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Last edited 28 Sep 2020
ACM cladding testing by BRE
The Government acted to support owners and residents of high-rise buildings to ensure fire safety in the light of the Grenfell Tower fire. Landlords engaged in a checking and testing process for Aluminium Composite Material (ACM) cladding.
The initial tests conducted at BRE on behalf of the Department for Communities and Local Government (DCLG) were a screening test to identify which ACM panels were of concern. They test the filler in the core of the panel to check if it is of limited combustibility (category 1) or not (category 2 or 3).
The filler is one element of the overall cladding system. If the panel core fails the test, landlords are expected to take the recommended interim fire safety measures issued by government on 22 June 2017.
The equipment and procedures used in the screening tests were based on the BS EN ISO 1716:2010 test standard. As the purpose of this testing was to quickly and reliably screen the core material within the panel, the full procedures set out in that standard were not followed as they were unnecessary to determine which type of panel had been submitted for the screening test. These screening tests should not be confused with a formal classification test against the standard.
You can read further information and detail on the testing process on the gov.uk website.
An independent expert panel was set up to advise the government on other urgent steps that should be taken to improve fire safety. BRE's Chief Executive, Dr Peter Bonfield sits on that panel. They will issue advice imminently to clarify further steps landlords could take to inform their decisions on the cladding systems they have in place, and on checking insulation and other components of typical wall construction.
On 6 July 2017, the Grenfell Tower independent expert advisory panel advised that further testing should be carried out by BRE to establish how different types of ACM cladding behave in a fire in combination with different types of insulation. This, they suggest would help landlords decide what further measures may be needed to make their buildings safe.
The tests will look at 6 combinations of 3 different types of ACM cladding, with polyethylene, fire retardant polyethylene, and non-combustible mineral cores, combined with insulation of rigid polyisocyanurate foam and non-combustible mineral wool. The tests will be carried out in accordance with BS 8414, and involve building complete cladding systems 9 metres tall and then subjecting them to a severe fire. The results will be made publicly available, but landlords should take professional advice on the implications for their buildings.
 Test 1
The first results of these tests were revealed on 28 July 2017, when DCMS announced that a system comprising ACM cladding with polyethylene filler (Category 3) and foam insulation, with fire breaks and cavity barriers in place did not satisfy the requirements of the building regulations. 82 buildings are thought to have this combination of materials in their wall construction.
 Test 2
On 2 August 2017, the government announced that the second series of tests had been completed, testing a system consisting of ACM cladding with a polyethylene filler (category 3) with stone wool insulation. The Grenfell Tower independent expert advisory panel advised that the combination does not meet current building regulation guidance. There are 111 buildings known to use this system.
 Test 3
On 8 August, results of the third series of tests was published, consisting of ACM cladding with a fire retardant polyethylene filler (category 2 in screening tests) with PIR foam insulation. Again, the Grenfell Tower independent expert advisory panel advised that the combination of materials does not meet current Building Regulations guidance. The government reported that there are 13 buildings over 18 m tall in England known to this combination. It was also reported that to further build the evidence available, the government has commissioned a seventh large scale test on ACM cladding with fire retardant polyethylene filler (category 2 in screening tests) with phenolic foam insulation.
 Test 4
On 11 August, the results of the fourth round of tests was published, relating to ACM cladding with a fire resistant polyethylene filler (category 2 in screening tests) and stone wool insulation (a form of mineral wool). 13 buildings over 18 metres tall in England are known to have this system of cladding. The combination of materials passed the test and so can be compliant with the Building Regulations when installed and maintained properly. This means it could offer a possible solution for buildings with cladding systems that have failed tests. However, building owners need to take professional advice to ensure the safety of their building. Following the tests, Advice for building owners: large-scale wall system test 4 was published by the Grenfell Tower independent expert advisory panel.
 Test 5
On 14 August, the results of the fifth test, assessing ACM cladding with a limited combustibility filler (category 1 in screening tests) with PIR foam insulation were published. The Grenfell Tower independent expert advisory panel reported that these results show the combination of materials can comply with the building regulations. The government is not aware of any buildings over 18 metres in England using this combination of materials, but it could offer a solution for buildings which have been identified as a fire hazard through previous large-scale tests.
 Test 6
On 21 August, the results of the sixth large scale tests were published, revealing that a system consisting of ACM cladding with a fire retardant polyethylene filler (category 2 in screening tests) with phenolic foam insulation did not satisfy the Building Regulations. It is thought that there are 22 buildings over 18 metres tall in England with this combination. Appropriate safety measures have been put in place for all 22 of these buildings. Results of the final large-scale test (ACM with a limited combustibility filler with mineral wool insulation) – and consolidated advice to landlords based on all the 7 tests – will be published shortly.
 Test 7
On 25 August, the results of the final test were published, a system consisting of ACM cladding with a limited combustibility filler (category 1 in screening tests) with stone wool insulation. The Grenfell Tower independent expert advisory panel reported that this combination of materials can be compliant with the building regulations when installed and maintained properly. The government is not aware of any buildings over 18 metres in England using this combination, however, it could offer a possible solution for buildings with other cladding systems which have been identified as a fire hazard through previous large-scale tests. The government will shortly publish consolidated advice to landlords based on all the 7 tests.
In a statement to Parliament on 5 September 2017, Communities Secretary Sajid Javid confirmed that the cladding systems that passed the tests are in use on eight social housing towers. Systems that failed are in use on 165. He also stated that inspections have highlighted other safety issues related concrete panel systems.
In February 2018, BRE issued a statement revealing that the original tests they had carried out on the cladding system in 2014 were carried out on a test system that was not constructed according to Celotex’s design specification. The statement said; "The cladding system in that test included Celotex RS5000 and fibre cement board rainscreen (declared reaction to fire classification A2) – this was not an Aluminium Composite Material (ACM), nor was it the cladding system on Grenfell Tower." BRE made clear that they did not design, select or install the test system, and were not involved in the sample selection process.
 ABI tests
On 25 April 2018, the Association of British Insurers (ABI) described the full-scale tests used to demonstrate that cladding systems meet fire regulations as “utterly inadequate” suggesting that they underestimate the ferocity and spread of real fires.
ABI commissioned a series of experiments by the Fire Protection Association which demonstrated that the tests do not represent real-world conditions. For example, if builders have left gaps in cladding or installed vents, and an apartment contains plastics and furniture, the building will be significantly more flammable. ABI has called for a ban on the use of all combustible materials in external cladding systems.
 Related articles on Designing Buildings Wiki
- BRE articles on Designing Buildings Wiki.
- ACM cladding.
- Approved Document B.
- BS 8414 Fire performance of external cladding systems.
- BS 9999: Code of practice for fire safety in the design, management and use of buildings.
- BS 9991:2015 Fire safety in the design, management and use of residential buildings. Code of practice.
- Celotex RS5000 PIR insulation.
- Cladding for buildings.
- Grenfell Tower articles.
- Grenfell Tower fire.
- Grenfell Tower independent expert advisory panel.
- HPL cladding.
- Independent review of the building regulations and fire safety.
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