Inside Track

The biggest issues of the month explored | Materials

MATERIALS

Schools shut as cheap materials exceed design lives

More than 150 school buildings close as problem spreads to other public buildings
By Thomas Johnson

Education ministers are facing criticism for failing to refurbish school buildings which have exceeded their design lives and are now structurally unsafe.

In recent weeks more than a hundred schools had to close buildings containing structural elements made of Reinforced Autoclaved Aerated Concrete (Raac) which has been linked to a series of collapses. Many had gone beyond their 30-year design lives.

The school closures followed the collapse of a Raac beam at a school in August.

More than 150 schools have been forced to close buildings containing Raac elements

At least 156 schools have closed buildings and the issue has spread across the public sector, with 34 hospitals now known to contain structural elements made of the material.

Raac is a made from a combination of cement, lime, water and an aeration agent. It speeds up the manufacturing turnaround of precast concrete units. Raac elements contain a high volume of air, making them vulnerable to moisture ingress. They are also known to lose tensile strength in situ. The lifespan of Raac components is estimated to be 30 years.

Of the schools where Raac was found, 52 have already put safety measures in place. The other 104 were unable to open to their full capacity at the start of term in September, pending the introduction of safety measures. Reports suggested at least 24 of those without safety measures in place would have to fully close.

Raac has been identified as an issue for at least five years since an Raac plank failed at a school in Kent. The August collapse has highlighted the issue again. Following this, the Department for Education (DfE) has updated guidance on mitigating Raac’s potential impacts, originally published in 2022.

On 31 August DfE said: “The guidance advises responsible bodies to vacate and restrict access to the spaces with confirmed Raac. Spaces should remain out of use until appropriate mitigations are in place, even where they would have been deemed non-critical previously.”

The Raac reporting system initially put in place by DfE in December 2022 was also updated on 31 August with increased emphasis on the identification of Raac.

Schools have been advised to tell the DfE if they find Raac in their buildings via the DfE Capital Portal.

National Education Union general secretary Daniel Kebede hit out at the government’s handling of the situation.

He said: “We are not confident that the government has a proper plan to address this immediate issue with the urgency it requires, let alone the wider issue of capital funding to ensure school buildings are fit for the future. There are 156 schools with confirmed Raac but how many more where it has not yet been identified?”

Collaborative Reporting for Safer Structures UK (Cross), the anonymous reporting service where engineers can express concerns about unsafe structures, said: “Raac was used in schools, colleges and other building construction from the 1950s until the mid-1990s. It may therefore be found in any school and college building that was either built or modified in this time period.

“Although called concrete, Raac is very different from traditional concrete and, because of the way in which it was made, much weaker.”

Many buildings are now older than their 30 year design lives and there has been an increasing rate of structural failures in recent years as a result.

Harley Haddow civil and structural director Colin Tait said Raac problems have been known to structural engineers for years after a roof collapse at a primary school in Kent in 2018. They have also been reported by NCE.

Tait said: “Cracking to the plank, particularly near its support, and water ingress – whereby it turns the concrete, in essence, to a ‘sponge’ – were felt particularly worrying.

“Hidden behind false ceilings, collapse of these planks could be without warning and devastating.”

The number of Raac-affected schools is expected to grow. In June, a report by public spending watchdog the National Audit Office (NAO) revealed up to 572 schools could have Raac in their buildings.

The material has also been found in at least 37 schools in Scotland. Elsewhere in the UK, the Department for Education in Northern Ireland is urgently checking schools for Raac. There have been no reported cases in Wales.

Arcadis education sector leader Andrew Dutton said the extent of the problem is difficult to quantify due to the difficulties identifying Raac.

“One of the main challenges is that it is not that easy to detect Raac, it is typically in planks forming part of roofs and could be hidden behind suspended ceilings. So normal surveys and condition data do not necessarily confirm if Raac is present.”

Education secretary Gillian Keegan said: “We have been talking to schools about the potential risks of Raac since 2018.

“Recent Raac cases have reduced our confidence in buildings with confirmed Raac, which is why we are taking the precautionary and proactive step to change our approach and have published guidance to that effect.”

The problem is not confined to education buildings. In June, following the NAO’s report, the government expanded its inquiry into the use of Raac to include the whole public sector estate.

Raac planks are believed to be present in at least 34 hospitals in England, while 250 NHS buildings in Scotland are thought to have been built using Raac.

In recent weeks, Harrow Crown Court in north west London was closed after Raac was discovered during building work.

It has also emerged that the material is present in the Palace of Westminster.

Commons levelling up, housing and communities committee chair Clive Betts called for the scope of the Raac investigations to be expanded.

He said: “There’s obviously got to be serious investigations now into hospitals, into other government buildings like courts but also into the housing stock.”

London’s Heathrow and Gatwick airports also recently confirmed the presence of Raac in some of their buildings which are being monitored.