Summary
What is fire rated glass? Fire rated glass (sometimes called fire safety glass)is a type of glass that has undergone rigorous testing to ensure it can resist fire for a specific period of time, for example 30, 60, 90 or 120 minutes. The glass is just one part of a complete system including the frame, seals and hardware. Fire rated glass uses a classified system that defines its performance which are E (Integrity), EW (Integrity and Radiation Control) and EI (Integrity and Insulation) followed by a number showing the time it is effective for. E.g. EI 30.
Table of Contents
Glass often seems like the vulnerable point in a building’s defence, but fire rated glass is engineered to change that. As a key part of passive fire protection, it outperforms standard glazing by acting as a genuine barrier against extreme heat. In this article we are going to cover ‘what is fire rated glass?’ along with all of the key information that you need to know. So let’s begin.
While regular windows tend to shatter at around 120°C, fire rated glass maintains its integrity to stop flames and smoke spreading. This buys occupants vital time to evacuate and helps emergency services manage the situation. It is worth noting this isn’t just one product but a range of solutions, each adapted for specific building locations and performance requirements.
Understanding the Basics of Fire Rated Glass
Fire rated glass is a building material that has had rigorous testing to prove it can resist a fire for a specific duration. This performance is described by its fire rating, for example, 30, 60, 90 or 120 minutes. It is important to remember that the glass is actually part of a wider system. It relies heavily on the frame, seals and hardware to do its job. If every component does not meet the same fire rating, the protection is likely to be compromised.
Quick Comparison Guide
| Classification | Protection Level | Stops Flames/Smoke? | Blocks Radiant Heat? | Best Application |
|---|---|---|---|---|
| E (Integrity) | Basic | Yes | No | Windows/doors where people do not need to walk directly past the glass to escape. |
| EW (Radiation) | Intermediate | Yes | Partial | Areas requiring some heat control to prevent igniting nearby materials. |
| EI (Insulation) | High Performance | Yes | Yes | Critical evacuation routes (corridors/stairwells) where occupants must be protected from intense heat. |
Understanding Fire Rated Glass Classifications
Fire rated glass, also known as fire safety glass, is classified using a rating system that clearly defines its performance capabilities during a fire. In the UK and Europe, these classifications are crucial for meeting building regulations (like Approved Document B) and ensuring the right level of safety.
The classifications are typically represented by the letters E, EW and EI, followed by a number indicating the minutes it remains effective (e.g., 30, 60, 90, or 120).
E - Integrity Only
The ‘E’ classification represents the foundational level of fire protection.
- What it does: Stops the passage of flames and hot gases. It remains in the frame without collapsing.
- What it doesn’t do: It provides no protection against radiant heat.
Best for: Locations where the main goal is to prevent fire moving from one area to another, but where people are not expected to be evacuating directly past the glass. The heat radiating through this glass can still ignite nearby materials.
EW - Integrity and Radiation Control
The ‘EW’ classification provides a middle ground.
- What it does: It retains the integrity (E) of the first class but adds a level of heat resistance (W).
- How it works: This glass is designed to restrict the amount of radiant heat passing through to a specific safe level.
Best for: Specific internal or external applications where some heat control is needed, but full insulation is not required.
EI - Integrity and Insulation (High Performance)
The ‘EI’ classification represents the highest performance level.
- What it does: It stops the spread of flames and smoke AND creates a barrier against heat transfer.
- How it works: We achieve this by placing a clear intumescent interlayer between multiple sheets of glass. When exposed to heat, this layer expands and turns opaque to form a robust, insulating shield.
- Best for: Protecting evacuation routes (like corridors and stairwells). It ensures the non-fire side remains cool enough for people to walk past safely and prevents furnishings on the other side from spontaneously igniting.
Aluminium Fire Systems specialises in these high-performance solutions, supplying EI 30, EI 60, EI 90 and EI 120 products for critical areas.
For more information read our article on ‘Types of Fire Safety Glass: E vs EI’
What is fire rated glass used for?
Fire-rated glass is a key component in building safety strategies. It allows architects to create light, open spaces without ignoring compliance. You will commonly find these systems in commercial office atriums, hospital corridors and school stairwells where maintaining visibility is just as critical as the fire barrier itself
Fire Doors and Screens
Glass is a standard feature in modern fire doors and surrounding screens. These installations allow occupants to see escape routes clearly during an emergency while holding the fire in a specific compartment. EI rated glass is critical in these scenarios to ensure escape corridors do not become dangerously hot.
Partitions
Fire rated glass partitions divide spaces in open-plan offices, schools and hospitals without blocking natural light. They create specific zones like meeting rooms while ensuring that if a fire starts, it stays contained within the area of origin. This capability extends to the building envelope, allowing large glass facades and curtain walls to meet safety regulations without compromising the architectural design.
Educational Case Study
Educational facilities often struggle to balance strict fire safety regulations with the need for bright, conducive learning environments. The project required substantial glazing for a high-traffic area, but the safety codes demanded a rigorous 60-minute fire rating to protect the escape routes.
The Solution: We delivered eight large-format EI60 windows (approx. 1200mm x 1800mm). This allowed the architects to flood the space with natural light, avoiding a claustrophobic atmosphere, while fully adhering to the strict one-hour fire compartmentation required to keep students safe.
