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Wednesday23 August 2017

Grenfell cladding 'is banned in the UK', says chancellor

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Philip Hammond says his ‘understanding’ is that material should not have clad tower - and will be focus of criminal probe

The use of the type of cladding used to cover the Grenfell Tower in Kensington is banned in the UK, according to the chancellor, Philip Hammond.

Speaking on yesterday’s Andrew Marr programme on the BBC, Hammond was asked if the government would pick up the tab for replacing such material currently cladding tower blocks across the UK, if it were found to have been used.

Hammond ducked the question, instead saying he believed the material was banned here.

“My understanding is that this material, which is banned in Europe and banned in the US, is also banned here.

“There are two questions around this. Are our regulations correct? Do they permit the right kind of materials and ban the wrong sort of materials?

“And secondly, were they correctly complied with? Obviously that will be a subject the [public] inquiry will look at. It will also be a subject the criminal investigation will be looking at.”

The prime minister Theresa May faces mounting criticism over the government’s response to the disaster, which has so far known to have claimed nearly 60 lives. The local Conservative-led council has also been taken to task for not providing enough support for surviving victims of last week’s blaze and has now had its responsibilities taken over by central government’s Gold Command.

Thomas Lane, editor of Building Design, writes:

Reynobond is not banned in the UK. It has a BBA certificate which includes details of the panel’s compliance with European and British fire standards and Arconic, the manufacturer of Reynobond publish the fire ratings in its technical guidance.

Reynobond PE, the panel which features a polyethylene core has been tested according to the standards set out in BS EN 13501-1: Fire classification of construction products and building elements. According to the certificate the panels have a Class 0 rating for the surface spread of flame which is the highest rating. The certificate also says the polyethylene cored panel has a reaction to fire classification of B –s2 and the fire retardant version a rating of B –s1. This contradicts Reynobond’s fire certification documentation which states the fire retardant version of the panel has an A2 rating. The highest ‘A’ rating requires materials to be non-combustible and an ‘F’ rated material is easily flammable. The polyethylene cored Reynobond panel is regarded by BS EN 13501-1 as being combustible with very limited contribution to fire.

According to Part B, the building regulation which deals with fire safety, the external envelope of a building should not provide a medium for fire spread if it is likely to be a risk to health and safety. Any insulation product or filler material used in the external wall construction of a building over 18m tall should be of limited combustibility. A table in Part B, diagram 40 shows what classification of material can be used in different parts of a building. It states that materials with a classification of class C-s3 – combustible with a limited contribution to fire - can be used in buildings up to 18m tall. A building over 18m tall must use materials with a classification of B-s3 or better. This suggests both types of Reynobond panel would meet the requirements of Part B for the flammability of external cladding.

There appears to be a contradiction in Part B. Table A7 in the appendix defines materials of limited combustibility which must be used on buildings over 18m tall. This states a material tested to BS EN 13501-1 must have a rating of A2 – s3 or better, in other words non-combustible. According to the BBA certificate neither of Reynobond’s panels would meeet this requirement. Arconic’s own documentation states that the fire retardant version would have been compliant with this requirement but not the polyethylene cored panel.

 

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Readers' comments (15)

  • The problem may be that the wording of the part of the regulations in Approved Document B ( AD B ) is ambiguous.

    https://www.gov.uk/government/uploads/system/uploads/attachment_data/file/441669/BR_PDF_AD_B2_2013.pdf

    "12.7 In a building with a storey 18m or more above ground level any insulation product, filler material (not including gaskets, sealants and similar) etc. used in the external wall construction should be of limited combustibility (see Appendix A). This restriction does not apply to masonry cavity wall construction which complies with Diagram 34 in Section 9."

    Rainscreen cladding isn't insulation, it has a weather shielding and aesthetic function. The etc. at the end does provide some doubt as to what exactly is meant. However if you look at this BRE press release for the 2nd edition of the fire safety document referenced in 12.5

    "BR 135 Fire performance of external thermal insulation for walls of multistorey buildings"

    http://www.redbooklive.com/filelibrary/Articles/The_dangers_of_external_cladding_fires_in_multi-storey_buildings_~_RCI.pdf

    By their understanding, cladding seems to be meant to be included in 'etc.' in 12.7

    "any product used in the external wall construction (except for gaskets, sealants and similar components) in buildings with a storey 18m or more above the ground, must be of limited combustibility"

