Grenfell Tower: Exova’s approval in 2012 of the use of combustible ACM for high rise cladding

In my last post I introduced a Certificate of Approval, issued in 2012 by Exova, trading as Warrington Certification, for a combustible FR grade ACM panel. According to the government’s post-Grenfell interpretation of Approved Document B2, 12.7, this certificate should not have been issued, since the panels fail to meet the limited combustibility requirement of that paragraph.

The certificate bore on every page the signature of Sir Ken Knight, who is Chair of the Grenfell Tower Expert Panel. This body claimed on 30 June 2017 that the Buildings Regulation guidance requires the ACM core to be of limited combustibility. The text of the Approved Document guidance on cladding has remained unchanged since 2007. It follows that the Expert Panel must be of the view that the certificate was issued in error.

This puts Sir Ken Knight, as one of the two signatories to the certificate, in a difficult if not untenable position. Pete Apps for Inside Housing published a story about the certificate, with responses from Exova and the government but not from Knight himself. The MHCLG appeared to distance Knight from the certificate, claiming that his role was only ‘to sign off the impartiality of the certification scheme as a whole’, and that he was ‘not approving specific cladding systems’:

Does the MHCLG believe then that the certificate was in error? And more importantly, is this Sir Ken Knight’s view? If so, given that it carries his signature on every page, it is surely beholden upon him to say so.

Exova’s response

Exova, on the other hand, in its response to Inside Housing, stood by the certificate it issued, and claimed that it had not certified the product for use above 18 metres. There were other conditions that would have to be met, including the limited combustibility requirement of 12.7:

But this is absurd. Even the very name of the product, ‘Alubond usa FR Euroclass B’, declares that it is not of limited combustibility, and so could not meet that condition, by its very nature:

It would be like giving the vote to seventeen year olds, on condition that they are eighteen years or older!

The approval for use over 18 metres

The Certificate of Approval

relates to the use

of the product, which had demonstrated a Class 0 fire performance in accordance to Warrington Certification’s own Technical Schedule 19.

The Certificate is held on the online CERTIFIRE Register, in the section for approvals to Class 0 and Class 1. Exova state that

the complete field of application for products

is included, so that the specifier or enforcement authority can

check the suitability of a product for the intended end-use application.

The Field of Application for this combustible ACM product begins on page 3 of the certificate:

A Class 0 material may be used, according to the certificate, on

external surfaces of multi-storey buildings above 18m high

providing that cavity barriers are fitted in accordance to Section 9 of Approved Document B. This approval for use on ‘external surfaces’ of high buildings relates to AD B2, 12.6, headed ‘External Surfaces’:

and Diagram 40e:

which requires materials used for the external surfaces to be Class 0 above 18 metres (with a concession for steel sheet with a thin organic coating).

The single condition stated, that cavity barriers be fitted in accordance with Section 9, relates to paragraph 12.8:

which corresponds to the fourth stated Field Of Application:

Exova are claiming that there was a further condition to using the product on high buildings, namely that it also fulfilled the requirements of 12.7:

There are three immediate problems with this:

1) The clause does not appear to apply to ACM panels, which serve no insulation function when used on external walls.

2) In contrast to the cavity barrier condition, which is capable of fulfillment, this condition cannot be fulfilled, since the product is Euro Class B, and therefore not of limited combustibility, as defined in AD B2, Table A7.

3) It seems unreasonable, having stated the permission based on 12.6, to state the condition contained in 12.8, but omit the condition allegedly contained in  12.7.

Moreover, as I now explain, it seems to me that the addition of one or more stated conditions to a permission, indicates strongly that there are no further conditions in view.

Permissions with stated conditions

My parents used to let me watch Match of the Day as a boy providing that I changed into my pyjamas first. When I came down to watch the game in my pyjamas, did they then ask me if I had tidied my room, or cleaned my shoes, or set some additional condition which had to be met before I was allowed to watch the football? Would that have been legitimate? Or would they in fact have been breaking their word?

‘Providing that’ means ‘With the proviso or stipulation that, on the condition or understanding that’ and is equivalent to ‘provided that’:

The most recent illustration of its use in the Oxford English Dictionary is from a tenancy agreement:

The bond, or ‘deposit’ as we say here, will be returned providing that the house is left in good condition. When the tenant comes to hand over the keys, can the landlord add a further condition before returning the money?

Dear reader, here is the approval from the Certificate:

... a material with a fire performance classification of Class 0 may be used ... On external surfaces of multi-storey buildings above 18m high providing that cavity barriers are in situ which comply with Section 9 of Approved Document B of the Building Regulations of England and Wales 2006.

It seems to me that the stated condition is both necessary and sufficient. If it is complied with, then the Class 0 material may be used above 18 metres. This is stated clearly and unambiguously.

Is the approval for this specific product?

I explained above that

the complete field of application for products

is included in the Certifire Certificates of Approvals, from which it follows that the Field of Application should be for this specific product. Nevertheless it may be objected that, as written, the Field of Application is for Class 0 materials in general:

Could it be that one or more of the stated uses is not relevant to this specific product? This potential objection would gain weight if one or more of the other three stated uses was not relevant to the product:

The last of these is merely a variation of the rainscreen cladding use that we are  discussing. While the application is perhaps less familiar, ACM panels are used on interior walls:

as well as other interior applications including suspended ceilings, as shown in this technical brochure for Alpolic:

Table A3 of Approved Document B2 contains requirements for the upper surface of fire-resistant suspended ceilings to be Class 0:

which I am fairly sure (but stand to be corrected) corresponds to the second stated use of the product:

I can see no reason to doubt, therefore, that the Field Of Application constitutes an approval of this combustible FR ACM for all four stated uses, including high rise cladding.

Andrew Chapman



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Andrew Chapman

I live for Jesus. He is my life, my hope, my Saviour and Redeemer and Lord. Hallelujah! God has blessed me with a wonderful wife called Alison, and we serve the Lord together with gladness and joy. Pray for us that we may fulfill our calling and persevere to the end on the narrow path that leads to life.

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