Getting cladding right
25 May 2021, Paul Finch
The ongoing nightmare of people living in apartment blocks, with cladding comprising what should correctly be called ‘aluminium composite products’ continues to haunt not just their waking hours, but that of government ministers who seem caught in the headlights about how to handle this, writes Paul Finch.
It doesn’t help that actions to date have implied that acp cladding is dangerous in all circumstances. This is simply not true. Consider the following: a competent design complying with all regulations at the time was built as designed. The appropriate cavity barriers/fire stops were incorporated. The core ‘filler’ material within the aluminium contained a fire retardant. In these circumstances, the residents can probably rest easy. Once the appropriate surveys have been carried out to verify all of the above, there should be no need to demolish/replace anything, at least externally. It doesn’t matter whether the building is low, medium or high-rise.
Because so-called ‘aluminium-composite material’ has now been banned isn’t relevant (actually there is no such thing as ‘acm’, which implies an actual material. There is aluminium and its filler core). The safety factor overcomes the danger factor, the former comprising the cavity barriers, fire stops and fire retardant.
The reason we can feel comfortable flying in aeroplanes is the same: we have faith in the science that has made travel in a thin metal tube an acceptable risk, even though the tube offers little or no protection in the case of impact, and the whole would explode given half a chance. In short, we need the appliance of science to understand the risks involved in the relatively straightforward matter of cladding apartment blocks.
As an example of how rationality can be applied to regulation and materials, I recall a talk at the RIBA by Arup’s former fire guru, Margaret Law. She talked about the proposed design of Mound Stand at Lord’s cricket ground, by Hopkins Architects, which envisaged an ETFE roof. What would happen if this caught fire? Answer: it would drip molten plastic material onto the heads of anyone unwise enough still to be sitting underneath it. So should it be allowed?
Arup did their sums. What they wanted to know was what temperature would be required to set the roof ablaze, to the point where it would melt. The conclusion was that it would require a major accident – for example a petrol tanker crashing immediately outside the ground, triggering an explosion which would result in a petroleum-driven inferno.
How likely would such an event be? Arup then checked fire records for, if I remember, 50 major cities around the world, going back several decades, to see how many such incidents had taken place. The answer was none. The conclusion was that the likelihood of a catastrophic fire was hugely outweighed by evidence-based history, and regulatory approval was obtained for that excellent building.
The truth is that everything will burn, it is a question of how to prevent or mitigate the impacts of fir in the first place. Government and ministers are on the hook because they know that on the watch of the political class, things have gone horribly wrong with the construction sector in recent decades. Poor design, cynical and incompetent building, risk transfer, mendacious product performance claims and a failed testing system cannot be the fault of the luckless tenants and leaseholders, who find themselves financially responsible for the making safe of buildings they do not own.
Ambiguity in the official government advice on how to comply with fire regulations makes it inevitable that the taxpayer is going to carry the can on all this, and billions have been set aside for it. So it is important that we don’t punish ourselves twice: first financially, and then again by making irrational decisions about materials and products.
Timber construction is environmentally high desirable (especially if it involves bamboo), yet the rush to ban its use following a single apartment fire involving timber balconies is another example of acting in haste in order to repent at leisure. We all know that, in general, timber behaves well in fires. Knee-jerk responses in matters of science never make sense.
A Nylon comparison
Excellent to see that Thomas Heatherwick’s New York pier park has opened to public acclaim, despite a vindictive campaign to stop it in its tracks. Most of the funding has come from private sources, as would have been the case had we built his Garden Bridge across the Thames. This all shows that while London procrastinates and prevaricates, in the grip of a Miserabilist Tendency devoid of imagination or ambition, the Big Apple just gets on with it. Good for them, but not for us.
Mind your language
The diversity director of the RIBA tells us we shouldn’t be using the word BAME to describe black and minority ethnic folk, but identify individual groups instead. Presumably a list is available somewhere. Meanwhile ‘white’ will have to cover everyone from blonde Scandis to swarthy Southern Italians. Hey ho.