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  1. Andrew, thanks again for these incredibly thorough analyses. The section 13 of AD B Vol 2, somewhat threw me with its inclusion of limited combustibility as a path to a Class 0 rating, when I had understood it to be a pass of BS 476 Parts 6 (fire propagation) and Part 7 (surface spread of flame) as explained in most sources. And, as you say, it is slightly unclear, in reference to both ‘a material’ AND ‘the surface of a composite product’. Does it mean that the limited combustibility requirement applies only to the singular ‘material’ and the surface flame tests to the surface of composite products? Or is it that anything of limited combustibility would de facto pass both surface tests BS 476 Parts 6 and 7?

    Whatever it is, it seems the resultant implication is that, to reach, as is stated, ‘the highest National product performance classification’, ‘Class 0’, you only need to pass surface flame tests, and NOT reach the, in reality, higher safety standard of limited combustibility. It almost seems like someone lobbied way back when this Class 0 highest UK rating was made, against limited combustibility being the sole way of achieving this highest rating, and insisted on the surface tests being an alternative means of reaching it. Do we know when Class 0 was first defined? Of course, the reality of this loophole greatly favours the manufacturers of the plastics PIR/PUR/phenolic insulation with its aluminium foil coating, and the composite cladding panels with their thin metal outer layers.

    Good analysis of the BBA Agréments for Kooltherm, although patently false statements were made, they seem to have been corrected, but as you say, if people had understood them to be accurate at the time, installations may have occurred which were not in compliance with AD B Vol 2.

    Regarding the ‘advisory’ statements made by the Building Control Alliance (GN 18/June 2014) in relation to the regulations (and subsequent ones by the National House Building Council), it is hard to believe for me that these were NOT made with the tacit or overt permission i.e. this was discussed in face to face meetings, of senior government and civil service officials. But as you say, the reality of this is chaos, where some architects and cladding designers (however much you might argue that they should be paying attention) still refer back to the Approved Document B, and are unaware or, at least, perhaps only partly aware, having been informed by word of mouth from others, of these new proclamations. One example of this chinese whisper effect, may be the requirement that is clear, in the BCA GN 18, that:’the client may instead submit a desktop study report from a suitable independent UKAS accredited testing body’

    However if you look at this article in construction manager magazine, which uses the Portsmouth student accomodation featured on Newsnight as a case study:

    He states:

    “The report must be backed with the results of testing by a suitable UKAS accredited testing body, and should make specific reference to any actual tests that have been carried out on the product. In addition to fire test data, the specialist will also typically require further information including plans, elevations, section and fire barrier details. Note that the specialist does not have to be UKAS accredited.”

    So the GN 18 says the desktop study must be from a UKAS accredited testing body i.e. BRE or Exova (the merger of Warrington & Chiltern Fire), but now we have this industry figure saying the desktop study doesn’t have to be from them, just use some of their data- and would that be actual BS 8414 tests, or desktop studies? And then we have the further pronouncement from the NHBC in 2016, which stated that, as many Class 0/Euro Class B products have passed BS 8414 tests, all products in a cladding system may be Class 0/Class B, directly contradicting the BCA\’s 2014 pronouncement.

    It seems that it is pretty clear, that industry cannot be trusted to make up or amend these rules, and government and the civil service must start to re-employ in house scientific expertise who can properly assess what is and what is not safe, without relying on industry, to frankly, bamboozle them in to making safety regulations that fit their own commercial preferences.

  2. Thanks for this, John. On the point of whether a desktop study should be conducted by a UKAS body, this was a requirement of the first edition of BCA TGN 18 (2014), but not of the second (2015) – see my footnote 3 above.


  3. Aha, thanks Andrew, missed that. So no doubt gave in to more industry lobbying, and is it clear whether the studies can be based on previous desktop studies as well as full BS 8414 tests? Because if the former, given the quality of some desktop studies that we know of by Exova, and god knows what by these ‘independent fire specialists’, it can basically descend to ‘my mate said it was OK’ and we are back to where we started – which almost seems to be what the NHBC wanted to codify by stating, just let all Class 0/Euro Class B products be used, until they quickly backtracked after Grenfell.

  4. The NHBC\’s 2016 document is really shocking ( But of course these developments in 2015-6 cannot be used directly to explain what happened at Grenfell Tower, where the decisions about cladding were made I think in mid to late 2014. But I think they may give an indication of the type of culture that was prevalent a year or two before, but which didn’t manifest itself, so to say, until a little later. Andrew

  5. I found an article previously (now can’t find link) that explained that desktop studies were proposed, because firms were simply not doing real BS 8414 tests, because of the expense, and presumably, by logical deduction, the implication was they were also often not meeting the AD B requirements of limited combustibility insulation. I’ve found a couple of interesting articles in Building Construction Design. In the first, from July 2015, Adrian Pargeter, Head of Technical and Product Development for Kingspan Insulation, describes the usage by industry of the BS 8414 system as ‘unrealistic’, presumably due to cost, and heavily promotes the desktop study and fire engineered approaches, describing the former as the ‘sensible route’, and the latter ‘a far better approach’.

    The second article from January, 2017 is by Danny Phelan, national sales manager at Panel Systems. Interestingly he cites the 2013 update of Approved Document B, and claims that it:

    “gives clear guidance on the acceptable use of combustible materials within the external cladding system”

    and “recommends either the use of materials of limited combustibility (or non combustibility in Scotland) for all key components”

    Unless the 2013 version is difference from the 2013 version that is online, it does NOT say that all key components should be of limited combustibility. But he then does cite the GN 18 of the BCA which was the first document that I know that actually proposed this.

    Very interestingly, he then states that “Questions have been raised by Building Control Bodies involved in high rise projects about the suitability of some insulation types. ” specifically citing PIR and PUR, but not phenolic.

    Again, very interesting and either horribly prescient, or a reflection of what everyone was seeing in the years preceding Grenfell, but crucially an admittance that many in the industry had concerns just a few months before the disaster:

    “There are a number of materials that offer limited combustibility and often these are specified. However, in some cases, materials that are less expensive or that offer better thermal performance have been selected at a later stage. This can compromise the safety of the whole building.

    So the challenge facing specifiers and contractors is to find insulating materials which keep the costs of insulating a façade down, but which meet both thermal performance and fire safety requirements.”

  6. Andrew,
    Wonderful articles; I wait for the next.
    One question puzzles me. How did National Class 0 come into being? It is not recognised by Ap. Doc. B as a British Standard. I’m sure I read that Class 0 material must still be tested to BS8414 to be considered MOLC. Just saying it was 0 is meaningless.
    Kevin Ryan

  7. Thanks, Kevin. Class 0 has been around a long time. I was just looking at a paper from 1961 that was comparing it to the American surface spread of flame standard (ASTM E84).

    It seems to be a class invented for lining materials, and is defined in the Approved Document. (AD B2, Appendix A.13).

    You are right that being Class 0 doesn’t make something a MOLC. This is defined carefully in Table A7 of AD B2, and involves much tougher tests which I attempted to describe in an earlier post:


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