A view of gaining an exemption for laminated safety glass in balcony balustrades
Steve Bond, customer support manager for fire protection at Pilkington UK, explains how the glass and glazing industry is undertaking research into the performance of laminated safety glass when subjected to fire to help the government consider an exemption for the use of laminated safety glass in balustrades on high-risk high-rise balconies.
Architects like glass balustrades. They’ve been used for decades on balconies to help give buildings a contemporary edge, while providing uninterrupted views and a level of wind proofing for occupants.
Access to an outdoor space has also become increasingly more desirable during the current Covid epidemic.
But after the necessary shake up of fire safety building regulations in 2018 – which included the need for attachments on the external facade to be classified as reaction to fire class A1 or A2 – the use of laminated glass balustrades on balconies, which are typically two panes of 8mm, 10mm or 12mm thick glass with a polymer interlayer, was effectively banned.
This cuts a major supply opportunity for the glazing sector. One that looks set to rise as developers build upwards to meet the UK’s housing needs.
Meanwhile, it narrows the choice for technical designers to alternatives like steel railings, which occupants, in the search for privacy and wind reduction, can unwittingly dress in highly flammable shading and accessories, if not properly policed by a building’s fire safety manager.
In response, the industry is working with the government to review a possible exemption of glass balustrades from the ban on the use of combustible materials, in line with recommendations from key bodies including the Royal Institute of British Architects (Riba).
Central to gaining an exception on the ban is testing and evidence.
There is currently no strong evidence that laminated safety glass contributes to the propagation of flames on balconies. Examinations of recent blazes also show glass balustrades being intact after exposure to flames.
Still, conventional laminated safety glass is classified B when tested to the requirements of EN13501-1, sitting below the required A1 and A2 ratings to specify materials for use on the exterior of a building.
However, there is hope for an exception despite this rating. Laminated safety glass has already gained exception for exterior use for doors and windows under Regulation 7, which provides guidance on the use of materials in buildings.
But to grant any further exceptions, the Ministry for Housing, Communities and Local Government (MHCLG) will need thorough evidence that balustrades incorporating laminated safety glass do not propagate or aid the spread of flames in the event of a fire.
Encouragingly, policymakers are keen to hear the industry’s concerns and evidence, launching the review process with a technical consultation paper in January 2020.
The Glass and Glazing Federation (GGF) is now working closely with the MHCLG’s research group reviewing the ban of combustible materials.
But it isn’t just our sector advocating for change. The wider balcony industry and laminated safety glass processors also have interests in overturning the effective ban on laminated safety glass.
We’ve been working with some of these companies and the GGF to secure the evidence that the MHCLG and their advisers need for their review.
So far, we’ve conducted more than £200,000 worth of testing at our German test facilities and the evidence we’ve collected is promising. The wealth of performance data collected gives a comprehensive view of various interlayer materials and glass/interlayer combinations which are commonly used in these applications.
We also commissioned our in-house refractory modelling team to undertake thermal modelling experiments. This enabled us to determine the temperature and incident heat flux impinging on a glass balustrade at differing heat flux intensities.
A single experiment can take days to run but results in exceptionally detailed heat flux and heat flow data.
All this data has been submitted to MHCLG and its commissioned research team for consideration.
Conducting the testing and producing evidence is an ongoing process.
But it may be some time yet until we know whether an exemption is likely to be granted. The pandemic has understandably diverted government resources in the last year, but we’re seeing momentum beginning to build again.
As fire safety is of critical importance, the industry would not advocate the use of laminated glass in balustrades if it is believed that it could contribute to fire spread.
With the right collaboration between industry, trade associations and policymakers, we can restore confidence in the building product supply chain and create a safer built environment.