Grenfell: Architect’s confidence in Celotex insulation ‘a major failure’

Architect Studio E’s confidence in the combustible Celotex polyisocyanurate insulation specified to be used behind the ACM rainscreen cladding panels during the refurbishment of Grenfell Tower represented a “major failure”, the Grenfell Tower Inquiry has heard.

Expert witness Paul Hyett, a former president of the Royal
Institute of British Architects (RIBA) and a former principal of HKS
Architects, was giving evidence to the Inquiry for a second day, having
produced a report for the Inquiry.

In his report, Hyett said: “It [Celotex 5000] did not meet
any of the definitions for materials of limited combustibility as set out in
Table A7 of Approved Document B2. Studio E should not have specified an
insulation product that did not carry proper certification as evidence of its suitability
in meeting the guidelines of ADB2 and the requirements of the Building
Regulations.”

He added: “Studio E’s continued confidence in the Celotex RS5000 product, and the use of PIR insulation within the cladding system, represents an ongoing major failure on their part to understand both the requirements of the Building Regulations and the guidance given within ADB2 with respect to insulation in external walls. That failure of understanding appears to have extended to both [cladding subcontractor] Harley (Mr Daniel Anketell-Jones) and, surprisingly , [fire consultant] Exova (Mr Ashton).”

Hyett agreed with lead counsel to the Inquiry Richard Millett QC that combustible materials could be incorporated into a rainscreen system in accordance with Approved Document B if the total wall construction underwent a full-scale BS8414 system test and the results met the BR 135 performance criteria, or if a fire engineering approach set out in the Building Control Alliance (BCA) Technical Guidance Note 18 involving either a desktop study or a holistic fire engineering solution was carried out.

But he also agreed that if none of those three alternatives
were adopted as the route to compliance, then the use of PIR or phenolic
insulation was “essentially prohibited” by ADB2.

He confirmed that this meant Studio E should have satisfied
itself that the Celotex FR5000, RS5000 and the Kingspan Kooltherm K15 used on
the building were materials of limited combustibility.

Millett asked: “And from a prudent architect’s point of view, would the prudent architect, if asking someone like Exova or Harley or Rydon, have expected them to have done the same?”

Hyett replied: “Yes.”

Expert ‘astonished’ by fire consultant’s advice

Millett went on to ask Hyett about an extract from an email exchange in September 2014 between Neil Crawford of Studio E and Terry Ashton of Exova. Exova was not retained after main contractor Rydon was appointed in 2014 but continued to give advice on the project. In his report, Hyett noted an answer given by Ashton to a question from Crawford, in which Ashton said: “If the insulation in the cavities behind the rainscreen cladding is combustible you will need to provide cavity barrier as shown on your drawing.”

Hyett said in his report: “Mr Ashton’s reply is astonishing,
coming from an alleged expert in fire safety within construction. By stating: ‘If
the insulation … is combustible’ he appears to be condoning an outright
breach of ADB2 guidance under paragraph 12.7.’

Millett asked: “Now, just looking at that , do you agree that if another route to compliance with the Building Regulations had been adopted, in other words one other than the linear route to compliance under paragraphs 12.6 to 12.9, then incorporation of an insulation which was combustible may not have been a breach of the Building Regulations?”

Hyett replied: “Yes.”

Millett asked: “So is it possible, then, for cladding
systems as a whole to satisfy the B4 requirement by other routes even though
they included combustible products?”

Hyett replied: “I believe that’s correct.”

Millett asked: “Now, if Mr Ashton didn’t know, let’s assume
as a fact at the moment he didn’t know what route to compliance had been
adopted, do you take the view that his response might have been reasonable?”

Hyett replied that he did not believe this. He went on: “Anybody
giving advice like this should understand the context in which the advice is
being given. They should get the information in front of them. He should have already
known that the building was over 18 metres high. If he didn’t, he should have
got the information in front of him. If he had forgotten, he should have reminded
himself. Unqualified advice is just not acceptable. This is very, very serious
territory here. He should have established the facts and then given the advice.
Having established the facts, I think he should have been astonished.”

Turning to ask Hyett about Crawford, Millett asked that if Crawford knew that none of the three alternative routes to compliance was being considered, it would have been reasonable for him to have relied on Ashton’s statement as providing “any kind of comfort to him that he could go ahead and use combustible insulation”.

Hyett replied: “He shouldn’t have accepted such advice. He
should have raised questions.”

Millett asked: “When you say ‘shouldn’t have’, are you
saying that his accepting the advice and not raising questions fell below the
standard of the reasonably competent architect?”

