Guide to Fire Rated Window Frames for Safety

This is where fire rated window frames, also known as fire resistant window frames or fire window frames, play a vital role. These specialized windows are designed to withstand fire for periods ranging from 30 to 120 minutes, depending on their rating. Constructed from fire-resistant materials such as steel, aluminum, or specially treated timber, fire rated window frames are tested to meet stringent standards, ensuring they can contain fire and smoke effectively. In this comprehensive guide, we’ll explore what fire rated window frames are, how they are tested, the types available, their benefits, and how they align with UK building regulations. We’ll also provide practical tips for selecting and maintaining these essential safety features.

What Are Fire Rated Window Frames?

Fire rated window frames are windows engineered to resist fire for a specified duration, forming a crucial part of a building’s passive fire protection system. Unlike standard windows, which may shatter or fail under high temperatures, fire resistant window frames are designed to prevent the spread of flames and smoke while maintaining structural integrity. They are often referred to as fire window frames due to their ability to withstand fire exposure.

These frames are typically made from robust materials like steel or aluminum, though some use timber treated with fire-retardant coatings. The glass used in fire rated window frames is equally important, often consisting of wired glass, ceramic glass, or multi-layered fire-resistant glass designed to resist shattering or melting under intense heat. The fire rating, expressed in minutes (e.g., 30, 45, 60, 90, or 120), indicates how long the window can maintain its integrity and prevent the passage of fire and smoke.

The fire rating applies to the entire window assembly, meaning both the frame and glass must meet the required standards. For example, a 60-minute fire rated window frame ensures that both components can withstand fire for at least an hour, providing critical time for evacuation and firefighting efforts.

How Are Fire Rated Window Frames Tested and Rated?

To ensure reliability, fire rated window frames undergo rigorous testing to meet industry standards. In the UK, these tests are typically conducted in accordance with British Standard BS 476 Part 22 or European standards like BS EN 1634-1. Internationally, standards such as UL 9 or ASTM E119 may also apply, depending on the project requirements.

During testing, the window assembly is exposed to a controlled fire in a furnace, and its performance is evaluated based on key criteria:

• Integrity (E): The ability to prevent flames and hot gases from passing through.
• Insulation (I): The capacity to limit temperature rise on the non-fire side, reducing heat transfer.

For windows, ratings are often expressed as E followed by the duration in minutes, such as E 30 for 30 minutes of integrity. If insulation is required, the rating might be EI 30, indicating both integrity and insulation for 30 minutes. The testing process involves mounting the window in a test rig and subjecting it to fire from one side. The window must maintain its integrity without allowing flames or hot gases to penetrate for the specified duration.

Certified fire rated window frames are labeled with their fire rating, enabling architects and builders to select products that comply with building regulations. These tests ensure that fire window frames perform reliably in real-world fire scenarios, providing peace of mind for building owners and occupants.

Types of Fire Rated Window Frames

Fire rated window frames are available in various styles to meet diverse architectural and functional needs. Below are some common types, each designed to balance safety with practicality:

1. Fixed Window.: These non-operable windows are ideal for areas where ventilation is not needed but fire protection is essential. Fixed fire window frames maximize light transmission while maintaining fire resistance, often used in commercial or high-risk residential settings.
   
2. Casement Windows. Hinged on the side, casement fire rated window frames open outward, offering full ventilation. They are designed to meet fire rating standards while providing operability, making them suitable for spaces requiring both safety and airflow.
   
3. Single-Hung Windows. These windows feature a movable bottom sash and a fixed upper sash, allowing ventilation through the lower section. Single-hung fire resistant window frames are popular in residential buildings where partial operability is desired.
   
4. Horizontal Slider Windows. With sashes that move left or right, these fire window frames offer a modern aesthetic and smooth operation. They are ideal for contemporary designs requiring fire safety.
   
5. Awning Windows. Hinged at the top, awning fire rated window frames open outward from the bottom, providing ventilation even during light rain. They are versatile for various building types.

Each type can be manufactured to achieve specific fire ratings, ensuring that fire resistant window frames meet the necessary safety standards without compromising design or functionality. When choosing a type, consider the building’s layout, ventilation needs, and aesthetic preferences.

Benefits of Installing Fire Rated Window Frames

Investing in fire rated window frames offers numerous advantages, making them a critical component of modern building design:

1. Enhanced Safety. Fire window frames contain fire and smoke, providing occupants with additional time to evacuate safely. This is particularly crucial in high-occupancy buildings like schools or offices.
   
2. Property Protection. By preventing fire spread, fire resistant window frames reduce damage to the building and adjacent structures, minimizing repair costs.
   
