The freelance designer who was brought on board at cladding subcontractor Harley to produce fabrication drawings for the refurbishment of Grenfell Tower, based on architect Studio E’s plans, has complained of a “total lack of clarity” in the Building Regulations.

Kevin Lamb’s comments came after he was asked by counsel to
the Inquiry Kate Grange QC, in a hearing yesterday (17 September) about his work
on the project.

Lamb was brought in as a freelance project designer on the Grenfell
Tower refurbishment, having previously worked for Harley on the Chalcots Estate
in London.

Cavity barriers

Grange asked Lamb about his understanding of Approved
Document B, and specifically whether or not he was clear that diagram 33 in the
document showed that window openings should be closed with cavity barriers to
prevent the unseen spread of fire and smoke within concealed spaces of a
building’s external cavity. Lamb agreed that it did “in this instance”.

But Lamb said he regarded cavity barriers being provided
around window openings as “one route to compliance”.

Grange asked if this meant that Lamb thought there could be
a “fire-engineered” solution by a fire engineer that designed the external wall
in a way that was “different to Approved Document B but still meets the
functional requirements of the Building Regulations”, Lamb replied that he thought
it did.

Asked if on Grenfell he thought he was following Approved
Document B and the main guidance that he had, or if he thought there had been a
holistic, fire-engineered approach to the external wall, Lamb said: “I didn’t
give it a vast amount of thought, but I did know that the architect was backed
up with a fire engineer. We followed the architect’s advice.”

Grange continued: “Did you ever consider that what you were
doing at Grenfell made it difficult for you to comply with the requirement for
cavity barriers around windows?”

Lamb replied: “Yes, because of the shape of the cladding,
there wasn’t a simple way of sealing the perimeter adequately…But it’s quite
clear, because of the design of the building, it wasn’t a simple solution, so
one would imagine that the architect had taken steps to consider another
solution. This may well have been a fire -engineered solution.”

Design not queried with architect

Asked if he ever expressly queried with the architect
whether or not cavity barriers should be included and if so where, Lamb said: “Not
specifically, no, but it was raised internally and we did start various email
trails on that.”

Pressing the point, Inquiry chair Sir Martin Moore-Bick
later asked: “It sounds from what you’ve told us already that there was some
debate within Harley, to which you were a party, as to what these drawings did
actually show…And you didn’t think it appropriate to say, ‘Well, I really need
to hear from the architect so I can do the right sort of drawing’?”

Lamb said: “No, I didn’t. I was happy with the advice from
Harley…They were the cladding specialists. They obviously felt it wasn’t
necessary or they’d had discussions, I don’t know.”

Grange then asked Lamb: “Did you get the impression during the discussion that it was more convenient for Harley not to install cavity barriers around the windows because actually it was quite a fiddly, difficult thing to get right, and that they were looking for a way of deciding that they didn’t have to provide them round the windows?”

Lamb replied: “That’s definitely not the way they would
operate.”

At the end of the hearing, Lamb was asked if there was
anything he would have done differently, knowing what is known now.

Lamb said: “I was a freelance design resource, I don’t think
there was anything different I could have done.”

But he criticised the “total lack of clarity” in the
Building Regulations. “I really think something needs to be done just to take
the ambiguity out of the documentation that everyone is expected to conform to,”
he said.

The Inquiry continues.