Choosing the Right Glass for Fire Doors

Experts estimate that a properly installed fire door can contain a fire for 30 minutes or more, providing critical time for evacuation and emergency response. Increasingly, architects and builders are incorporating glass for fire doors to combine safety with aesthetic benefits like natural light and visibility. However, glass for fireproof doors must meet rigorous safety standards to perform effectively during a fire. This article explores the role of fire rated glass doors, the UK regulations governing their use, the types of glass for fire doors available, and how to choose and maintain them for optimal safety and design.

The Importance of Glass in Fire Doors

Using glass for fire doors offers significant advantages, making glass fire doors a popular choice in modern buildings. One key benefit is visibility, which enhances safety in environments like schools, offices, or hospitals by allowing occupants to monitor movement through doorways. For example, in a busy office, a fire rated door with glass can help staff observe activity in adjacent areas, improving security without compromising safety. Additionally, glass for fire doors allows natural light to flow through spaces, reducing the need for artificial lighting and creating a brighter, more welcoming atmosphere compared to solid fire doors.

However, standard glass shatters at around 120°C, making it unsuitable for fire doors. Fire rated glass for doors is engineered to withstand extreme heat, maintaining structural integrity and, in some cases, limiting heat transfer. This ensures that fireproof glass doors not only meet safety requirements but also enhance the overall design of a building. According to recent surveys, 75% of fire doors in the UK fail to meet safety standards, often due to incorrect installation or maintenance, underscoring the importance of choosing the right glass for fire doors and ensuring proper installation.

UK Regulations

In the UK, fire rated door glass requirements are outlined in Approved Document B of the Building Regulations, which governs fire safety for both residential and commercial buildings. This regulation ensures that all components of a fire door, including glass for fire doors, meet specific performance standards. The glass must be certified to British Standards such as BS EN 12150 for toughened glass and BS EN 1634 for fire resistance testing. These standards verify that fire rated glass for doors can withstand fire exposure for a designated period, typically measured in minutes, such as E30 (30 minutes of integrity) or EI60 (60 minutes of integrity and insulation).

The fire rating of glass determines its performance. Integrity-only glass (E) prevents the passage of flames and hot gases but does not limit heat transfer. In contrast, glass with both integrity and insulation (EI) restricts temperature rise on the non-fire side to an average of 140°C and a maximum of 180°C, offering greater protection. According to Approved Document B, if glass only provides integrity, its use is restricted. For instance, in protected stairways, glazing in walls is unrestricted above 1100mm from the floor, and door leaves can have unlimited glazing. However, glass for fire rated doors that meets both integrity and insulation criteria faces no size restrictions, providing architects with greater design flexibility for fire rated glass doors.

The Glass and Glazing Federation emphasizes the importance of proper labeling, requiring the manufacturer and product name to be visible on glass for fire doors for traceability and compliance. Vision panels are also mandated in specific scenarios, such as doors on escape routes that subdivide corridors or swing both ways, to enhance safety and accessibility, aligning with Approved Document M.

Types of Fire-Rated Glass for Fire Rated Doors

With various types of fire rated glass for doors available, understanding their properties is essential for making an informed choice. Each type offers unique benefits and is suited to different applications based on fire resistance, aesthetics, and cost.

Wired Glass

Wired glass is a traditional option for glass fire doors, featuring a wire mesh embedded within the glass to hold it together during fire exposure. It typically provides 30 to 60 minutes of fire resistance (E30 or E60), making it suitable for many standard applications. Its primary advantage is affordability, making it a popular choice for budget-conscious projects, such as industrial facilities. However, the visible wire mesh can detract from aesthetics, and its impact resistance is lower than other options, limiting its use in high-traffic areas.

Ceramic Glass

Ceramic glass, such as FireLite, is a clear, wireless alternative that offers fire ratings from 20 minutes to 3 hours. Its transparency and high impact resistance, meeting standards like ANSI Z97.1, make it ideal for environments where aesthetics are a priority, such as modern offices or educational institutions. While more expensive than wired glass, ceramic glass provides a sleek, modern look and superior durability, making it a preferred choice for high-end architectural designs requiring fire rated glass doors.

Intumescent Laminated Glass

Intumescent laminated glass consists of multiple layers with interlayers that expand when exposed to heat, providing both integrity and insulation (EI ratings). This type of glass for fire doors is particularly valuable in high-risk areas where limiting heat transfer is critical, such as in commercial buildings with large glass panels. Because it meets EI criteria, it faces no size restrictions under Approved Document B, offering significant design flexibility. However, its higher cost and complex manufacturing process make it a premium option.