3. Regulatory Compliance. Fire rated window frames ensure compliance with UK building regulations, such as Approved Document B, avoiding legal issues and ensuring safety standards are met.
   
4. Insurance Savings. Some insurers offer reduced premiums for buildings equipped with fire safety features like fire window frames, recognizing their role in risk reduction.
   
5. Aesthetic Versatility. Modern fire rated window frames are designed to blend seamlessly with various architectural styles, maintaining visual appeal without sacrificing safety.
   
6. Additional Features. Many fire resistant window frames provide benefits like sound insulation, energy efficiency, and enhanced security, adding value beyond fire protection.

By incorporating fire rated window frames, building owners can enhance safety, protect investments, and meet regulatory requirements while maintaining design flexibility.

Compliance with UK Building Regulations

In the UK, fire safety is governed by the Building Regulations, specifically Approved Document B (Fire Safety). Volume 1 addresses dwellings, while Volume 2 covers other buildings. For windows, Approved Document B outlines two key requirements:

1. Emergency Escape. Windows in habitable rooms, particularly those above ground level, may need to serve as emergency escape routes. According to Approved Document B, Volume 1, paragraph 2.10, escape windows must have a minimum clear opening of 0.33 square meters, with at least 450mm in height and width, and be easily operable without a key. This ensures occupants can exit safely during a fire.
2. Fire Resistance. Windows in fire-resisting walls or near property boundaries may need to be fire rated to prevent fire spread. These fire window frames must achieve at least E 30 integrity, meaning they can withstand fire for 30 minutes without allowing flames or hot gases to pass through. In some cases, insulation (EI 30) may also be required to limit heat transfer.

Fire rated window frames that meet these standards help ensure compliance with UK regulations, providing both safety and legal assurance. For detailed guidance, refer to Approved Document B.

Choosing the Right Fire Rated Window Frames

Selecting the appropriate fire rated window frames requires careful consideration of several factors:

1. Fire Rating. Determine the required fire rating (e.g., E 30, EI 60) based on the building’s design, location, and regulatory requirements.
2. Window Type. Choose a style (fixed, casement, slider, etc.) that aligns with the building’s functional and aesthetic needs.
3. Material. Options include steel, aluminum, or fire-treated timber. Steel offers durability, while aluminum provides a sleek, modern look. Timber can be used for heritage properties with appropriate treatments.
4. Glass Type. The glass must match the frame’s fire rating. Common options include wired glass, ceramic glass, or advanced multi-layered fire-resistant glass like Pyrostop.
5. Aesthetic Preferences. Many manufacturers offer customizable fire window frames to match specific design requirements, ensuring safety doesn’t compromise style.
6. Budget. While fire resistant window frames may be more expensive than standard windows, their safety benefits justify the investment. Compare options to balance cost and performance.

Consulting with architects, builders, or fire safety experts is recommended to ensure the selected fire rated window frames meet project-specific needs and comply with regulations.

Installation and Maintenance Tips

Proper installation and maintenance are critical to ensuring fire rated window frames perform effectively during a fire.

Installation

• Professional Installation. Engage qualified professionals familiar with fire rated assemblies to ensure compliance with manufacturer specifications and building regulations.
• Correct Fitting. Verify that all components (frame, glass, seals) are properly installed and sealed to maintain the fire rating.
• Compliance Check. Ensure installation aligns with standards like BS 476 Part 22 or BS EN 1634-1.

Maintenance

• Regular Inspections. Check for damage, such as cracks in the glass or worn seals, that could compromise fire resistance.
• Operability. For operable fire window frames, ensure smooth operation and test automatic closure devices (if present) regularly.
• Cleaning. Use non-damaging cleaning methods to preserve fire-resistant materials.
• Repairs: Use only approved materials and methods for repairs to maintain the fire rating.

By adhering to these practices, fire resistant window frames will remain effective throughout their lifespan, providing reliable protection.

Conclusion

Fire rated window frames are an essential component of a building’s fire safety strategy, offering critical protection by containing fire and smoke. By understanding their design, testing standards, types, and benefits, building owners and designers can make informed decisions to enhance safety and comply with UK regulations. Whether referred to as fire resistant window frames or fire window frames, these products provide peace of mind, protect property, and ensure compliance with standards like Approved Document B.At FireResist, we offer a wide range of fire rated window frames designed to meet the highest safety and performance standards. From fixed to operable windows, our solutions combine robust fire protection with aesthetic versatility. Contact us today to explore how our fire window frames can enhance your building’s safety and design.