Safety Glass: Is Laminated Glass or Toughened Glass the Best Option?

Glass is a superior material, but windows, doors and large expanses of glazing can be lethal to a person if they break upon impact from accidental collision. For this reason, to protect people there are strict regulations for the use of safety glass.

What Is Safety Glass?

Safety glass is different from standard annealed float glass by the way it has been treated and how it breaks on impact. Annealed glass will break into large jagged shards that can pierce or cause deep life-threatening cuts to a person or animal.

To be called safety glass, the glass must pass testing to measure the impact it can withstand before it breaks and how it breaks.

There are two types of safety glass:

• Laminated glass
• Toughened (or tempered) glass

Find out the differences between laminated glass and toughened glass and when each is appropriate to use as safety glass. We also highlight the security standards to look out for.

What Is Safety Glass Used For?

Safety glass is used in any area deemed a 'critical location' where there is a risk that if the glass could break it would cause serious harm and injury.

The main applications of safety glass are:

• Low-level windows
• Glazing in doors
• Balustrades
• Glass stairs
• Glass floors
• Furniture such as shower screens, tables and worktops

What Is the Difference Between Toughened and Laminated Glass?

Toughened glass and laminated glass are often confused with each other, although they are different products manufactured in different ways. Each has its own benefits and applications.

Laminated Glass

Laminated glass is made by sandwiching a polyvinyl butyral (PVB) layer of thin plastic between two panes of annealed glass and fusing them together. The PVB thin layer is a minimum of 0.38 mm thick and can be used in multiples to create more resistance (for example, bulletproof glass) – 0.76mm is usually the maximum thickness for domestic glass.

The unique quality of laminated glass is how the glass is fused to the PVB layer and stays in place if it's broken. For this reason, it's used in skylights or glass ceilings to avoid glass shattering and falling from above.

As the laminate layer is so thin, it's difficult to detect any perceptible difference in the glass.

Safety glass should be marked by a kitemark and the Standard for laminated glass is BS EN 14449.

Read more: Laminated glass...

Toughened Glass

Toughened glass is sometimes known as tempered glass or safety glass. The glass is up to five times as strong as standard annealed glass and if broken, shatters into small granular pieces that don’t have sharp or jagged edges.

Toughened glass is made when annealed float glass is heated and then rapidly cooled with cold-blown air.

This process causes the outer surfaces of the glass to harden before the centre of the glass and this creates compressive stress making it harder to break.

Read more: Toughened glass...

Note that glazed areas in critical locations can be shielded by permanent screen protection to avoid the installation of safety glass. The permanent screen should comply with the following:

• Prevent a sphere of 75mm from coming into contact with the glazing (have gaps no more than 75mm)
• Be robust
• If it protects glazing installed to help prevent people from falling, it must be difficult to climb and not have horizontal railings

Safety Glass Classification and Marking

For Building Regulations, safety glass should be visibly marked with the grade of classification. The mark must contain the following:

• The manufacturer's name or trademark of manufacturer
• European Standard number e.g EN 14449
• Classification from the EN 12600 (or 6206) impact test e.g. 2B2

European Standard Number

• Laminated glass BS EN 14449: Glass in Building – Laminated and laminated safety glass – product standard
• Toughened glass BS EN 12150: Glass in Building – Thermally toughened soda lime silicate safety glass

Testing Classification

For glass to be deemed safety glass it must undergo testing via an impact test. Security glass is rated with a test to simulate a manual attack. 

Previous rating: BS 6206:1981 Specification for Impact Performance Requirements for Flat Safety Glass and Safety Plastics for use in Buildings (Partially superseded but remains current and is cited in Building Regulations)

BS EN 12600:2002 Glass in building – Pendulum test – Impact test method and classification for flat glass

The test uses a large pendulum with different levels of impact to measure the level of robustness of the glass as if a person ran into a large window at speed. The test demonstrates how the glass holds together to avoid piercing or cutting a person. You can see the Everest impact test below.

• BS 6206 grades are ‘A, B or C’ with ‘A’ being the highest performance grade
• BS EN 12600 grades are ‘1, 2 or 3’ with ‘1’ being the highest performance grade
• For comparison purposes between the two Standards grade ‘A’ = ‘1’, ‘B’ = ‘2’ and ‘C’ = ‘3’

References from:

• Guide to safety and security - Pilkington
• Protection from falling, collision and impact: Approved Document K
• Technical information about glass safety and protection - Saint Gobain
• Laminated Glass and Toughened Glass Leaflets - Glass and Glazing Federation