    Taken that as read, that would mean that the materials would have to meet limited combustibility as in Appendix A on page 130 - i.e. European class A2-s3, d2 or better in European standard in accordance with BS EN 13501 - 1:2007 Fire classification of construction products and building elements, Part 1 - Classification using data from reaction to fire tests

    Neither older Reynobond product, PE or the more fire retardant FR meet those tests, only meeting class B - s2, d0 and B - s1, d0 . Presumably that is why Arconic have now developed the Reynobond A2 that does meet it, referenced in their new 'fire solutions' document (dated Dec 2016, Jan 2017 in filename). The question is what if any advice did Arconic (then Alcoa) offer to distributors at the time of the Grenfell refurbishment? I have looked through all the documents on their old website and have found not one warning about building height

    https://web.archive.org/web/20150905203951/http://www.alcoa.com/aap/europe/en/info_page/down_brochures.asp

    So sadly it seems we are facing incompetence all round, with dodgy wording in the regulations, and the manufacturers being less than forthcoming about the safety risks of their products.

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  • Philip Hammond shouldn't be surprised the Reynobond PE cladding is Class 0 certified under British regs, by the manufacturer (even though they also classify it as combustible under French regs). After all, he is one of the co-creators of our great, deregulated austerity utopia.

    Reynobond, the manufacturers, do clearly state that they offer three ACM cladding products, two with european fire ratings (A2 & B) and one without;

    PE - combustible - for buildings up to 10m high
    FR - fire resistant - for buildings up to 30m high
    A2 - non-combustible - for buildings above 30m high

    They also say the designers choice is crucial, as fire can spread to the whole building extremely rapidly.

    It would seem inconsistent to regularly update Part L, encouraging overcladding for heat loss, but not to review Part B since the Tories took office. Unless you're concerned a review might require costly sprinkler systems to be installed in thousands of older tower blocks.
    Especially in towers like Grenfell and its immediate neighbours, with only one means of escape and no fire alarm for the building as a whole, only individual smoke alarms.

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  • Marc, please have a look at my comments. Arconic have only recently produced this A2 90% mineral core Reynobond, and the fire guidance relating to it and the others regarding high buildings was only released this year.

    Regarding the Class 0 rating, if you take the BRE's understanding of 12.7 to include cladding, individual components have to be European class A2-s3, d2 rated, neither of which older Reynobond product fulfils that

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  • Ladro, many excellent points thank you.

    Indeed, the earlier literature only offered two choices the PE and FR, described as plastic or mineral core construction, both European class EN... B s2 d0, B s1 d0 respectively.

    Neither are suitable for a tower but erring on the side of caution (for a modest cost increase) by using the higher rated, low smoke material would certainly have saved lives.

    I'm no envelope specialist and I'm sure there will be much discussion of how the regs apply, but am I mistaken in thinking BR_PDF_AD_B1_2013 Sec 8.4 is the decider for a dwelling? Therefore Class 0?

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  • Hi Marc. I think Volume 1 of AD B only applies to detached/semi detached homes, not blocks of flats. If you look at page 6, it also says:

    "0.1 Where very large (over 18m in height) or unusual dwellinghouses are proposed, some of the guidance in Volume 2 may be needed to supplement that given by Volume 1."

    It appears the architects for Grenfell originally were going to go with Proteus cladding which has a honeycomb metallic core, which is 10-20% more expensive than plastic cladding:

    http://www.dailymail.co.uk/news/article-4612626/Fire-safe-panels-initially-chosen-Grenfell-Tower.html

    I assume it was probably this one, the Proteus HR

    https://www.proteusfacades.com/products/proteus-hr/

    If you look at the datasheet for that linked at the bottom, you'll see, on page 10, it states that it meets Class 0 rating for BS 476 Parts 6 (fire propagation) and 7 (surface spread of flame), which is better than both Reynobond products. It also states there is a non standard A2 version available that was used on the London Underground. It appears, on one interpretation of AD B Vol. 2 that only that may only be actually suitable for buildings over 18m.

    KME Architectural Solutions lost out to Omnis Exteriors, who were presumably the (or a?), distributor for Alcoa, now Arconis products in the UK. How much did Omnis know about the fire risks associated with both Reynobond products for tall buildings? If they only had what was on the old Alcoa site, not much it would seem.