Hyett replied: “Yes, yes, yes.”

ACM cladding

Hyett said he wouldn’t have expected a reasonably competent architect to have known that ACM panels of the type used on the Grenfell Tower refurbishment (Reynobond PE 55) were at the time manufactured with different cores – a polyethylene core and an ‘FR’ (“fire resistant”) core.

However, he said he would have expected an architect
preparing to work on the project to have obtained such knowledge. He also
confirmed that he would have expected a reasonably competent architect to be
aware of the fire performance properties of ACM panels in general.

But Hyett accepted that it was industry practice that ACM
was “commonly prescribed” at the time, and that this would bear on the standard
a reasonably competent architect should be judged when the prescribed it.

Hyett said: “I think we’re comfortable to specify products
which are regularly used. One gains increasing comfort in that way. But there
is still the obligation to check that that product meets the requirements of
ADB2, and it’s specific within that document as to what the performance should
be. So I think a degree of comfort can be obtained or enjoyed by the architect,
but, at the end of the day, they’ve got to be satisfied that the particular manufacturer
and particular product is okay.”

Inquiry chair Sir Martin Moore-Bick asked Hyett if ACM
readily supported combustion.

Hyett replied: “No. I think it’s difficult to get it to
burn, but once it’s burning, it burns with ferocity.” And he confirmed that it
would add significantly to the fire load of the building once burning.

Sir Martin Moore-Bick went on to ask if this was something
architects were generally aware of at the time.

Hyett replied: “We weren’t.”

The ‘pros and cons’ of design and build

In a section of his report discussing the “pros and cons” of
design and build contracts, Hyett noted: “Under traditional procurement the
architect has far greater control for selecting and specifying the buildings materials
and components. Under design and build, the architect usually shows indicative
arrangements which may frequently be less developed at tender stage. He may
frequently be asked to obtain tenders on a variety of options – for example
cladding – as occurred at Grenfell Tower. Indeed, even after appointment the successful
builder may introduce major changes to the specification during design
development and value engineering.”

Millett asked Hyett if it was his opinion that whatever
major changes are made to the specification by the contractor during design development
and value engineering, a reasonably competent architect would see it as their
responsibility to confirm compliance of the materials which are specified with
the Building Regulations.

Hyett replied: “Yes. Of course it depends on the point at which the project is put out to tender, it depends on whether the architect is novated and transfers…responsibility effectively is retained. But essentially the answer is yes.”

Millett asked: “So unless he is specifically instructed, you
say that the architect’s obligation to confirm compliance of the material
specified with the Building Regulations remains undiminished?”

Hyett replied: “If the architect is retained, that is
correct.”

Checks

Millett went on to ask Hyett if he agreed that the design and
builder taking the project on (Studio E was novated to Rydon after it was awarded
the contract) would “have a really thorough check themselves”, but that this wouldn’t
“absolve” the architect from having done its previous check to satisfy itself
that the materials and products it was specifying in the NBS specification were
compliant with the Building Regulations.

Hyett replied: “The issue of checking is I’m sure going to
come up a lot, and I think there’s checking upon checking with this job, and I
don’t like too much checking. What I like is the correct process of analysis at
the right time by the right people. The contractor I don’t think is necessarily
competent to carry out the check, although some contractors employ their own
architects. I don’t think we should assume that they carry out the check. What they
should be doing is satisfying themselves that the work has been thoroughly
checked, and that would take the form of: ‘You guys are coming on board as our architects.
What processes have you been through? Let’s look at some of the issues that have
been developed along the way. We have the following questions from the point at
which we were preparing our tender. We’ll bring them all to the table because
we won the job. Here we go’.”

He added that a competent architect “needs to be checking
their work at every single stage as they go through”.

When it came to subcontractors, Hyett said in his report: “It
is also my opinion that any obligation on the part of the subcontractor to ‘complete
the design in accordance with the designated code of practice’ does not impose
an obligation upon that subcontractor to undertake a checking role or to assume
responsibility for any or all past work of the architect. Further this most
certainly does not exonerate the architect for any design failures in its own
past work that are not ’picked-up’ by the subcontractor.”

But Hyett added: “I don’t want to imply with this that a
subcontractor has no responsibilities for their own work, and it’s important
here to remember that Harley had offered themselves, through their own
documentation, as experts in overcladding buildings… And I don’t think a
subcontractor can just say, ‘Well, we breezed up, we’ve got no responsibility
even to comment on anything, we’ll take it all blind.’ You would expect them to
have some substantial knowledge which they would inform their work with, and
they would raise questions if they thought something was fundamentally wrong.”

The Inquiry continues.