The Importance of Fire Rated Glass in Building Design

fire rated glass

What is Fire Rated Glass?

Fire rated glass (a.k.a. fire resistant safety glass) offers a period of protection from smoke and flame, in the event of a fire. The level of protection depends on the specific type of glass deployed but all fire rated glass acts as a barrier that stops flames and smoke from spreading through buildings when they are on fire. Different to standard safety glass, although offering some of the same high strength properties, fire rated glass has been rigorously tested to ensure it can withstand the temperatures reached during a fire and offer effective protection for a stated period of time. Designers and architects are increasingly turning to fire rated glass in their building designs, as it enables them to maximise more natural light and create more open and connected interiors, while also ensuring the health and safety of the people inside.

Fire Ratings Explained

Fire Resistance Tests are carried out by independent companies and the resulting official Fire Protection Rating is linked to strict parameters covering the size, frame and installation materials used. You should always make sure the intended installation matches these parameters, otherwise the Fire Protection Rating will be invalid.

The level of protection offered is given in periods of time, starting with 30 minutes. The period of protection is called the ‘integrity period’ and basically means the length of time the glass will remain in its frame and be able to effectively block smoke and flames from spreading. The integrity period is classified using the letter ‘E’, followed by the period of protection offered – e.g. E60 = 60 minutes integrity.

Some fire rated glass also offers heat insulation that acts as a barrier against the heat produced by fire. This ‘insulation period’ is the length of time the glass will limit the temperature, on the side without the fire, to no more than an average temperature of 140°C, or 180°C at any single point. Designated by the letter ‘I’ and appearing after the integrity period, it also uses increments of 30 minutes to indicate the level of protection offered – e.g. EI 60/30 = 60mins integrity and 30mins insulation.

Some glass may have the rating EW, which essentially means that there is a degree of heat resistance provided but for no discernible time period, unlike EI rated glass.

Where Fire Rated Glass must be used:

Below is an overview of four areas where all glass used must be fire rated. For complete details of fire safety building regulations, see the full statutory guidance on the government website.

Fire Escapes

Building regulations provide strict guidelines for the periods of protection required for each element of a building’s escape route. Modifications to the structure or layout will need to factor in any updated requirements. For example; if a balcony or flat roof will form part of the escape route, the entire route, including its structure and any opening within 3m, should offer 30 minutes of fire resistance. Access to exit stairways and the stairways themselves also need protection from fire using fire rated glass doors and frames, as well as fire rated glass walls. This is especially important for projects like loft conversions, where access is often completely unprotected to begin with.

Prevent fire spread in the lining

The materials used for the internal lining of a building can significantly contribute to fire growth, both in terms of the fire’s ability to spread across their surface and the amount of heat released during their combustion. Fire rated glass panels with an EI rating can prove to be a critical barrier that prevents damage and injury, when fire is spreading through a building.

Stop fire spreading to the structure

Fire rated glass should be used as part of a system to confine a fire to the room it originated in, without it spreading to other rooms or the building structure, for as long as possible. Fire rated glass partititions will slow down the spread of fire, without creating a claustrophobic atmosphere. It would not be sufficient to use tempered glass with a sprinkler system, as tempered glass is prone to shatter when exposed to water in high temperature environments. Building Regulations differ for dwellinghouses and other buildings but the highest requirement for fire resistance is 120 minutes of both integrity and insulation.

Resist external fire spread

External walls and roofs in commercial buildings are legally required to resist the spread of flames over their surface, to prevent the spread of fire from building to building. Unlike more traditional external building materials, fire rated glass walls are a non-combustible material, meaning they offer enhanced protection against the spread of fire.  Fire rated glass windows are also vital to containing fire and stopping it escaping or entering a property. Any windows in an external wall could be considered unprotected, if they are not made from appropriate fire rated glass.

Fire resistant safety glass is a key component of modern building design, not just in terms of health and safety but also in harnessing the benefits of increased light, openness and visibility. If you are working on a project that could benefit from incorporating fire resistant glass, download the Diamond Glass Fire Glass brochure or get in touch, if you have any specific questions.


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