Specially Tempered Glass

Specially tempered glass provides some fire resistance but is less robust than other types, often failing to withstand higher fire ratings or thermal shock tests like the hose stream test. It is typically used in applications with lower fire rating requirements, such as non-critical areas. While cost-effective, its limitations make it less common in high-stakes environments requiring fireproof glass doors.

How Fire-Rated Glass is Tested

To ensure reliability, fire rated glass for doors undergoes rigorous testing under standards like BS EN 1634. The process involves placing the glass in a frame and exposing it to a controlled fire in a furnace to simulate real-world conditions. For integrity (E) ratings, testers check that the glass prevents flames and hot gases from passing through for the specified duration. For insulation (EI) ratings, the glass must also limit temperature rise on the non-fire side to protect against heat-related injuries or ignition of nearby materials.

In some cases, particularly for ratings above 45 minutes, a hose stream test is conducted, where the glass is sprayed with water from a fire hose after fire exposure to assess its resistance to thermal shock. Only glass certified by accredited laboratories, such as those recognized by the British Standards Institution (BSI), should be used in fire rated glass doors to guarantee performance and compliance.

Choosing the Right Glass for Fire Doors

Selecting the appropriate glass requires careful consideration of several factors:

• Fire Rating Needs. Assess the required fire resistance based on the door’s location and the building’s fire safety plan. High-risk areas, such as escape routes, may require EI-rated glass for fire doors to limit heat transfer.
• Aesthetic Goals. For spaces where appearance matters, ceramic or intumescent laminated glass offers clearer, more modern visuals compared to wired glass, enhancing the appeal of glass fire doors.
• Impact Safety. In high-traffic areas, ensure the glass meets impact safety standards like ANSI Z97.1 to prevent injuries from accidental collisions.
• Size and Design. Intumescent laminated glass is ideal for larger panels due to its unrestricted size allowances under UK regulations, making it suitable for fire rated glass doors in expansive designs.
• Budget Constraints. Wired glass is the most economical, while ceramic and intumescent options are pricier but offer enhanced performance and aesthetics for fireproof glass doors.

Always verify that the glass carries certifications like the CE mark or BSI approval to ensure it meets fire rated door glass requirements. Using non-compliant glass can lead to regulatory violations and, more critically, compromise safety during a fire.

Installation and Maintenance of Fire-Rated Glass Doors

The effectiveness of fire rated glass doors depends heavily on proper installation. The glass for fire doors must be part of an approved glazing system, including certified frames, seals, and fixings, all tested together to ensure cohesive performance during a fire. For example, systems like the MB-78EI use intumescent materials and are compatible with tempered glass, ensuring robust fire resistance (EI30 or EI60). Professional installation by experts familiar with fire safety standards is essential to maintain the door’s integrity, with minimal gaps (2–4 mm) between the door and frame to prevent smoke leakage.

Regular maintenance is equally important to ensure long-term performance of glass fire doors. Building owners should conduct routine inspections to check for cracks, dents, or seal deterioration. Self-closing mechanisms must function correctly, and fire safety signage, such as “Fire door keep shut,” should remain visible, as required by BS 5499-5:2002. The Regulatory Reform (Fire Safety) Order 2005 mandates that a “responsible person” (e.g., a building manager) oversees these checks to maintain compliance.

Benefits of Glass in Fire Doors

Incorporating glass for fire doors offers several advantages beyond fire safety. Visibility is a key benefit, allowing occupants to assess conditions on the other side of a door during an emergency, such as checking for smoke or fire. This is particularly valuable in settings like schools or hospitals, where quick decision-making is critical. Additionally, glass fire doors allow natural light to penetrate deeper into buildings, reducing energy costs and creating a more pleasant environment. From a design perspective, fire rated glass doors enhance the aesthetic appeal of modern spaces, aligning with architectural trends favoring open, light-filled areas.

Common Mistakes to Avoid

When selecting or installing glass for fireproof doors, avoid these common pitfalls:

• Choosing Non-Certified Glass. Always use glass certified to meet fire resistance standards to avoid safety and legal issues.
• Incorrect Installation. Using incompatible frames or seals can compromise the performance of fire rated glass doors.
• Neglecting Maintenance. Regular inspections are essential to ensure a fire rated door with glass remains effective.
• Ignoring Impact Safety. In high-traffic areas, ensure the glass meets impact safety standards to prevent injuries.

By addressing these issues, you can ensure that your fireproof glass doors perform as intended during an emergency.

Conclusion

Choosing the right glass for fire doors is a critical decision that balances safety, compliance, and aesthetics. By understanding the types of fire rated glass for doors, adhering to UK regulations like Approved Document B, and prioritizing professional installation and maintenance, you can enhance the safety and appeal of your building. Whether you need cost-effective wired glass or high-performance intumescent laminated glass for fire rated glass doors, FireResist offers a range of solutions to meet your needs.