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Combustible material: Cladding and Grenfell Tower

Alan Erwin

Of all the questions in the wake of Grenfell, the materials used for the cladding have been at the forefront of industry minds. So what are the legal questions surrounding the choice of system?

While we must wait on Sir Martin Moore-Bick’s inquiry for a clearer understanding of why fire consumed Grenfell Tower so rapidly, attention has focused on the cladding system used in the refurbishment of the building.

The specified cladding involved an insulation system comprising a rigid polyisocyanurate (PIR) foam core between two sheets of aluminium, and an aluminium composite material (ACM) rainscreen consisting of aluminium panels with a polyethylene (PE) core.

What can be said at this stage is that the fire hazards associated with the use of composite cladding panels have long been known about.

In the 2003 case of Sahib Foods Ltd & Anor v Paskin Kyriakides Sands, the court had to consider the liability of an architect where a fire in a gas-heated pan in a room used for vegetable preparation destroyed most of a food factory. The architect had specified composite panels with a polystyrene core.

It was clear from the evidence that the risks of the spread of fire associated with combustible cores such as polystyrene (EPS) and polyurethane (PUR) were known about at the time of specification in 1994. In fact, the manufacturer had warned of the fire risk and recommended a non-combustible (but more expensive) alternative.

‘Not the slightest impressed’

The architect was held liable on the ground that it ought to have warned the client of the risk but failed to do so.

The judge commented that he was “not the slightest impressed by the submission that since the defendants had complied with their statutory requirements and as a result no one was killed or injured they had fully performed their duties”.

The RIBA Journal described the case as “a wake-up call for the industry as a whole”. Despite that, it seems that lessons have not been learned.

It is conceivable that the Grenfell Tower fire may prompt a partial return to the concept of blacklisting ‘deleterious’ materials, at least as far as cladding materials are concerned, but that would be a retrograde step.

Materials are seldom deleterious in themselves, and it is always a question of the circumstances in which they are used. The blacklists of the past tended to ban virtually all the materials likely to be used as cores, including man-made mineral fibres, which may have led to them simply being ignored in practice.

Selecting materials

The better course is to focus on the proper exercise of professional skill and care and the knowledge that should inform the selection of materials.

In this context, the BCO publication Good Practice in the Selection of Construction Materials is often used as a point of reference, although it gives surprisingly little prominence to the subject of cladding materials and fire risk, given the profile of this issue.

What seems clear is that the specification of combustible composite cladding materials in circumstances that present a serious fire risk will expose the specifier to potential negligence claims, whether arising from increased insurance premiums, actual property damage, or even, in an extreme case such as Grenfell Tower, fatalities.

The government has announced a review of the Building Regulations, partly in response to criticism fuelled by a perception that ‘deregulation’ has gone too far.

The part of the regulations which deals with fire safety is Approved Document B, Section 8 of Volume 1 (applicable to dwellings) and Section 12 of Volume 2 (applicable to other buildings). They cover the fire standard for external walls and specify the fire resistance which external walls have to achieve.

Sections 9 and 13 of the respective volumes limit the permitted extent of unprotected areas and treat external walls that have the appropriate fire resistance, but have combustible material more than 1 mm thick as their external surface, as an unprotected area amounting to half the area of the combustible material.

Detailed and prescriptive regulations

Whatever technical criticisms of the relevant regulations may ultimately be made, the charge of a lack of regulation does not really stand up.

The regulations regarding combustibility of external walls are in fact detailed and prescriptive. In any case, the effectiveness of regulations depends on the thoroughness with which they are enforced.

If Grenfell Tower is truly to be a wake-up call, the industry will need to develop a greater professional ethic and resist pressures for short-term cost-cutting at the expense of long-term performance and safety.

Alan Erwin is a partner at Fladgate

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