Can laminated glass be fire-rated?
Laminated glass is a versatile product, used in everything from windshields to aquariums. But can it also be fire-rated?
Laminated glass is versatile. It can be used for safety, security, style, thermal efficiency, UV resistance and
soundproofing. But can it offer fire protection where it's needed?
The short answer is yes. Fire-rated laminated glass – or laminated fire glass – consists of laminated glass with clear intumescent (swelling) interlayers.
In a fire, these interlayers expand into thick and typically opaque barriers against flames, smoke and radiant heat.
Laminated fire-rated glass is commonly used for fire doors, interior wall partitions, corridor screens, atriums, external windows and external facades. More generally, it's used where fire safety, impact resistance and post-breakage safety are required.
How does fire-rated laminated glass work?
When a fire breaks out, fire-rated laminated glass does four things:
- The outer layer (facing the fire) shatters.
- The hidden interlayer activates with heat and rapidly expands into a thick, solid, usually opaque barrier.
- The swollen layer holds the broken glass firmly in place. This prevents the fire and toxic smoke from passing through.
- The glass blocks infrared and radiant heat transmission.
How is laminated fire glass rated?
Laminated fire glass is rated by how long it stops flames, hot gases and heat when tested in a furnace. Ratings consist of letters and numbers signifying the glass's function and fire-protection duration, respectively.
Glass rated E (integrity) keeps out flames and hot gases. Glass rated EI (integrity and insulation) keeps out flames, hot gases and high heat.
To take two examples:
- An E30 sheet of laminated glass would block flames and hot gases for 30 minutes.
- An EI120 sheet would block flames, smoke and heat for 120 minutes.
The rating is established during testing, where assemblies are put in test furnaces that match real-life fire levels.
Laminated fire-rated glass also comes with a safety rating – for instance, EN 12600 or BS 6206. These demonstrate to specifiers that the glass prevents injuries on impact with humans.
What's the difference between monolithic and laminated fire glass?
Monolithic fire glass is a single pane of fire-rated ceramic glass or toughened glass. It blocks flames and smoke.
Laminated fire glass, by contrast, uses multiple layers of glass bonded with a clear plastic or intumescent interlayer. This blocks radiant heat and keeps the barrier intact if the unit cracks.
What are the different kinds of laminated fire glass?
There are three main kinds of laminated fire glass: gel laminated glass, laminated glass with intumescent interlayers and resin laminated glass.
Gel laminated glass
Gel laminated glass has clear, liquid or gel-based intumescent interlayers between the glass panes. When exposed to fire, the gel expands and turns opaque. It absorbs huge amounts of heat and carries a high EI rating.
Laminated glass with intumescent interlayers
Laminated glass with intumescent interlayers is similar to gel laminated glass. However, the interlayers are solid and made of sodium silicate or special resins. These swell into rigid, fire-blocking barriers when near fire.
Resin laminated glass
Resin laminated glass has a special clear resin between the panes. It's E-rated, meaning it provides basic protection against flames and hot gases. It also holds broken shards in place on impact. However, it offers only minimal resistance to heat transfer.
What are the benefits of laminated fire glass?
The core benefits of laminated fire glass all relate to the safety and fire protection it provides.
Laminated fire glass contains fires within specific building compartments, keeping escape routes safe for occupants.
It also reduces the transfer of dangerous radiant heat during a fire. And if it breaks under impact, the broken pieces stay stuck to the inner plastic interlayer. This prevents broken glass from falling, protecting building users and simplifying clean-up.
On top of this, laminated fire glass has all the benefits of standard, non-fire-rated laminated glass. These include enhanced security, soundproofing and UV blocking.
Security-wise, laminated glass provides a robust physical barrier, protecting buildings from forced entry, break-ins or physical impact.
In terms of sound, laminated glass dampens outside noise, making buildings more pleasant environments to be in.
Whereas standard annealed glass lets some harmful UV rays through, laminated glass filters out 99% of them. This protects furniture and carpets from fading under UV exposure.
What are the limitations of laminated fire glass?
One limitation of laminated fire glass is the temperature sensitivity of the intumescent interlayer.
While invaluable during a fire emergency, this can cause problems if the glass is exposed to prolonged high temperatures. If the sunlight is strong enough and lasts for long enough, the interlayer can degrade, bubble or even activate.
Laminated glass carries a risk of delamination when exposed to high heat or moisture. This can weaken the edge seals and cause the unit to turn cloudy or begin to peel.
It's heavier and thicker than standard glass. That means it requires heavy-duty – and fire-rated – framing and glazing systems. Similarly, maximum panel dimensions are capped according to fire tests.
For many, however, laminated fire glass remains an investment worth making – primarily because of the high levels of security and fire protection it provides.
How we can help
At ToughGlaze, we supply fire-rated laminated glass. It's cut to size, certified to BS EN 1364-1 and can be rated from E30 to EI120. Maximum panel sizes are 1,388 by 2,389 millimetres.
Like all our products, our fire-rated glass is accredited and manufactured in line with all relevant industry standards.
Do you need laminated fire glass for your project? Don't hesitate to get in touch with our experts to discuss your needs or request a quote.
