Grenfell Tower: why the ACM panels were in compliance with the building regulations.

The Government testing program

The Grenfell Tower calamity highlighted the possible danger of employing combustible cladding on high rise buildings. Of the two main cladding components, the aluminium polyethylene (PE) composite rainscreen outer cladding panels, and the polyisocyanurate (PIR) insulation boards, it was the ACM panels that have generally been thought – probably rightly in my view, as I have argued previously –  to have been the primary cause of the disastrous rapid spread of the fire over the external surface of the building.

The Government acted with commendable speed and efficiency by requiring Local Authorities and Housing Associations to identify by end of day 19 June any ACM panels in use on their high rise buildings, and to send in samples for testing.

In its letter to the Chief Executives, the Department for Communities and Local Government (DCLG) claimed that to be compliant with ‘Building Regulations guidance’, the core of the panels should be composed of a material of ‘limited combustibility’, as defined in Approved Document B2 at Table A7, or be Euro Class A2 or better:

I outlined the Approved Document guidance for cladding systems in an earlier post. In brief, in AD B2 at 12.5, two routes to compliance are offered:

i) through adherence to the requirements of sub-sections 12.6-9 or;

ii) through large-scale system testing to BS 8414.

The DCLG, in its letter, was in effect assuming that the second route had not been taken, so that it was the requirements of 12.6 to 12.9 that were to be satisfied. In summary, 12.6 specifies that:

external surfaces over 18m should be national Class 0 or Euro Class B or better;

while 12.7 requires that for buildings over 18m:

insulation products, filler material etc should be of ‘limited combustibility’ as defined in the Table A7 mentioned in the DCLG’s letter. A material or product must either be 99% or more inorganic, or pass a 750° C furnace test (BS 476 part 11 or part 4), or have an incombustible core, or be Euro Class A2 or better.

I concluded in an earlier post that of the two main components of the Grenfell Tower system, only the Celotex RS5000 insulation boards were in breach of the Approved Document guidance, since it was only these that were covered by 12.7. The Reynobond PE cladding panels, not being an insulation product, and having a Class B rating, were in compliance with the relevant section, which is 12.6.

It is easy to see the difficulty for the government of admitting that the polyethylene cored cladding panels were compliant with the Approved Document guidance. It had been their responsibility to ensure that the regulations were fit for purpose and did not permit dangerous products to be used. These panels were certainly dangerous, in the use to which they were put. If a way could be found to assert that the regulations did not in fact permit the panels to be used, then this could potentially allow them to escape culpability in this regard.

Moreover, it was no doubt felt to be imperative to get any similar panels off the nations high rise buildings as soon as possible. It would probably be easier to force immediate action if the panels could be deemed to be non-compliant with the official guidance, than if it were admitted that they had been designed and installed in accord with it.

It is not particularly surprising, therefore, that the DCLG is currently pretending (if I may be so bold) that combustible ACM panels are in breach of the Approved Document guidance. In this post, I critically analyse the ways in which the Department has attempted to justify their position.

Continue reading Grenfell Tower: why the ACM panels were in compliance with the building regulations.

Grenfell Tower and the EU: a North-Booker red herring (3/3)

(continued from Part 2)

As a recap, I will try to summarise the position put forward by North and Booker in a number of articles and blog posts:

  1. During 1999-2000 the MPs of the EFRA Committee wanted to replace the existing fire standard EN 13501-1 with one based on a more realistic large-scale test (now BS 8414);
  2. They were unable to do so because as EU members we were obliged to adopt the European standard EN 13501-1;
  3. EN 13501-1 is based on the small-scale surface test EN 13823;
  4. This surface test is quite inadequate to test products with good surface ratings but combustible cores;
  5. If we had been able to make BS 8414 mandatory, then the Grenfell Tower fire would never have happened, since the system employed there would have failed the test;
  6. The EU was laggardly in developing a large-scale test which could then have been made compulsory;
  7. Because of point 2 and point 6, the EU bears a measure of responsibility for the fire.

I pointed out in my last post that in 1999-2000 the cladding regulations were based on four British standards BS 476 parts 7, 6, 11 and 4, and not on any European standard. Nevertheless the European standard was introduced in 2002 and its adoption was indeed compulsory. So the prospect of its adoption could conceivably still have influenced decision-making at an earlier date.

I also showed that the EFRA Committee recommended two routes to compliance:

a) through use of non-combustible materials, or

b) through a large-scale system test.

I then observed that in 2005 Scotland adopted a regulatory approach almost identical to that recommended by the Committee.

Since England and Wales are in the EU as much as Scotland is, it follows that we were also free to adopt this approach.

According to North, EN 13501-1 is based on a surface test only. The question then arises as to how Scotland has implemented their approach, with one route to compliance being through the use of non-combustible materials, if the only test available is a surface test?

The answer, very simply, is that North is mistaken and that EN 13501-1 is a classification standard which ranks construction products according to their performance in two or more of four tests, of which two are surface tests, and two combustibility tests. We are therefore free to raise our regulatory requirements at any time, simply by specifying a higher Euro Class.

I will begin by showing that this has been North’s understanding of EN 13501-1, and then explain the real situation.