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  • Should also add that, I don't think the insulation used, or other factors such as cavity barriers be overlooked. The insulation used was Celotex RS5000

    https://www.celotex.co.uk/products/rs5000

    Despite saying on the first page of its datasheet it has Class 0 performance for BS 476, on the second page it only has a Pass for BS476 Parts 6 (fire propagation) and Class 1 for 7 (surface spread of flame), so confusing to say the least?

    It also states it has passed BS8414-2 and meets the performance criteria of BR135 which as I understand it is a separate test designed by the BRE specifically to test external cladding / insulation systems. Whether that means it passes the European A2 - s3 , d2 or better test or national equivalent, I am none the wiser!

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  • Ah, OK, go it. The second page of the Celotex datasheet refers to a mock cladding system test, incorporating the RS5000, and the figures of Pass for 6, and Class 1 for 7 was for that system as a whole. However, it would seem somewhat misleading for them to state it has Class 0 rating on the more basic BS 476 standard, without making its actual performance in a system is significantly lower, although still a pass.

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  • The combinatorial effects of coatings, claddings and insulation from different manufacturers in constantly varying combInations across the UK suggests that fire research and warranty companies should play a bigger role. The heavily charred purported PIR insulation at Grenfell shows how much combustion takes places with materials, which by themselves do not support indefinite combustion in isolation, but will contribute to adjacent sources in some situations, in the same way that a candle is designed. The final combined installation and site location is 'the thing', not individual components and individual ratings?

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  • I believe Omnis have a great deal of knowledge and experience of cladding systems - however their main focus is in the provision of complete (tested and certified, assuming to BR135, as a complete system) fascade solutions. The difference in this case is Omni was only asked to supply the ACM PE rainscreen cladding, and the complete system was designed by either the architects, or the installer.

    It seems a bespoke solution was built without appearing to realise that some of the components they were selecting were only certfied for their intended use when used as part of a complete, tested and certified system.

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  • Thanks for that info Steve. I have found a very good presentation given in Abu Dhabi in 2012 below, by Dr Sarah Colwell, principal consultant to BRE (Building Research Establishment, former quango privatised)

    http://www.sesam-uae.com/safetyauh/presentations/Sarah.pdf

    She shows the testing facility at BRE and explains the testing procedure (pg.19-35)

    BS 8414-1:2002 being cladding systems on masonry structures, BS 8414-2:2005 on a lightweight steel frame

    The test facility at BRE for BS 8414 has been there since 2004

    http://www.bre.co.uk/news/Fire-testing-external-cladding-206.html


    She then gives a summary, on page 39, of the UK regulations for buildings above 18 metres, which clears some confusion up for us:

    - External Surfaces should conform to diagram 40 - which means the rainscreen cladding must meet class 0 (national class) or Class B-s3, d2 or better (European class)

    - All insulation and filler materials should be A2-s3, d2 or better (EN13501-1)

    OR

    - Test the complete system to BS 8414 and classify in accordance with BR135

    And

    - All cavity barriers and fire stopping guidance needs to be followed


    So Reynobond PE meets Class 0 for BS 476: Part 6 (fire propagation) and meets Class 1 for BS 476: Part 7 (surface spread of flame). It also meets the European Class B-s2, d0 (s being smoke, d droplets, lower number better). So it's use was according to current regulations. Class 1 of Part 7 is overridden by Class 0 of Part 6, as explained by a Probyn Miers journal article last December:

    http://www.probyn-miers.com/perspective/2016/02/fire-risks-from-external-cladding-panels-perspective-from-the-uk/


    "Class 0 is not a classification identified in any BS test. Class 0 is achieved if a material or the surface of a composite product is either:

    composed throughout of materials of ‘limited combustibility’, when tested to BS 476-11 or classified as Class A2-s3, d2 in accordance with EN 13501-1; or

    a Class 1 material which has a fire propagation index (I) of not more than 12 and sub-index (i1) of not more than 6 when tested to BS 476-6: I is overall performance and i1 is performance after 3 minutes."

    I recommend reading both the Probyn Miers article and Sarah Colwell's presentation wholeway through. It does appear the current regulations are not sufficient to protect high rise occupants from fire, and the concept of Approved Documents of the Building Regulations apparently only being informative advice rather than legal mandatory requirements (stated under 'Revisions to UAE Fire Code regarding Exterior Cladding') seems another flaw in protections for the public.

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