A Concrete Crisis Has the UK Literally Crumbling

Hundreds of schools, hospitals, and other public buildings made from RAAC, a cheap, lightweight concrete, have to close—the victims of quick fixes and decades of cost-cutting.

As it rolls from one political crisis to another, it’s hard not to think of Britain as metaphorically crumbling. Now, it seems, significant pieces of the country are literally structurally unsound. More than 150 schools, colleges, and nurseries in England have been ordered to close parts of their buildings due to the looming threat of collapse—just days before the start of the new school year. Twenty-seven health care facilities are being urgently reviewed; seven hospitals need to be rebuilt. The cause of the panic is Reinforced Autoclaved Aerated Concrete, whose acronym “RAAC” has suddenly entered the British political vernacular.

RAAC differs from conventional concrete mainly in that it is filled with air bubbles instead of aggregates such as gravel. It’s lighter, easier to build with quickly, and cheaper than other forms of concrete. The air bubbles also provide good thermal insulation, meaning that buildings containing RAAC are easier to heat and cool. It was widely used in postwar Britain all the way up to the 1990s to cast panels for roofs, floors, and walls, and was particularly popular in the public sector, where it was used to rebuild schools, hospitals, and other infrastructure.

But anything cheap and fast comes at a price. RAAC, being less durable than standard concrete, gradually weakens, and the bubbles allow water to seep in. While the steel bars that support the RAAC panels are usually coated with waterproof layers, a lack of maintenance can cause these to corrode, further weakening the panels and causing them to break apart. The lifespan of a RAAC structure is only between 30 and 50 years. That vulnerability has been known about for years. But over the past month, it has taken on the momentum of a present crisis, as it becomes clear just how many important buildings and pieces of infrastructure are well past the end of their shelf life. In addition to schools and hospitals, RAAC issues have been found in theaters, housing blocks, council buildings, and even in London’s two biggest airports, Heathrow and Gatwick. It has created a multimillion-dollar headache for the British government, and further illustrates the cost of underinvestment in public goods and of relying on quick fixes for long-term needs.

“The problem with these panels is not so much the material itself. It’s the fact that they’ve been used well beyond their expiry date,” says Juan Sagaseta, a reader in structural robustness at the University of Surrey. “Unfortunately, spending on new buildings and opening new schools or hospitals is often viewed in our society as more glamorous than spending on maintaining the old ones.”

The issues around RAAC were first investigated in the 1990s by the Building Research Establishment (BRE), an organization initially established as a government agency that now operates as a social enterprise. At the time, the removal of roof panels from some buildings had raised concerns, although there had been no conclusive evidence of immediate safety risks. It wasn’t until 2018 that the Department of Education finally took action, after the ceiling of a primary school in Kent, in Southern England, suddenly collapsed. Fortunately, the incident happened on a Saturday and no one was injured. The school had been rebuilt in 1979 using RAAC after a fire. School authorities were sent questionnaires to try to establish whether or not they had RAAC in their buildings, but, Sagaseta says, they (understandably) often didn’t have the expertise or resources to identify the material. Finally, in the fall of 2022, the Department of Education sent out professional surveyors to classify RAAC constructions as “critical” or “noncritical.”

The sudden decision to close schools this summer was triggered by three cases of RAAC panels that were considered noncritical but later failed. The first incident involved a commercial building, the second a school in a different country, and the third an English school in late August. The 150 or so institutions now known to be at greatest risk represent a tiny fraction of the 22,000 state-owned schools, colleges, and nurseries in England.

But these instances are just the tip of the iceberg. Any building constructed cheaply and quickly in the extensive period after World War II is a cause for concern—including court buildings, prisons, supermarkets, and warehouses. As part of a routine investigation, RAAC was also discovered within the Houses of Parliament, which is already in dire need of major renovation.

Chris Goodier, a professor of construction engineering and materials who has been studying RAAC for several years, says that there are hundreds of thousands of RAAC panels spread across various public and private buildings across the UK, which require immediate assessment. “The great majority will be fine and safe. Those that are not safe should be replaced or strengthened.”

For pupils, students, and their parents, the timing of the school closures just before the new term was incredibly disruptive. Some now have to learn remotely, while others have lessons in temporary rooms. The government has said it “will spend whatever it takes to keep children safe,” but it’s not clear how much that would be. Some estimates have put the cost of fixing the problem in the hundreds of millions of dollars.

But for the Conservative Party, which is well behind in the polls, it’s not just about the crumbling concrete crisis becoming more costly as it spreads to other public sectors. How the party deals with the crisis could also be crucial as the election year draws ever closer. Experts have been clear that this crisis is in many ways the product of decisions made by the government. Since taking power in 2010, the Conservative Party has cut the budgets for public services, including for the maintenance of public buildings, first pursuing “austerity measures” to cut the national debt in the wake of the global financial crisis and then pushing a small-state approach to government.

Alice Moncaster, professor of sustainable construction at the University of the West of England Bristol, says that the root of the RAAC problem isn’t the material’s fundamental design. “It was just one of many postwar innovations to get countries up and running again as cheaply and quickly as possible,” she says. Instead, it was politics that got the UK to this point.

"It is a direct cause of lack of maintenance and replacement of public buildings, many of which are well beyond their design life,” Moncaster says. “And this comes from the ‘small state’ approach that the Conservative Party in the UK have been pushing since 2010.”

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