What is fire rated glazing and what are the design options?

Fire Rated Glass (which is often referred to as fire-resistant glass) is a specialist glazing product that has been developed to provide a period of protection during a fire. There are many different types of glass that offer various benefits, therefore it’s important to understand how to choose the correct glass for your project.

Float glass offers very little fire protection (it tends to break at 120°C) which wouldn’t last very long in a fire. Toughened glass or tempered glass lasts slightly longer than float glass – it will withstand heat of up to about 260°C. However, to be fire-rated the glass must be capable of withstanding temperatures in excess of 870°C.

Is toughened glass fire rated?

No, standard toughened glass isn’t manufactured to withstand the high temperatures required to resist the thermal shock produced in a fire – therefore toughened glass should not be used in locations where fire-resistant glazing is required.

Fire-rated doors are a requirement in certain buildings, often buildings with high volumes of people traffic, to help slow down the spread of fire from one area to another and to help maintain a safe exit route for the building’s occupants. Every fireproof glass door is therefore required to act as a barrier to the passage of smoke and/or fire to varying degrees depending on the location of the door and the fire hazards associated with that building.

Why are fire resistant doors needed?

If you are designing a new build home or renovating an existing property that is over three storeys (this includes loft conversions) then fire rated doors will be required to separate the stairwell and every habitable room located off the stairwell. Fire-rated doors in the home are also required in a two-storey residential property that has a door leading from a garage to the main house.

The purpose of fire-rated glazing is to protect exit ways from a building for a pre-prescribed amount of time to ensure that everyone can escape safely in the event of a fire. These fire-rated glass systems also help to slow down the process of fires spreading throughout the building, thus provide the fire service with slightly more time to attend the fire before it spreads further.

Fully glazed fire doors offer the benefits of fire protection while maintaining the travel of light through areas of a building, resulting in the feeling of a more light and open living space even though they are compartmentalised.

How does fire rated glazing work?

IQ Glass use a transparent fire rated glass to ensure these systems are aesthetically cohesive with our other glazing products. The fire-rated glass IQ uses is manufactured from layers of toughened glass interspersed by intumescent layers.

In the instance of a fire, the heat from the fire will cause the outer layer of the glass to break – however, the broken pane will be held in place by the intumescent layer. These layers then rapidly swell to provide insulation – this reduces the level of heat from the fire radiating through into the surrounding rooms and also helps to stop smoke from travelling through the opening and into the protected fire exit routes. Some fire-rated glass intumescent layers turn opaque in the heat of a fire which stops vision through the glass – this can help to reduce the level of panic when leaving the building.

 

steel framed fire rated internal door
fire rated glazing solution

What do I need to consider when specifying fire rated glazing?

When looking at a fire rated glazing system, both the framing and the glass much be taken into consideration. With fire rated glazing you cannot deviate away from the test evidence and what has been certified. It is imperative that the fire rating classifications are paid strict attention to as this is the test evidence that demonstrates the ability of each system.

Fire rated glazing is categorised by the amount of time it provides protection for under the effects of a fire. There are various levels of fire rated glass – it is important to be aware of what fire rating is required. Building Regulations Part B offers a lot of guidance about where fire rated systems or products will be needed. Fire rating requirements will depend on the exit routes available for occupants and in the type of building and its use.

Does glass have a fire rating and how is it classified?

Fire rated glass is classified by the amount of time it provides for integrity and insulation. These categories are highlighted by the following:

The Integrity Period

The integrity rating of fire rated glazing is the amount of time the glass will remain in situ in its frame/fixings under the effects of fire. This also denotes the glass's ability to prevent the passage of flames and hot gasses through the glass when exposed to fire on one side.

The Insulation Period

The amount of time the glass will act as an effective barrier against flames, heat and smoke under the effects of fire. When tested, the glazing must limit the temperature on the non-fire side of the glazing to no more than an average of 140C and no more than 180C in any single position.

The above categories are also split into the duration of protection the glass provides for Integrity and Insulation. These fire protective levels are broken down into E classifications to denote its performance.

