K15 is a rigid insulation board for use behind rainscreen façades and is one of the most thermally-efficient insulation products commonly used. As with many other types of insulation, it plays an important role in helping buildings to reduce their carbon emissions, retain heat and reduce energy costs. Kingspan has full confidence that cladding systems incorporating K15 can be safely used when supported by a successful BS 8414 test and installed correctly. K15 may be used in certain buildings in the UK today in accordance with the building regulations. It continues to be used in many types of buildings in many other countries.
Inclusion of insulation in cladding refurbishments (such as Grenfell Tower) is effectively a regulatory requirement.
To be deemed safe, a building’s cladding system needs to be compliant with the Building Regulations.
At the time of the Grenfell Tower refurbishment there were 3 ways in which cladding systems incorporating K15 could have been compliant: by the system passing a large-scale BS 8414 test; by a Desk Top Study; or by the provision of a fire engineering assessment. We are not aware of any cladding system containing the PE ACM used as the external rainscreen on Grenfell Tower having passed a BS 8414 large-scale system test with either combustible or non-combustible insulation. Simply put, cladding systems incorporating the PE ACM cladding used on Grenfell Tower were not safe for use with any form of insulation.
Importantly, there is no evidence that those involved in the refurbishment of Grenfell Tower relied on any BS 8414 test evidence in order to assess the suitability of K15 for Grenfell Tower. Had they done so, any competent consideration of the Building Regulations would have led to the conclusion that no form of insulation could be used with PE ACM.
K15 may still be used in a wide range of systems if they are compliant with Building Regulations. One of the routes to compliance is large-scale (BS 8414) fire testing. BS 8414 tests are not a test of insulation, but a test of a cladding system in which the insulation is used. As insulation is just one element of a large-scale system the same insulation can be part of different systems that fail or pass i.e. it is a test of system compliance, not product compliance.
K15 Testing Overview:
• There is presently a suite of successful large-scale BS 8414 tests of cladding systems, commissioned by Kingspan, which incorporate K15. They evidence the fact that multiple different cladding systems incorporating K15 can pass the test. This is critical information to help inform appropriate fire engineering judgements by suitably qualified building professionals.
• To our knowledge, there are also other successful large-scale BS 8414 tests of systems incorporating K15 which were not commissioned by Kingspan Insulation.
• As far as Kingspan Insulation is aware, no other rainscreen insulation has been used in so many different cladding systems that have successfully passed BS 8414 tests.
• In January 2022, the BSI published PAS 9980, a new code of practice sponsored by the UK government for appraising the fire risk of external wall construction and cladding on existing blocks of flats. PAS 9980 allows for retention of K15 in appropriate circumstances, in cladding systems which are supported by BS 8414 test evidence and installed correctly, subject to an appropriate fire engineering judgement.