As architectural design values have evolved, glass has remained one of the most ubiquitous construction materials. What has not changed, however, is that a building has a fundamental duty to protect the people and possessions within it.
The recent fire at Glasgow School of Art’s Mackintosh building in Scotland has highlighted the challenges in not only protecting individuals, but avoiding potential damage and expensive repair costs, which in this case is estimated to be in excess of £20 million.
In the event of a fire, specialist glazing solutions can play a pivotal role in protecting individuals by preventing the spread of smoke and flames. While fire-resistant glazing has become a crucial component of modern design and construction, retrofitting these systems in older properties has sometimes been perceived as troublesome, given the need to preserve a building’s character.
What is Fire-Resistant Glazing?
Fire-resistant glass can not only help protect the integrity of a structure, buying those inside it vital time in which to exit the building, it can also help preserve valuable contents, like company records, artwork or historical artefacts.
One of the reasons that fire-resistant glass is used more frequently in contemporary building construction is because of its ability to combine safety and protection properties with appealing aesthetics and the performance features of modern glazing, such as low-emissivity, noise reduction, solar control or safety ratings; all of which provide solutions to key demands in today’s market.
Irrespective of the age of the building, using fire-resistant glazing can allow for these benefits to be incorporated into the existing building, and also offer the required level of fire protection.
The Advent of Fire Safety
There remains a key focus and attention on fire safety since the UK’s Regulatory Reform (Fire Safety) Order 2005. Since then, building owners and operators are responsible for ensuring that appropriate fire precautions and protection measures are in place. Building regulations also place responsibility on those who carry out the work.
As well as holding building owners to account for the welfare of occupants, the Reform has helped to instil best practice at each stage of the design and construction process. This applies to risk assessors, building engineers, suppliers, installers and, of course, manufacturers, all of whom must play their part by producing and specifying the safest solution for the installation.
Why Specify Fire-Resistant Glazing?
The key function of fire-resistant glazing is to allow the safe escape of building occupants, while allowing unhindered access for rescue crews. Fire-resistant glazing physically separates people and valuable objects from flames, smoke, heat and other products of combustion, which is critical for safe egress.
While providing a level of protection, fire-resistant glazing can be more aesthetically pleasing than traditional solid walls because of the advantages of transparency provided by glass as it allows light into the body of the building.
Containing the fire as much as possible can help limit damage to the building as well as any adjoining structures, which can reduce need for remedial works. Needless to say, rebuilding and refurbishing a building with fire damage is a time-consuming and expensive task. If a fire is not contained, it can cause the integrity of the structure to be compromised, resulting in partial or complete collapse. This can have costly, and more importantly, fatal consequences.
Integrity & Insulation
One of the most fundamental, and yet often-overlooked, aspects of installing fire-resistant glass is that it must be used as part of a fully qualified fire-rated system. All parts of the unit – including the glass, the glazing seal, beading, fixings and the frame itself – must be compatible under fire conditions, and its performance must be referenced to appropriate and relevant test evidence.
Fire-resistance performance is defined by two categories:
- The first is the level of integrity that the glass can provide; this is measured by a function of time. The tested system must contain the fire and also protect from sustained flaming on the non-fire side. Products are subjected to a standard time/temperature curve according to either British Standard BS 476-Part 20-22 or European standard EN1363 series. Depending on performance in these tests, the products are classified to the attained test time 30, 60, 90, 120 and even 180 minutes.
- The second category is insulation; this assesses the glass’ ability to prevent significant heat transfer from the flames on to the non-fire side, with the non-fire side face not exceeding an average temperature of 160°C. This type of performance is beneficial for use in stairwells and access corridors, for example, as these need to be kept as cool as possible in order to create a safe access and exit route for occupants and firefighters.
Our understanding of glass’ behaviour in fire, as well as advances in glass technology, has led to the development of some innovative fire-resistant glazing solutions. Unlike fire-rated glass products of the past, such as wired-glass, modern products are completely transparent and therefore more aesthetically appealing.
