Clearly a barrier to fire

Clearly a barrier to fire

Wood, Mike

When alterations or refurbishments are being undertaken, ensuring the right fire– resistant glass is selected is crucial, both to assure safety and stay within the law. Mike Wood offers some points to consider.

Paradoxically, it is often easier to undertake a major refurbishment of premises than a minor alteration project. A large project will be handed to a larger contractor who will have the resources to manage every stage, including the correct specification and installation of materials. But what happens when relatively minor alterations are being made to a building, perhaps a new foyer or even partitioning for the rearrangement of a ward? Smaller contractors may be quicker and, with ever tightening budgets in mind, may be considerably cheaper.

The broad knowledge that the general and engineering managers of a hospital and other healthcare estates must have, by definition, will then come into play. But an area that, due to its considerable complexity, may not be fully understood is that of the specification and installation of the correct glass to comply with fire regulations; it is one of those areas that may not seem particularly exciting at first glance, but which may have a profound effect on the performance and, indeed, the legality of even a relatively minor installation.


Every hospital manager, care or facilities manager will, or should, be aware of their premises’ status regarding compliance with relevant fire safety regulations and local authority building registration. Such regulations impose fire safety requirements covering matters such as: means of escape, structural stability, fire-resistance of elements and structure, compartmentation to inhibit fire spread, reduction of spread of flame over surfaces, prevention of fire spread between buildings, and access for fire appliances and emergency services. Added to this now is the obligation on employers under the Fire Precautions (Workplace) Regulations 1997 to carry out, and continually review, a risk assessment of the building that they are responsible for, to ensure that employees are not placed at risk from fire.

In a larger refurbishment project, an architect will handle the specifications, but in a smaller job that role will often fall to the maintenance team or contractor. This means that the responsibility for getting it right is also often assumed to be that of the installer – that they will understand what is required and will call on the appropriate people for guidance on the more complex issues. After all, surely all that is required is some glass in the doors of the new partitioning? Often this is most certainly not so, and the use of inappropriate glass in such circumstances is wide– spread, if only through an ignorance of the subject.

However, the correct use of fire safety glass can make all the difference to protecting the people using the building in the event of fire – as well as complying with the appropriate regulations. There is a moral responsibility, as well as compelling legal reasons, for the managers to become at least broadly familiar with the use of fire resistant glass.


Within a hospital there exist further considerations, as many of the people within the facility will be disabled and bedridden, considerably complicating evacuation procedures. In parts of hospitals that are designed to be used by patients, and in similar accommodation such as nursing homes and homes for the elderly, the assumption of total evacuation of a building in quick time in the event of fire may even be inappropriate. It is also unrealistic to suppose that all patients will leave without assistance. In this and other ways the specialised nature of some health care premises demands a different approach to the provision of means of escape. A higher degree of fire protection built into the structure may be more appropriate than the case where occupants can move freely. NHS Estates has prepared guidance documents on safety and risk assessment in healthcare buildings, taking into account the particular characteristics of these buildings. These documents may also be used for non-NHS healthcare premises.

Guidance for new hospitals can be found in Firecode HTM 81 ‘Fire precautions in new hospitals’. Where work to existing hospitals is concerned, the guidance in the appropriate section of the relevant NHS Firecode can equally be followed. Attention is also drawn to the Home Office draft guide to fire precautions in existing residential care premises, which is under review.


Returning to the principles of fire resistant glass, the need for special glass comes from the fact that standard annealed glass cracks easily in a fire – and even toughened impact-resistant glass can fail under the fierce conditions created by a fire. A rapid rise to around 300 deg C, which can happen easily when plastics, fabrics and wall coverings burn, could cause toughened glass to shatter explosively, leaving nothing but a hole where the glass used to be.

Fire-resistant glasses, on the other hand, are manufactured to either prevent smoke and flames passing through or provide insulation against the heat as well — depending how they are rated. Those that provide a barrier against smoke and flames are called ‘integrity-only glasses’, while ‘insulation plus integrity’ glasses also protect against the intense heat of the fire.

Within these two categories there are a number of different types. A very common integrity glass is wired glass, such as Pilkington PyroshieldTM now established after many years’ of use, where the wire holds the glass together when it cracks to maintain the fire barrier.