Choosing the Right Specification
Why wouldn’t you always choose glass with the highest fire rating?
Choosing your fire rated glass comes with the following considerations that you have to balance: safety, design and budget.
- Weight & Thickness: EI 120 glass is significantly heavier and thicker (up to 70mm) than E 30 glass. This requires more robust framing and heavy-duty hinges.
- Cost: High-performance insulation glass is more expensive to manufacture.
- Application: If a window is 10 metres up on an external wall, you likely only need Integrity (E) protection. If it is in a crowded lobby, you need Insulation (EI).
We hope that this article has answered your question of ‘what is fire rated glass?’ but if you do have any further questions that we can help with, then please contact us today.
Why Choose Aluminium Fire Systems?
The choice of supplier for fire rated systems affects safety, timelines and budget. Aluminium Fire Systems specialises in manufacturing:
We know that project schedules are tight so we focus on fast lead times and reliable nationwide delivery. We supply fire rated products to Coventry, Birmingham and locations across the UK. Buying directly from us means you get competitive pricing without sacrificing quality.
Every system is made in the UK and you get a full compliance pack.
The compliance pack includes:
Technical & Testing Documentation: Full technical specifications and valid test certificates.
Traceability Evidence: Production photographs and material receipts to demonstrate the golden thread of compliant materials.
Usage Guidelines: A comprehensive installation guide.
Formal Agreements: The signed order confirmation and the signed compliance agreement proving product classification.
What is Fire Rated Glass? Frequently Asked Questions
How do I know if my glass is fire-rated?
You can confirm the fire rating of your glass by checking the documentation provided when you purchased it. Here at Aluminium Fire Systems we issue a full “Compliance Pack” on completion which includes your fire windows/doors/partitions technical specifications, test certificates and a signed agreement to prove that your fire rated products meet the required classification. Valid fire-rated glass will also carry a permanent stamp or etching which is usually displayed in a corner which displays the manufacturer’s name, the testing standard and the specific rating, such as EI 60.
Is fire glass just tempered glass?
No, fire glass is not just tempered glass. While our systems often use tempered panes for structural strength, true fire-rated glazing involves a complex assembly of multiple layers and intumescent interlayers. These layers react to extreme heat by expanding and turning opaque to block flames and insulate against heat transfer. Standard tempered glass cannot provide this protection.
What is the difference between toughened glass and fire-rated glass?
The main difference between toughened glass and fire rated glass is their performance under extreme heat. Standard toughened glass is designed to shatter safely on impact but generally fails quickly in a fire, allowing heat to pass through it. Fire-rated glass acts as a barrier. It maintains ‘Integrity’ to stop flames and often ‘Insulation’ to block heat for a certified duration like 30, 60, 90 or 120 minutes.
What thickness is fire-rated glass?
The thickness of fire-rated glass varies significantly depending on the specific product and the level of protection required. For our systems, the glazing thickness typically falls into the following ranges:
- EI 30 ratings: often between 20 mm and 30 mm.
- EI 60 ratings: typically range from 25 mm to 50 mm.
- EI 90 ratings: generally between 40 mm and 60 mm.
- EI 120 ratings: can range from 50 mm up to 70 mm.
High-performance walls (like the MB-118EI): can accommodate glazing units from 31 mm up to 84 mm.
Is fire rated glass a legal requirement?
Fire-rated glass is a legal requirement for specific areas within UK buildings. Regulations like Approved Document B (England and Wales) mandate its use to protect escape routes and limit fire spread. Windows, doors and partitions forming part of a fire compartment must meet specific Integrity (E) and Insulation (I) ratings such as E30 or E60. This applies to both new builds and significant renovations. While the exact requirements depend on the location and function, the products must strictly adhere to British Standards like BS EN 1634.
How is fire rated glass tested?
Fire rated glass undergoes rigorous testing in a furnace following British and European standards like BS 476: Part 22 or the BS EN 1364 series. The glass and its framing system are exposed to temperatures exceeding 900°C. This process determines exactly how long the system maintains its integrity and, in the case of EI glass, its insulation properties.
Can any glass be fire rated?
No, not any glass can be fire rated. Standard glass will shatter in heat but fire-rated glass is specially engineered with materials like intumescent layers or wire mesh. These withstand extreme temperatures of 870°C+ and block flames or smoke for specific durations like 30, 60, 90 or 120 minutes. Even toughened safety glass is not sufficient as it generally acts only to resist thermal shock up to around 260°C. The different types of glass and key differences are:
- Standard Glass: Likely to break easily under fire heat.
- Toughened Glass (Safety Glass): Stronger but still only resists heat up to roughly 260°C. It is not rated for fire resistance.
- Fire-Rated Glass: Engineered for performance and meets specific building codes.
- Integrity (E-type): Stops flames and smoke (e.g. wired or laminated glass).
- Integrity & Insulation (EI-type): Prevents heat transfer too by using gel or intumescent layers
About The Author
Lauren Walker is the Managing Director of Aluminium Fire Systems. With over 10 years of experience in the fire rated glazing industry, Lauren works alongside architects and contractors to ensure complex projects meet the highest standards of fire safety. She is dedicated to bridging the gap between design aesthetics and strict compliance.