When the smoke has cleared

Teodora Lyubomirova looks at the likely impact of the Grenfell Tower investigation on the building industry, and what it means for the future of refurbishment.

If the Ronan Point explosion dealt the blow that transformed building codes in the early 1970s, Grenfell Tower will likely force another sea change in the industry’s approach to large- scale tower refurbishments. The deadly blaze exposed such a wide array of issues that it could be years until all questions raised in the aftermath of the disaster are adequately answered.

However, along with the socio-political rift dividing the country, it’s the design and construction practices employed during the tower’s 2016 refurbishment that have recently begun to come under national scrutiny. While the scope of the public inquiry is yet to be fully defined – and any formal conclusions many months away – industry professionals are asking valid questions about the fitness for purpose of regulations, specification practices and workmanship for future regeneration schemes.

Guidance & deregulation

Among the fevered political controversy and array of questions hanging over the industry, some of the most uncomfortable and yet crucial for future schemes are the issues around accountability (or lack of it), together with the vagueness of the current regulatory framework and a concurrent variance in interpretation.

One thing that is now widely known is that Grenfell’s cladding comprised Reynobond aluminium composite material (ACM) panels with a flammable polyethylene (PE) core to give rigidity, while combustible Celotex RS5000 insulation boards (now withdrawn from sale by Saint-Gobain on buildings over 18 metres) were fixed on the external concrete facade. The choice of this combination may have raised eyebrows outside the industry, but so has the revelation of the complex web of subcontractors typically commissioned on such projects and how it might have the potential to obscure accountability in building design.

Co-founder of campaigning architectural practice Architects for Social Housing (ASH) Simon Elmer suggests that in the era of PFI and design and build contracts, the industry should treat the disaster as a wake up call.

“What we are concerned about is that you would have an architect to oversee a refurbishment like this from the beginning to the end. What’s happened through privatisation is there’s no single person or organisation that is responsible for overseeing the whole thing – the architects have no contractual authority over those who are carrying out the work.” He adds: “The people who are actually making the final decision about fire safety or materials used are not professionals, but it’s the client, who has no professional expertise at all.”

The sandwich panels found on Grenfell – and subsequently on hundreds other towers following the Government’s somewhat knee-jerk response of mass testing of samples – have since been ruled unsuitable for use on tall buildings because of that combustible PE filler. The bigger issue however is how guidance has been interpreted with regards to such products. As structural engineer Arnold Tarling, an associate director of Hindwoods Chartered Surveyors and a member of the Association for Specialist Fire Protection, gave a stark revelation to ITV in June:

“The Building Regulations are not fit for purpose with regards to this form of cladding. All that you require to meet the standards is that the outside surface shouldn’t allow the spread of flames. What is going on behind the metal or the other surface is entirely irrele- vant to Building Regulations.”

In essence, the loose (and potentially loosely interpreted) recommendations within the Regs meant that manufacturers could see their products legitimately specified on Class 0 surface spread of flame criteria, because a metal skin encased the flammable PE filler. However, in the wake of Grenfell the Government issued an ‘Explanatory Note’ as an attempt to provide some clarity on interpreting the guidance, saying the whole of an external cladding product had to pass its ‘limited combustibility’ criteria – fillers as well as skin.

This conclusion was backed up by the 100 per cent fail rate of cladding samples, which were sent by landlords to the testing facil- ities at the Building Research Establishment (BRE) in the immediate aftermath of the fire.

However, following criticism from the expert advisory panel chaired by former London Fire Commissioner Sir Ken Knight, BRE has since tested the insulation alongside the cladding panels to establish how it performs as one system – and so far at least 82 tower blocks have failed under the new testing. What’s more, according to evidence released by BRE, it took just over seven minutes for the fire to reach the top of the nine-metre test wall (clad in a combination of ACM with a PE filler, and PIR foam insulation) via the ventilation gap, bypassing the stone wool cavity barriers and forcing the researchers to terminate the test long before the required minimum duration of 40 minutes.