E = glass with an integrity only rating

El = glass with an integrity and insulation rating

EW = glass with an integrity rating and a degree of heat resistance.

Read more about the different levels of fire resistance categories here: https://technical.iqglassuk.com/technical-terms/fire-rated-glazing/

 

Can fire rated glass installations be frameless?

Frameless fire-rated glass is possible, however, to ensure the integrity of the system a timber frame surrounding the glass needs to be recessed within the wall to support the glass unit in the instance of a fire.

Frameless fire-rated glazing is only suitable for internal use and cannot be installed to swimming pool environments. The environment of an indoor swimming pool is aggressive due to the temperature, humidity in the air and the chemicals added to the water. In these environments, the atmosphere attacks the TPS surrounding the frameless glazing, thus damaging the performance of the frameless fire rated system.

When structural glazing is installed with glass to glass joints, a thermoplastic spacer (TPS) is introduced down the edge of the glass, which is silicone. The TPS is approximately 10-12m with a 68m black silicone joint. This means that where there is a glass to glass joint, there will be a nominal 26-32mm black silicone join running the height of the frameless fire glass.

Frameless internal windows and doors can both be manufactured with fire rated properties; the modern frameless glazing provides a contemporary aesthetic to a traditionally cumbersome element of a building. Internal fire rated windows are beautiful additions to interior designs as they offer no obstruction to light within the building while offering robust fire protective properties. Interior glazed fire doors can be designed as a single or double fireproof pivot door system with a contemporary, minimal aesthetic. This glazed fire door system is the perfect solution to maintain modern interior design properties where fire rated performance is required.

Why do the frameless glass doorsets have a slim black line running along the edges of the glass?

The frameless fire rated interior door systems have a visible back-painted band surrounding the edge of the glass. The small black edge around each opening door is the only profile that you will see, which creates a neat finish to the edge of the door; this back-painted area hides the intumescent seal of the fire rated glass.

What TPS colours are available?

IQ is often asked whether there are any other colour options available for the TPS (Thermo Plastic Spacer) - for fire rated glazing the only colour option for the TPS is black.

Can fire rated glazing be insulated?

Most fully glazed fire doors can be incorporated into a Double Glazed Unit (DGU) or a Triple Glazed Unit (TGU) as required. The desire for an insulated system could either be for acoustic insulation or thermal insulation - speak to a member of the IQ technical team to specify insulated fire-rated systems.

frameless fire rated glass door

FAQ about Fire Rated Glazing

What fire-rated systems do IQ offer?

IQ Glass offers a broad selection of fire-rated glass solutions including framing, fire-rated glazing and installation. The range includes Mondrian® Fire Doors (steel fire rated doors), frameless fire-rated doors, fire rated glass floors and steel fire screens/steel fire rated glass partitions.

Can I have a steel look fire-rated glazing system?

IQ offer both steel framed fire rated glass doors and screens for an Art Deco style system. The steel-framed fire rated doors can also be integrated within a steel framed fire rated glass façade design for a larger steel-framed glazing arrangement.

The steel-framed glazing systems must be specifically designed to be used as a fire-resistant glazed system. IQ Glass have various steel framed fire rated glazing systems with a choice of applied glazing bars or glazing bar aesthetics created using a specialist ceramic frit technique.

Can any lock be fitted onto a fire rated door?

The locking and handle mechanism for a fire rated door system must also be fire rated. Metal gets extremely hot in the event of a fire and it can quickly go from being an incredibly strong component to the weakest element of the door system. Therefore, it is important that the locking and handles are fully certified for fire safety.

 

Rebecca Clayton
Technical Sales
Rebecca is Head of Marketing at the IQ Group and has worked in glazing specification for many years. She has a broad range of technical knowledge about all our glazing products and offers technical advice and guidance to architects for specification. Her easy to digest technical advice is often quoted in magazines and publications. You might also recognise her as one of the IQ Glass CPD presenters.
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