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Lessons from the Surfside, Miami disaster

Ninety-eight people lost their lives in the shocking collapse of Champlain Towers South in Surfside, Miami, last year. What do we now know about the cause of the collapse, and could it happen again? Rhiannon Curry reports

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The 12-storey seafront Champlain Towers South, in Surfside, Miami, collapsed in the early hours of 24 June 2021 (picture: Alamy)
The 12-storey seafront Champlain Towers South, in Surfside, Miami, collapsed in the early hours of 24 June 2021 (picture: Alamy)
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Ninety-eight people lost their lives in the shocking collapse of Champlain Towers South in Surfside, Miami, last year. What do we now know about the cause of the collapse, and could it happen again? @RhiannonCurry_ reports #UKhousing

On 24 June 2021, at approximately 1.25am, the 12-storey beachfront condominium Champlain Towers South in the Miami suburb of Surfside collapsed, killing 98 people.

The disaster rocked the United States and the wider world – spontaneous collapse of buildings is virtually unheard of in the West. And it plunged the Florida community into a state of profound grief and shock. The 40-year-old building contained 136 apartments and should have stood for many decades more.

In the aftermath of the disaster, many questions about the structure were raised: could corrosion from salt or repeated flooding have weakened its columns? Why, when the initial fault occurred, did the concrete slabs of the building seemingly fail under pressure and detach from the columns?

“For one reason or another, owners often do not indulge in the basic maintenance required to keep water out”

Engineers and construction specialists rushed to establish the implications for many of the US’s other buildings in similar locations and with similar features.

But could such a disaster ever occur in the UK?

Britain is, of course, no stranger to a tragic building collapse: Ronan Point was a 22-storey tower block in Newham, east London, which suffered a partial collapse on 16 May 1968, only two months after opening. A gas explosion resulted in the progressive collapse of an entire corner of the tower block, killing four people and injuring 17 other residents.

The explosion blew out the load-bearing flank walls, which had been supporting the four flats directly above, lifting the ceiling and floor slab. This resulted in a house-of-cards collapse as the floors above them
were then unsupported.


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Theories

A similar issue seems to have been at play in Miami: investigators were quickly able to establish that an initial structural failure towards the bottom of the building had caused the progressive collapse of the rest of the structure.

But what caused that initial failure is not yet clear.

Several theories point to a deterioration in the ground itself and the building’s foundations due to the adverse effects of climate change, which have led to sea level rises along Florida’s coastline.

Christopher Beckett, lecturer in geotechnical engineering at the University of Edinburgh, wrote about the phenomenon for the Institution of Civil Engineers in the aftermath of the disaster.

“Sea level rise results in a saline permeation of the groundwater. However, the foundations can be exposed to additional infiltrating salts through spray, borne by storm winds, and flooding: routes which may have been exacerbated by poor structural design,” he wrote.

“We have buildings right on the beach along the coast, and they are old buildings, but they are doing fine because they are regularly maintained”

John Pistorino, a veteran Miami-based engineer, was hired by an attorney to investigate the causes of the tower’s collapse last year. It has not been disclosed who the attorney is representing. Mr Pistorino brushes aside any notion of climate change as the cause of the issue.

For him, the building’s collapse comes down to poor maintenance.

“For one reason or another, owners often do not indulge in the basic maintenance required to keep water out,” he tells Inside Housing from his Miami office.

“We’ve found that if buildings are painted on a regular basis, particularly in coastal areas, perhaps every seven years or so, then the paint acts as waterproofing. This keeps the water out of the steel and concrete.”

He acknowledges that this could cost building owners “hundreds of thousands of dollars”, but that this relatively simple fix ensures buildings stay watertight, even in Florida’s wet conditions.

Building checks

His firm, Pistorino & Alam Consulting, has been checking hundreds of buildings in the wake of the Champlain Towers South collapse for similar issues.

“We have buildings right on the beach along the coast, and they are old buildings, but they are doing fine because they are regularly maintained,” he says.

“Often these are buildings such as hotels, which owners want to look nice for customers.”

Condominium blocks are often owned piecemeal by their residents, which can make dealing with necessary planned maintenance difficult.

It was partly this theory that meant after the Surfside disaster, Florida brought in a new Condominium Act, mandating structural inspections for condominium and co-operative buildings that are three storeys or more in height, as well as more regular inspections for buildings within three miles of the coast.

“While original design flaws alone were unlikely to have initiated the collapse that happened 40 years after construction, engineers consulted by the Herald said the deficiencies, in combination with concrete deterioration, could have been the difference between a single floor caving in and the kind of progressive collapse that killed 98 people”

It also contains a requirement for funding to be reserved for the surveys, as well as any associated maintenance.

