A cracking question

A cracking question

A report produced in November 2016 by a group of fire resistant glazing experts looks at the current state of play in the way glass is used in fire-sensitive areas of buildings and questions whether the current regulations are fit for purpose.

A major trend in building design over the past 100 years has been the emergence of glass as one of the most commonly used building materials. In order to preserve building safety and the safety of those who use them, it is essential that glazing design and installation technology reflects the increased use of glass as a  functional construction component.

Technological developments have transformed the ability of glazing to withstand fire for extended periods of time, as well as delivering larger pane sizes and clarity along with  enhanced protection. However, these advances have created new challenges in terms of guaranteeing the quality of fire-resistant glazing across the market, and ensuring the right products are always used in the appropriate settings.

The Pilkington Fire White Paper looks at the way glass is used in fire-sensitive areas of buildings, and the issues which need  to be addressed and also asks whether we could  do more to ensure glazing delivers the right level of protection against fire.

In his Foreword Steve Bond, Customer and Technical Support Manager, Fire Protection, Pilkington UK thanked the contributors to the report adding “ I hope you find this a useful snapshot of a developing part of the glazing market playing an essential role in the built environment around the world”.

Avert disaster – avoid disruption

Ensuring a building’s occupants and contents are protected from the risk of fire begins on the drawing board, and consideration and mitigation of hazards must be baked into the design process from the word go, writes of Tim Kempster, Managing Director, Wrightstyle.

To properly address the risks all possible hazards facing a building’s occupants, structure, resources and continuity of operations should be considered and only then can a design team make  well-informed decisions on acceptable  risk levels
and cost-effectiveness.

Compliance with fire regulations, while important and necessary, is not sufficient in Tim’s view. They deal only with protecting human safety and, while this is clearly by far the most important concern, it is not the only one. Even in the  best-case scenario, any fire will be disruptive. Often it can shut down a business, perhaps permanently, or destroy information vital to continued operations.

It is crucial to ask business continuity questions like ‘if fire does happen, can we quickly move manufacturing elsewhere?’ and ‘if we lose data on-site, is all that business-critical information also held elsewhere?’.

Modern glazing systems can play a central role in the resulting mitigation strategy by providing complete protection against convection, conduction and radiation – the three means by which fire spreads through a building. It can be used as curtain walling, internal doors, floors or fire screens, creating a barrier for up to three hours, giving more than enough time for a safe evacuation and for emergency services to contain the blaze effectively, minimising losses.

However, the designated responsible person for a project must also ensure that the fire glass and its framing systems have proven compatibility. That means insisting on comprehensive fire test certification that covers both elements because, in a fire, the glass and its frame have to function together to prevent the spread of fire, smoke or toxic gases. If one fails, both fail, with potentially catastrophic consequences.

Regulation & guidance

In its contribution to the report, The Glass and Glazing Federation (GGF) considers whether regulation and guidance is fit for purpose. In the UK the guidance in Approved Document B  (AD B) has been successful in establishing a  firm foundation for fire safety design using  fire-resisting constructions, and it is important that any changes stay true to the core principles of fire separation and compartmentation.

Steve Rice, Director of Technical Affairs for the GGF stresses that there needs to be greater attention to the wider risks fire presents in modern buildings, both to property and people. That particularly concerns glass. AD B is rooted in history, but modern building design, technologies and practices have moved on. We now have bigger and more complex buildings, using more glass in larger assemblies. Risk-based decisions  – where the approach is based on the probability of any given event occurring, rather than an attempt to achieve absolute protection – are now commonplace.

While this is a practical necessity, it tends to shave levels of confidence off safety margins. Given that budgets often dominate decision making on projects, it does not necessarily lead to the best outcomes in terms of assured fire protection.

But better property protection and higher levels of assured protection for individuals in more complex modern buildings requires more and better protection from glazing systems – in particular, a greater use of insulation together with integrity, also with longer protection times.

Integrity and insulation fire-resisting glass types have been developed to suit a wide range of applications and have achieved proven performance based on extensive testing. The guidance should better recognise these advances.

Moving with the times

The developments in technology have been significant across the board and there is now more product choice and more levels  of performance to exploit.

This is particularly illustrated by high-performing clear and laminated integrity glass products, such as modified toughened glass and laminated types that also provide a good level of fire-resistance insulation. For example, it is now possible to specify these products with 30 minutes’ integrity and 15 minutes’ insulation.

Regulations need to keep in touch with what they regulate and, despite its success, AD B  is lagging behind. A makeover is required. But, in the name of fire safety, it must maintain what is good and build on it to better reflect modern practices and technologies.

The basic fire-resistance levels called for in glass positioned in different areas within a building are laid out in the Building Regulations. However, detailed guidance is contained in another Government publication – Approved Document B (AD B).

The purpose of these minimum requirements is to ensure that fire is contained within the room or space of origin, and that the spread of smoke and flames is inhibited by compartmentation. This will ensure that occupants, and the emergency services, have time to evacuate safely.

The partitions separating compartments or rooms must achieve specific periods of fire-resistance, and so the fire-resistance performance of any glazing in such walls is crucial.

Fire-resistant glazing will only perform as  intended when it is correctly installed with appropriate glazing materials in a suitable  fire-resistant frame.

Today modern architecture favours transparency even far beyond the facade: the architects prefer natural light and
open spaces to determine the design of large buildings right down to their structural core. Wherever these “open” concepts meet local construction and fire safety requirements for the protection of human life and property, transparent fire-resistant glazing comes into play. This allows modern, bright and open space design, as well as safety to be combined in a variety of multi-functional systems.

The full report Pilkington Fire White Paper can be read here https://www.pilkington.com/en-gb/uk/products/product-categories/fire-protection