Some maintain this transparent appearance during a fire, while others use intumescent interlayer technology to create an opaque insulating barrier for added protection. This is particularly effective because it reacts with the flames and heat and turns the glass white. The benefit of this is two-fold: firefighters are better able to determine the location of the fire quickly and efficiently, and the insulating properties of the glass means that the space on the other side of fire is cool enough to use as an easy and safe means of escape by possibly disorientated occupants. There is also the additional potential benefit of reducing panic during evacuation by masking the true extent of the fire.
Case Study:
The Swiss Church
In 2009, The Swiss Church Grade II listed building underwent a £2 million renovation and modernisation. A key part of the brief was to maintain the original character of the property.
The beautiful structure, built in 1775 in the heart of London’s Covent Garden, illustrates how fire-resistant glazing can be incorporated into an important historical building, improving performance without dramatically altering its appearance. The refurbishment included repairs to the façade, internal modifications and new windows. Fire-rated glazing was specified for all the glass replaced during the project in order to provide greater levels of fire protection.
The fire-rated system installed provides 30-minute integrity and insulation in case of fire. The glass also provided an unobtrusive way of extending the focal point of the building, the central hall.
Fire-Rated Glazing in Heritage Settings
While the benefits of fire-resistant glass solutions have long been appreciated in new-build settings, there is now a growing recognition of the need to install such products in existing, heritage and historical buildings.
Here lies the challenge of bringing these buildings in line with the latest fire safety practices without compromising their essential character, aesthetics and functionality. The use of fire-resistant glass in such properties enables the preservation and protection of the old, while gaining the benefit of modern fire-resistant technology. This is all possible while enhancing the security of the building, and improving its energy performance and carbon footprint.
Contractors and installers can run into difficulties when retrofitting older buildings because there are some who are opposed to the installation of new materials not true to the era or architectural style of the original structure. However, the benefits of doing so can make the difference between a building being damaged beyond repair and a fire being contained effectively. This can prevent Listed or Graded buildings being lost forever, and affords owners the opportunity to save and restore them to their former glory.
Where modern buildings benefit from the added protection of devices such as water sprinkler systems, it can be challenging and disruptive to install these into centuries-old structures. Fitting unobtrusive, transparent fire-resistant glass in internal partitions and door panels offers a simple and effective solution to balancing character integrity with fire safety.
Key Advice
Here is some key advice when specifying fire-resistant glass in order to achieve maximum protection and performance:
- Specifiers, architects, contractors and installers must work together to confirm the level and type of fire resistance required – some systems offer integrity only, others both integrity and insulation.
- When installing fire-resistant glazing in large buildings with lots of visitors, such as museums, the recommendations within building regulations and risk assessments should be followed.
- Remember that the unit in its entirety must be a qualified fire-rated system, and that the system profile is the correct size and specification for the building. Naturally, manufacturers are on-hand to support customers through the specification and installation process. Cutting corners, or simply not understanding the range of glazing systems available in today’s market, risks compromising the entire building and can lead to potentially fatal consequences.
Case Study:
Bedford Magistrates’ Court House
Fire-rated glazing was specified and installed in the Grade II listed Magistrates’ Court building in Bedford, as part of a £1.2 million refurbishment programme. The gothic building, constructed in the 1800s, now has fire-resistant glazing in doors, screens and windows, offering both fire integrity and insulation, as well as enhancing the building’s appearance.
As a public building used by hundreds of people every week, it was essential that the highest level of fire protection was installed. A specialist fire-resistant glazing system, which turns opaque when in contact with fire, was used. Such glass provides protection against heat, flames and hot gases for up to 180 minutes, which allows for enough time to evacuate the building.
Product Innovation
As our understanding increases of how glass behaves in fires, and modern glazing technology advances, so too does the appreciation of fire-rated glass’ benefits among contractors and installers. As a result, retrofitting such solutions in heritage buildings continues to become more popular.
Product innovation, driven by ongoing commitment to research and development programmes, will help to further enhance the performance of fire-resistant glass to the benefit of the entire glazing market. Not only will this allow for even greater levels of protection for people and property, but for more challenging refurbishment projects to be successfully completed in the future.
For further information, go to www.pilkington.com