Continue reading Grenfell Tower and the EU: a North-Booker red herring (3/3)

Grenfell Tower and the EU: a North-Booker red herring (2/3)

(continued from part 1)

Booker and North’s main argument, as I understand it, is that:

  1. The 1999 EFRA Committee recommended that the BS 8414 large-scale system test should have been made mandatory for cladding systems.
  2. Our membership of the EU prevented this being done.
  3. If it had been done, the Grenfell Tower fire would not have happened.

In this post, I demonstrate that the EFRA Committee did not in fact recommend making the BS 8414 test mandatory. Instead they proposed two alternative routes to compliance:

a) through the use of non-combustible materials;

b) through the BS 8414 test.

I also show that Scotland did adopt a regulatory system of this type in 2005. Since Scotland is in the EU as much as England and Wales are, this in itself rather proves that membership of the EU presented no obstacle to the Westminster government adopting a similar system.

Continue reading Grenfell Tower and the EU: a North-Booker red herring (2/3)

Grenfell Tower and the EU: a North-Booker red herring (1/3)

Christopher Booker has argued (1 July 2017, also here)  that our EU membership has been a contributory factor to the Grenfell Tower disaster. He claims that a Commons committee, set up to investigate the fire risks of cladding on multi-storey blocks, had wanted to replace the European standard EN 13501-1 with the British standard BS 8414, but had been unable to, because of the former standard’s mandatory status in the EU:

Again, as his conclusion, he argues that:

if only full compliance with the BS 8414 standard could have been made mandatory  … that fearful conflagration would never have happened.

This is putting a great deal of responsibility for the Grenfell disaster on our EU membership, an assignment of blame which I believe is entirely misplaced.

Continue reading Grenfell Tower and the EU: a North-Booker red herring (1/3)

Grenfell Tower: was the cladding legal or not (part 3)?

In my previous two posts (part 1, part 2) I have outlined the two routes offered by the Building Regulations 2010 Approved Document B (Vol. 2) at B4 (‘External Fire Spread’) to meet the statutory requirement that:

The external walls of the building shall adequately resist the spread of fire over the walls…

The first route, also sometimes called Option 1, or the ‘linear option’, is to satisfy the requirements of paragraphs 12.6 to 12.9. With regard to the fire properties of materials used in cladding systems for buildings over 18m in height, the requirements are in brief:

a) 12.6. External surfaces should be UK Class 0 OR European Class B or better. The relevant UK tests are BS 476-7 and BS 476-6. The European tests are EN ISO 11925-2 and EN 13823. All four tests are surface tests.

b) 12.7 Insulation products should be of ‘limited combustibility’. They should pass EITHER the BS 476-11 750º C furnace test OR the EN ISO 1182 750º C furnace test OR the EN ISO 1716 calorific test. These are combustibility tests.

The second route, also sometimes called Option 2, is for the entire cladding system to pass a large-scale test to BS 8414.

I will now describe the fire properties of the main two components used in the cladding system at Grenfell Tower, and discuss whether they could satisfy the Approved Document B4 requirements, through either of these two routes.

Continue reading Grenfell Tower: was the cladding legal or not (part 3)?

Grenfell Tower: was the cladding legal or not (part 2)?

In my last post, I pointed out the statutory requirement, contained in Article B4(1) of Schedule 1 of The Building Regulations 2010, that:

The external walls of the building shall adequately resist the spread of fire over the walls…

I then began to examine the guidance given by the government in Approved Document, Volume 2, at the corresponding part B4, as to how this statutory requirement can be met. Two alternative routes to compliance are given in Section 12.5:

In my last post also, I examined the provisions of paragraphs 12.6 to 12.9 and in particular of 12.6 and 12.7 which concern the fire properties of the materials used in construction. I explained that, for buildings over 18m high:

a) The requirement of 12.6 can be satisfied if the materials are UK Class 0. This classification can be achieved through satisfactory performance in two UK fire tests, BS 476 part 7 ‘Surface Spread of Flame’; and part 6 ‘Fire Propagation’. In both of these it is the surface of the board or panel that is subjected to assault by fire.

b) The requirements of 12.7 appear to apply to insulation products only.  The materials must either survive trial by a furnace at 750° C, or have a calorific value of less than 3 MJ/kg. I argue that no material with a substantial component of a polymer like the PIR of the Celotex boards, or the PE of the Reynobond panels, could possibly pass these tests.

In this post I describe the BS 8414 fire test, which is offered as an alternative route to compliance at paragraph 12.5. In following posts I plan to:

Continue reading Grenfell Tower: was the cladding legal or not (part 2)?

Grenfell Tower: was the cladding legal or not (Part 1)?


Philip Hammond, the Chancellor, claimed on the Andrew Marr Show on 18 June 2017 that the cladding that was used on Grenfell tower is banned in the UK:

Was he right?

I will argue here that, from a practical point of view, this flammable cladding cannot legally be used in the UK on buildings over 18m in height. It is not that there is an explicit ban on the material. It is more that there is no way that it could ever meet the requirements of the Building Regulations, at least as interpreted by the standard industry guidance. From a practical point of view, it is not a marginal question. Aluminium composite panels with a polyethylene core are highly combustible and should never be used on high buildings. If, as has been reported, these panels are in place on other tower blocks, they should be removed immediately, or the residents evacuated.

Continue reading Grenfell Tower: was the cladding legal or not (Part 1)?