Other integrity glasses can also incorporate a special fire– resistant layer between, and bonded to, the glass sheets, which reacts when the temperature rises, making it opaque (eg Pilkington PyrodurTM). Higher performing integrity with insulation glasses contain a number of such intumescent interlayers that ‘foam up’ to effectively block out the fire and both its radiated and conducted heat. These in effect act as an opaque insulating shutter. Such a fire– resistant glass is Pilkington PyrostopTM.

Where and when these different types of fire-resistant glass are used is laid down in the Building Regulations, Approved Document B – and specialist companies such as Pilkington operate help lines to aid with specification.

Document B provides the basic guidelines covering general building situations. It applies to new and altered buildings for England and Wales and is the key document referencing what is considered to be acceptable practice in providing fire protection measures for buildings. Scotland has slightly different reference regulations. Because the local fire authorities are responsible for applying the regulations, it is certainly advisable to involve Building Control as early as possible in the planning and approval process. It would also be a wise move to appoint a contractor who is a qualified installer of specialist fire resistant glass under the FIRAS scheme sponsored by the Glass and Glazing Federation and operated by Warrington Fire Research. Approved Document B draws reference to the value of such installer schemes as an acceptable way of demonstrating that best practice in installation has been followed.


One of the most important factors to bear in mind is that fire– resistant glass is not a stand– alone barrier to fire and smoke; it is installed as part of a fire rated system. This includes the glass, the frame, the glazing materials and the fixings.

When choosing a fire-rated system it is essential to use one that has a valid and relevant test report. This system can then only be installed exactly as approved in the formal report, because these are the conditions that it is safe to use it in, and any variation could easily lead to failure. Even apparently minor differences can make a big difference to the performance.


It is also very important to understand that fire-resistant glasses are certainly not all the same: what is achievable with one is not automatically achievable with another. Some carry certain framing requirements that can influence performance if not followed correctly. Others may be limited in terms of the maximum size at which they maintain their fire performance. Where fire safety is concerned, there can’t be any short cuts when lives are at risk, and reliability and consistency should be the watchwords. If in doubt, it’s best to follow the tried, tested and trusted route. After all, fire is dangerous and unpredictable.

The fact that one will encounter different behaviour in different fire-resistant glasses based on different technologies is simply common sense – different materials behave differently when they get hot. For example, hardwoods burn slower than softwoods, so this has a bearing on the size of the sections used for the frame to support the glass for the required period of time. Similarly, ordinary steel frames could warp significantly when they get hot, tending to bend and break the glass, so the construction of the frame has to accommodate this.

The really important thing though is not to allow an installer to stray from the specification laid down in the test report. Don’t change the size of the glass as the aspect ratio affects the performance. Don’t alter the design of the system; it has to be installed in the way that is recommended. And, most importantly, don’t change the glass to a different specification because, as I have pointed out, there are lots of different fire-resistant glasses that behave in different ways. And not all glasses offered for fire safety applications will enjoy full certification.


At the heart of all this advice is the moral as well as legal responsibility to protect the people in the building, including staff and especially patients. Get it wrong, use the wrong product, fail to provide a fire-rated system where one is required, and someone is going to come down on you like a ton of bricks. As the specifier, you could be subject to a charge of negligence, civil liability or even criminal liability in the event of people being injured as a result of the wrong fire system being used.

Fire safety is high on the Government’s agenda. The Home Office has stated the Government’s intention to reinforce and reform fire safety regulation, at the same time making it simpler. They draw attention to the activities of the new Fire Safety Advisory Board and to the original consultation document in 1997 that placed a general duty of care on employers and owners and occupiers of almost all buildings except private dwellings to provide and maintain adequate fire precautions. In this context, the particular benefits of installing fire-resistant glass is clear: once the right product is installed, in the right place, in the right system and in the right way then it is there permanently, requiring no ongoing maintenance to ensure its proper functioning when called upon to do so.

But it is not being melodramatic to encourage you to consider the personal issues of injury or even loss of life in the event of a serious fire, if proven that incorrect specification of an installation was to blame. Such occurrences are thankfully rare, but they do happen, or regulations would not exist to provide protection against them.

Because of all these considerations, it really does make sense to be aware of the issues, and to ensure that the correct products are used. If you have doubts concerning how and where to use fire resistant glasses then contact Pilkington and we will be pleased to help with specialist advice.

Mike Wood is global head of marketing of Fire Resistant Glasses at Pilkington.

Copyright Wilmington Publishing Ltd. Jul 2001

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