A review of Building Regulations has now been commissioned by DCLG, headed by former Health and Safety Executive chair Judith Hackitt, who is currently chair of the Engineering Employers Federation. It will examine the “regulatory system around the design, construction and ongoing management of buildings in relation to fire safety,” as well as “related compliance and enforcement issues” It will report “no later than spring 2018.”

Minding the gaps

Analysis of initial design plans for Grenfell have raised questions about the design decisions taken, notwithstanding confusion over product specification. According to ASH’s ‘The Truth about Grenfell’ report, a reconfiguration of the windows as part of the 2016 refurbishment ‘pulled’ windows forwards out of their origi- nal frames and fixed them with metal brackets to the external concrete facade, the resulting ‘interface gap’ and the ‘material fillings’ being the only barrier that could stop a fire bursting out of a flat and reaching the external cladding.

Former architect Ian Abley, a technical designer at Audacity, has examined how the ventilation gap between the external insulation and the cladding could have created the ‘chimney effect’ that potentially helped the rapid fire spread upwards and sideways. Abley is quoted in the report:

“Once inside the rainscreen, having bypassed the window, the fire could spread via variously combustible products. Fire would bypass any cavity fire barriers installed…fire in the cladding and involving the insulation might be able to break back into flats at every level through the same interface gap around the window frames, filled with several other materials.”

It is unclear how these gaps were detailed and filled in the event, however images of the overclad tower are thought to show even wider gaps between the cladding and the tower’s concrete columns that could have aided the rapid spread of flames towards the upper storeys.

Holistic approach

While it is a matter for the police and the public inquiry to provide official conclusions on the case, it is clear that the refurbishment and how it affected the safety of the tower will be of paramount importance. At a public meeting organised by Architects for Social Housing in a bid to provide expert advice to the Justice 4 Grenfell community group on various aspects of the refurbishment, co-founder of ASH, architect Geraldine Dening said:

“When you change one aspect of the building, you need to change the way you think about it holistically. That’s absolutely crucial for people to understand – when altering a building, they change how it operates as a system.”

The inquiry is very likely to look at not only the 2016 refurbishment, but also into past alterations of the building and the role of various bodies responsible for the upkeep of the tower. It has become evident that ‘improvements’ for residents scarcely justified the label – the alleged unlawful additions of unenclosed gas pipes on the walls of the escape routes and the lack of adequate lighting on the main stairwell are just two examples. It is not widely known that the tower had been earmarked for demolition back in 2009 when plans for the Lancaster West Estate regeneration were being set out. While these intentions were never realised, the tower’s appearance remained a key concern which the subsequent overcladding was meant to address. It is also worth noting that a 2010 lift lobby fire at Grenfell Tower was contained, with the compartmentation performing as intended.

The report by the ASH architects questions whether the motives behind many regeneration projects are more about increasing asset value than resident benefit, but also expresses worries that politi- cians might decide to scrap the regeneration of existing buildings following Grenfell, and issue a ‘demolition decree’ that will see estates torn down. Elmer comments:

“We are very concerned that the council and Government might use this disaster and state the estate regeneration and refurbishments are not viable or safe and use this to actually demolish the rest of the Lancaster West Estate.”

He added:

“We are concerned that politicians are going to say that 1960s and 1970s estates cannot be refurbished and must therefore be demolished and redeveloped in what is already a very cynical programme to promote estate demolition.”

Elmer concludes:

“That’s why we’ve gone to such length to show that the cause of this fire was not the design of this building or its built quality – what was wrong was the refurbishment.”

LIKELY SCOPE OF THE PUBLIC INQUIRY

  • How the fire started and how it spread, and why so many diedThe construction of the building and its modification over the years
  • The relevant building and fire regulations
  • The involvement of the local authority and TMO (tenant management organisation)
  • The role of the architects, contractors and manufacturers
  • The fire safety measures taken over the years
  • The warnings voiced by the residents about the fire risks, and responses by the council and TMO
  • Fire Brigade response