Such surveys might have identified problems with the building’s structure that could have existed for many years, a report in the Miami Herald claimed last year, based on interviews with engineers and construction experts.

According to the report, the initial plans for the building, drawn up by a firm called Breiterman, Jurado and Associates that no longer exists, specified structural columns that were too narrow to accommodate enough rebar, or reinforcing steel.

This meant that contractors had to choose between cramming extra steel into a too-small column – which can create air pockets that accelerate corrosion – or inadequately attaching floor slabs to their supports, the report found.

The Miami Herald reported: “While original design flaws alone were unlikely to have initiated the collapse that happened 40 years after construction, engineers consulted by the Herald said the deficiencies, in combination with concrete deterioration, could have been the difference between a single floor caving in and the kind of progressive collapse that killed 98 people.”

Building codes have become much more stringent in the past four decades, requiring stronger steel reinforcement and concrete less susceptible to salt water intrusion, meaning newer buildings are unlikely to have these issues. But the implication is that many thousands of older buildings in Miami and across the world could still be at risk.

“If you look at any of our buildings along the South Coast of England, for example, in Brighton or Bournemouth, you find those that are right on the coast have a terrible problem of corrosion where you’ve got fixings”

In the UK, the British building and engineering world was shocked at the scale and speed of the collapse, says Gary Strong, global building standards director at the Royal Institution of Chartered Surveyors.

“Everybody has been really keen to find out more about why it happened because it was so catastrophic in terms of the progressive collapse.”

Various committees he sits on have debated the issue, trying to work out whether there needs to be a change in existing legislation in the UK, he explains.

But he thinks that the chances of a similar event occurring in the UK are limited by the house-buying system.

“I think we’re fairly sophisticated, particularly for residential buildings, in the sense that there’s always a mortgage valuation going through somewhere, so a surveyor is going to look at buildings and they are trained to look for things like cracks.”

A structural failure near the bottom of Champlain Towers South caused the progressive collapse of the rest of the structure (picture: Alamy)
A structural failure near the bottom of Champlain Towers South caused the progressive collapse of the rest of the structure (picture: Alamy)

Ronan Point

Ronan Point has also influenced much of what we know about maintaining tower blocks.

“There’s been a lot of work around LPS – large panel system – concrete towers,” Mr Strong explains.

“After Ronan Point, a lot of repairs were done to these towers but they weren’t repaired very well actually, which has come out in the wash, and some have since been demolished.

“The engineering and surveying community is pretty alert to all of this.”

From a climate point of view, UK buildings are less susceptible to salt water corrosion because we have lower humidity than Florida, meaning there is less salt in the air.

But it is not totally unheard of.

“If you look at any of our buildings along the South Coast of England, for example, in Brighton or Bournemouth, you find those that are right on the coast have a terrible problem of corrosion where you’ve got fixings,” says Mr Strong.

“Often these are holding the balustrade on balconies, for example, and you’ll see that they haven’t used stainless steel so they’re corroding badly.”

From his understanding, although Inside Housing has not seen independent verification of this claim, there were issues flagged up with the Miami tower block years before the collapse occurred, particularly with the pool deck, which appeared to be sagging.

The building’s managing agent did not respond to a request for comment relating to these issues.

But it could take years to establish the real cause.

“There are millions of high-rise condominium units in Florida alone, many of them ageing structures near the ocean. While a NIST investigation is intended to identify the cause of the Champlain Towers South collapse, it could also uncover potential issues in other similar buildings nearby and throughout the nation”

Since the disaster, the evidence, including structural components such as concrete columns from both the collapsed and imploded portions of the building, has been preserved in a secure warehouse in Miami-Dade County.

Experts have been carefully cataloguing and analysing the materials, as well as collecting detailed measurements and creating 3D models for further testing.

The National Institute of Standards and Technology (NIST), which is leading the federal investigation into the collapse, is set to begin invasive testing on samples of material from the collapse site in the coming weeks.

Glenn Bell, co-lead of the investigation, says: “Invasive testing will provide important information about the properties of the concrete and reinforcing steel, and the potential roles those properties may have played in the collapse.

“This is an important step in the investigation, one we are able to take only after months of careful investigation and preparation.”

In its initial report issued after the disaster, NIST said: “There are millions of high-rise condominium units in Florida alone, many of them ageing structures near the ocean. While a NIST investigation is intended to identify the cause of the Champlain Towers South collapse, it could also uncover potential issues in other similar buildings nearby and throughout the nation.”

Anyone involved in building or maintaining properties will surely be watching with interest, conscious that the effects of the Champlain Towers disaster could reverberate around the world for years to come.

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