminated glass?
Follow the glazing specification covered by the applicable PAS 24 evidence.
Is 6.8mm laminated better than 6.4mm?
It may provide different performance, but thickness alone doesn’t determine whether it is appropriate.
Is laminated glass good for noise?
It can be, particularly where specialist acoustic interlayers are used.
Is laminated glass fire rated?
Not automatically.
Can laminated glass be used in bifolds?
Yes, subject to the system’s glass thickness, weight and security requirements.
Related Guides
- Toughened Glass Regulations
- PAS 24 Explained
- Part Q Explained
- Acoustic Glass Guide
- Fire-Rated Windows
- Part K Explained
Trade Tech Technical Support
If your project requires laminated glass, don’t simply write:
“laminated glass required.”
Tell us why it is required:
- Safety
- PAS 24/security
- Acoustic performance
- Overhead glazing
- Guarding
- Other specialist requirement
That makes it much easier to select the correct product.
Important: Safety, security, structural and acoustic requirements are performance-based. Nominal glass thickness alone does not prove suitability.