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 a different way. Each has its own benefits and applications.
|Laminated Glass||Toughened Glass|
|European Standard Number: BS EN 14449||European Standard Number: BS EN 12150|
|Can be 'broken' and cracked||Is four times stronger than ordinary glass|
|Is held together by the PVB layer, which is difficult to pierce||Shatters into small granular pieces with dulled edges for safety|
|Required in car windscreens||Required in windows up to 800mm from ground level and 1,500mm for doors with glazing|
|Enhanced noise reduction||No noise reduction|
|Enhanced UV resistance||No UV resistance|
|Chosen for security or safety||Chosen for safety|
|Usually has a B/2 class rating||Usually has the highest safety rating A/1|
|More expensive but offers more protection||More economical and used more often as safety 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 that if it breaks, the glass is fused to the PVB layer and stays in place. For this reason, it’s used in skylights or glass ceilings to avoid glass shattering and falling from above.
Laminated glass is also used for car windshields and the cockpits of airplanes to avoid glass being sprayed into the face and eyes if the windscreen should shatter at speed.
The benefits of laminated glass
Laminated glass is useful for additional security on secluded doors and windows to the rear of a property. If the glass is broken by an intruder, it’s difficult to pierce and gain entry because of the PVB layer.
The PVB layer will reduce the transference of UV and solar gain which makes it a useful application for south-facing windows to protect furniture.
Laminated glass can help with noise reduction because the PVB layer disrupts sound waves as they pass through the glass. Sound can be reduced by up to 40dB which has the effect of seeming to move the sound further away.
In domestic properties, laminated glass will protect adults, children and pets from damage if a glazed door should break from impact.
How to tell if glass is laminated
As the laminate layer is so thin, unless you have a trained expert eye, it’s difficult to detect any perceptible difference in the glass. The only way to see the PVB layer is at the edge of the glass, but that would usually be hidden in a glazed unit.
Safety glass should be marked by a kitemark and the Standard for laminated glass is: BS EN 14449.