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RCI January 2018

RCIMAG.COM JANUARY 2018 041 Passing the test Last month, the interim report from the Hackitt Review confirmed what many in the industry had said for some time: that the current regulatory system is unclear and “unfit for purpose”. As work continues to create a better system, the Government’s priority has been to address high rise buildings considered at risk. In August, the Department for Communities and Local Government (DCLG) undertook testing which was meant to provide clarity on which cladding configurations could be deemed compliant. The limited scope of this programme, however, may have led to systems being incorrectly classified as non-compliant. Since then, further large-scale, full system tests have been carried out showing that a number of additional constructions can achieve a pass. These tests, currently in the process of being signed off by the BRE, may mean that remedial work is unnecessary for some buildings or provide simpler recladding options in cases where it is. Current Testing The DCLG carried out fire safety testing on seven cladding configurations. The testing was conducted using the full system, large-scale test – BS 8414 – in accordance with BR 135: ‘Fire performance of external thermal insulation for walls of multi-storey buildings’, which provides clear pass / fail criteria for the assessment of façade systems when tested to BS8414. As I discussed in the November issue of RCI, the purpose of the BS8414 test is to replicate a fire which begins inside a room, breaks out through a window and exposes the external building façade to fire. To achieve this, the complete façade system is erected on a test wall to a height of at least 8 metres. A large combustion chamber at the base of the wall is then lit and allowed to burn for 30 minutes. Temperatures are monitored from a range of positions on the wall throughout the 60 minute duration of the test. To pass, flames must not reach the top of the wall at any point and temperature limits must not be exceeded. Limitations Crucially, this test is only designed to assess the performance of the specific cladding configuration used. In practice, very minor adjustments to a system’s design, such as the width of the cavity, can have a significant bearing on its performance in testing. For this reason, it is deeply concerning that DCLG have used the results of tests on seven individual configurations to categorise the performance of a whole range of systems. For example, all solid core, Euroclass A2, Aluminium Composite Material (ACM) cladding panels have been deemed compliant for use with all mineral fibre and PIR insulation on the basis of two tests. This reductive approach ignores significant variations between manufacturers in the composition of both ACMs and insulation products which fall within these categories. In addition, all seven tests used a 20mm gap between the ACM panels within the cladding system. In the UK, this is a fairly uncommon arrangement and 4-10mm gaps would be much more the norm. This wider gap will allow a greater air-flow into the system to the detriment of system performance. This could potentially lead to the unnecessary replacement of cladding systems which are, in fact, perfectly compliant with Building Regulations. Performance Gap For example, the DCLG tests assessed stone wool, phenolic and PIR insulation materials in three separate systems with the following configuration: • FR cored ACM cladding with a 20mm gap between the panels. The systems using PIR and Phenolic insulation were shown to narrowly fail these tests, suggesting any existing constructions with these material combinations might need to be replaced. Over the past few weeks, however, new BS8414 testing has shown that: • Kingspan Kooltherm K15 phenolic insulation easily achieves a pass on a masonry wall, with Alpolic FR cored ACM cladding and a gap of 10mm or 4mm between the cladding panels. In addition, Kingspan Kooltherm K15 phenolic insulation has also passed BS8414 tests in systems with the following components: • Solid core, Euroclass A2, Alpolic ACM cassettes on a masonry wall • Solid core, Euroclass A2, Alpolic ACM flat panels on SFS and masonry walls with 20 mm gaps between the cladding panels Solutions Therefore, if you have phenolic insulation with an FR cored ACM, but the joints between the ACM panels are 10mm and not 20mm, then the “fail” label and the need for remedial works may be invalid. Similarly, if you are looking for a solution to replace a PE cored ACM installed over Kingspan Kooltherm K15 phenolic insulation, it might be as simple as replacing the PE cored ACMs with Alpolic FR cored ACMs with a gap (between ACM panels) size of 10mm or less. This could provide an acceptable alternative solution to heavier options, helping to address potential structural limitations. The BRE holds a register of all cladding configurations which have also been successfully tested to BS8414 testing at: www.bre.co.uk/regulatory-testing. Note that recent tests will not yet be listed. In the meantime, please contact Kingspan Insulation for further information and full details of the successfully tested systems. www.kingspaninsulation.co.uk Adrian Pargeter, head of Technical and Product Development at Kingspan Insulation discusses the limitations of the large-scale fire safety tests in the wake of Grenfell INSULATION


RCI January 2018
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