What architects need to know about specifying fire-rated glazing

Are you an architect preparing to specify fire-rated glazing? Learn the key facts about rating classifications, glass types and more.



When specifying fire-rated glazing for a project, there are several things to keep in mind. Some of them are highly technical.

If you take only one thing away from this article, however, it's this. Architects must specify complete, certified glazing systems. Glass, frames and hardware all need to be appropriately fire-rated – not just the glass.

One unsuitable component can invalidate the whole system, rendering the project non-compliant and causing delays. Working with a specialist supplier that can provide tested systems, appropriate certification and technical support can help ensure the specified configuration is suitable from the outset.

On top of this, you need to understand the fire-rating classification system and the various types of glass, frames and hardware. You'll also need to understand the trade-offs between performance and aesthetics that sometimes occur.

Architects make several common mistakes when specifying fire-rated glass. We've included them here so you can make the right decisions first time around.

But first, what does "fire-rated" mean in the context of architectural glazing?

Fire rating classifications

Under the European fire-resistance classification system in BS EN 13501-2, there are three main classifications for fire-resistant glazing. These are:

• Integrity only (E)
• Integrity and insulation (EI)
  
• Integrity and radiation control (EW)
  
  

Integrity-only (E) glass blocks flames and hot gases for a set time. E30, for instance, means the glazing maintains its integrity for 30 minutes. E-rated glass does not provide insulation, so radiant heat can pass through it.

Like integrity-only glass, integrity and insulation (EI) glass blocks flames and hot gases. It also limits heat transfer to the unexposed side, helping to protect people and materials from excessive temperatures.

Finally, integrity and radiation control (EW) glass prevents flames and hot gases from passing through while limiting radiant heat transmitted through the glazing.

If you're in England or Wales, the rating you need will depend upon Approved Document B (Fire Safety) of the UK Building Regulations.

System compatibility and assemblies

The whole assembly must be tested – not just the glass. This includes frame, seals, beads, fixings and hardware. The frame material must have the same fire rating as the glass, as must the surrounding wall or floor structure.

Glass types and performance

Different types of glass can be fire-rated. These include traditional wired glass, high-temperature ceramic glass and multi-layer laminated glass with an intumescent (swelling) plastic interlayer.

Each type of glass comes in different thicknesses and weights. Higher fire ratings and insulation properties require thicker, heavier glass.

When specifying your glass type, you need to consider secondary properties. Does your fire-rated glazing need to be impact-resistant, provide acoustic insulation or improve thermal efficiency? Find out before you specify.



Common mistakes

Here are five common mistakes that architects make when specifying fire-rated glazing.

1. Specifying fire-protective glass (integrity only) in locations that need fire-resistive glass (integrity and insulation).
   
   
2. Assuming that standard toughened or laminated glass meets fire-rating standards. In fact, these will crack and fail under thermal stress.
   
   
3. Mismatching glass and glazing systems. Remember that the whole assembly (glass, gaskets, framing, anchoring) must be tested and listed together as a complete system. An unrated or incorrect frame will invalidate the compliance of the fire-rated glass.
   
   
4. Exceeding maximum dimensions for vision panels. These limits are determined by the door leaf's fire-test evidence, certification and manufacturer guidelines.
   
   
5. In the USA, fire-rated glass must carry a W (hose stream test) designation. This doesn't apply in the UK or Europe.
   
   

Performance vs aesthetic trade-offs

Sometimes, architects face trade-offs between aesthetics and performance. This is less and less the case with glazing systems like ours, which have slim, attractive sightlines and high-quality finishes. Nevertheless, the following trade-offs can be an issue during the specification process.

Glass appearance

EI-rated glass can be thick, heavy and subtly tinted under some lighting. This can be a trade-off as EI-rated glass offers superior safety against the spread of fire, smoke and radiant heat.

Conversely, architects who specify clear ceramic or polished wired alternatives get glass that closely resembles standard annealed glass but lacks EI-rated glass's higher performance spec.

Glass size

UK Building Regulations limit the size of some applications of fire-protective glass. This can affect decisions at the design stage.

Profile appearance

Here at Wrightstyle, our sightlines are narrow, even in large-span, uninterrupted applications. Other providers, however, will give you fire-rated glazing systems that have unappealingly bulky profiles.

If you buy high-performance glazing systems and work with skilled, experienced installers, these trade-offs shouldn't be a problem. However, they're worth bearing in mind during the design and specification stages to avoid disappointment and delays.

How we can help

At Wrighstyle, we pride ourselves on assisting clients of all kinds with technical enquiries.

We regularly navigate our clients through the specification process. This includes a full estimating package for supply-only, fabricated goods and fabricated goods with glass.

We also provide project details and design assistance, including 3D images to help you visualise the fire-rated glazing in context.

Last but not least, we provide architectural specification management. This involves organising, updating and monitoring technical documents that dictate the materials and standards for your architectural project. 

All this adds up to compliance, stakeholder alignment and clear performance standards. So, if you have any doubts about the specification process, get in touch. We'd be delighted to help.

What's the difference between fire-rated glass and safety glass?

Safety glass is a family of glass products that resist impact and are designed to break safely. The two main kinds are laminated glass and toughened glass. These offer no inherent fire protection.

Fire-rated glass, by contrast, is specifically manufactured to withstand high thermal stress and to block the passage of fire, hot gases and – in the case of EI glass – radiant heat.

It often includes clear intumescent (swelling) interlayers that expand when they reach a certain temperature. This gives people more time to evacuate and emergency services longer to respond.

Are you looking for high-quality fire-rated glazing systems for doors, windows, screens or curtain walls? Get in touch with Wrightstyle today for comprehensive product advice.