What caused the Grenfell fire? Here’s what we know

Never again. Image: EPA/Neil Hall.

The Grenfell Tower fire resulted in the greatest loss of life from a fire in Britain since World War II. A year on, we know that the fire’s rapid spread was at least partly due to the cladding that enveloped the building. Although a public inquiry is ongoing, and we’re still waiting for the full results of forensic evidence, there is no doubt that changes are needed to prevent this catastrophe from happening again.

This includes new regulation for high-rise buildings and the use of flammable materials in their construction. In addition, experts and researchers in fire safety need to work more closely with the government and construction companies. More immediately, for buildings similar to Grenfell, that were built according to old regulations, simple and immediate actions should take place now. Evacuation routes, sprinklers and fire retardant materials need to be installed as quickly as possible.

Construction problems

Grenfell Tower was built in 1974 and contained 120 flats, housing between 400 and 600 people. It was like a small vertical village. In 2016, the building was refurbished at a cost of £8.6m; this was when the cladding was introduced.

From the first media reports on the morning of 14 June 2017, engineers and scientists raised concerns over how quickly the fire spread, especially on the outside of the building.

It seemed that the fire was unable to be contained within a compartment. The concept of compartmentation in fire engineering is widely used in constructing buildings. By adding fire barriers, often fire resistant doors, fires are supposed to stop spreading quickly and so allow time for evacuation and treatment. But at Grenfell this did not happen: the fire quickly found access to the outer side of the building. Something had gone horribly wrong and the fire safety advice to residents to stay inside has since come under scrutiny.

The flammable cladding was instrumental in the fire spreading so quickly. Image: Flickr/ChiralJohn/creative commons.

Immediately, the focus was put on the new exterior skin (cladding). This not only contained flammable materials (polyethylene insulation covered by thin aluminium sheets that buckle in high temperatures and expose the internal material to flames), but was also installed onto the existing incombustible reinforced-concrete structure, in a way that left a gap between the facade and the building’s structure. This enabled what is known as the “chimney effect”. Put simply, the gap between the facade and the structural skeleton of the building meant that the fire sought oxygen and quickly travelled vertically, while burning more of the flammable skin.

It seems that the facade system, even if it was designed according to some regulations, did not perform properly. Such a catastrophic failure can never be the result of one single factor but rather was a chain of unforeseen events happening all at the same time.

Making sure it doesn’t happen again

Materials are still being fire-tested and several blocks remain evacuated. But although changes to building regulations are likely, these changes have yet to happened. This is partly because of the sheer complexity of the issue.

But some of the regulations that need to be implemented are clear. For a start, each type of building should be designed or refurbished with the appropriate regulation. So for example, all buildings that are higher than five stories ought to be provided with alternative evacuation routes such as more (or external) staircases, be equipped with sprinklers, and only be allowed to use fire-retardant materials, such as cementitious boards, ceramics, or glass facades.


Buildings like Grenfell should further be equipped with more sophisticated early warning systems that can detect the smoke and fire early enough. Not only could these systems set the alarm on and activate the sprinklers, but they could also restrict the fire within an area by making the building “active”. This could include automatically closing windows and self-controlled ventilation systems and elevators.

Another major positive change for tall residential buildings, would be the increasing use of performance-based fire resistance design. This is when each particular building is designed so that it performs under certain safety and strength criteria, allowing engineers to fully understand how the building will respond thermally and structurally to a fire incident.

Currently in the UK, for some buildings a general prescriptive-based approach is followed, which simply states how a building is to be constructed. The problem with prescriptive guidelines is that engineers ignore the actual response of the building and the effect of real fires, making the level of safety and robustness an unknown. Although this might be more costly in time and expense, when you have so many people living in one building it is necessary.

Each building design is also a different entity with its own limitations. So each building should be treated accordingly.

Collaboration and communication

Forensic evidence is still being collected and preserved. Once all the evidence is in, researchers and investigators will be able to review the causes and reasons why the fire spread in more detail. But right now we still do not have a deep enough understanding of the flammability of the facade systems, or the toxicity of the materials used.

Once we do, collaboration between academic researchers and companies producing cladding and other construction materials will be key. This is the only way of ensuring that products are developed to meet or exceed rigorous safety standards when put under pressure. This will be crucial for giving housing residents and the public greater confidence. Better communication between building regulators, local authorities, manufacturers, developers, and designers is also important.

The ConversationWe must start rehabilitating tall residential buildings as soon as possible, before another disaster occurs. And out of this tragedy must come long lasting changes to the design of buildings, the construction materials used, and the way they are applied.

Konstantinos Daniel Tsavdaridis, Associate Professor of Structural Engineering, University of Leeds.

This article was originally published on The Conversation. Read the original article.

 
 
 
 

What's actually in the UK government’s bailout package for Transport for London?

Wood Green Underground station, north London. Image: Getty.

On 14 May, hours before London’s transport authority ran out of money, the British government agreed to a financial rescue package. Many details of that bailout – its size, the fact it was roughly two-thirds cash and one-third loan, many conditions attached – have been known about for weeks. 

But the information was filtered through spokespeople, because the exact terms of the deal had not been published. This was clearly a source of frustration for London’s mayor Sadiq Khan, who stood to take the political heat for some of the ensuing cuts (to free travel for the old or young, say), but had no way of backing up his contention that the British government made him do it.

That changed Tuesday when Transport for London published this month's board papers, which include a copy of the letter in which transport secretary Grant Shapps sets out the exact terms of the bailout deal. You can read the whole thing here, if you’re so minded, but here are the three big things revealed in the new disclosure.

Firstly, there’s some flexibility in the size of the deal. The bailout was reported to be worth £1.6 billion, significantly less than the £1.9 billion that TfL wanted. In his letter, Shapps spells it out: “To the extent that the actual funding shortfall is greater or lesser than £1.6bn then the amount of Extraordinary Grant and TfL borrowing will increase pro rata, up to a maximum of £1.9bn in aggregate or reduce pro rata accordingly”. 

To put that in English, London’s transport network will not be grinding to a halt because the government didn’t believe TfL about how much money it would need. Up to a point, the money will be available without further negotiations.

The second big takeaway from these board papers is that negotiations will be going on anyway. This bail out is meant to keep TfL rolling until 17 October; but because the agency gets around three-quarters of its revenues from fares, and because the pandemic means fares are likely to be depressed for the foreseeable future, it’s not clear what is meant to happen after that. Social distancing, the board papers note, means that the network will only be able to handle 13 to 20% of normal passenger numbers, even when every service is running.


Shapps’ letter doesn’t answer this question, but it does at least give a sense of when an answer may be forthcoming. It promises “an immediate and broad ranging government-led review of TfL’s future financial position and future financial structure”, which will publish detailed recommendations by the end of August. That will take in fares, operating efficiencies, capital expenditure, “the current fiscal devolution arrangements” – basically, everything. 

The third thing we leaned from that letter is that, to the first approximation, every change to London’s transport policy that is now being rushed through was an explicit condition of this deal. Segregated cycle lanes, pavement extensions and road closures? All in there. So are the suspension of free travel for people under 18, or free peak-hours travel for those over 60. So are increases in the level of the congestion charge.

Many of these changes may be unpopular, but we now know they are not being embraced by London’s mayor entirely on their own merit: They’re being pushed by the Department of Transport as a condition of receiving the bailout. No wonder Khan was miffed that the latter hadn’t been published.

Jonn Elledge was founding editor of CityMetric. He is on Twitter as @jonnelledge and on Facebook as JonnElledgeWrites.