UK public buildings feared to be at risk of collapse as concrete crumbles

Ministers have launched a UK government-wide inquiry into the use of crumbling concrete in public buildings following fears that nurseries, offices, shops and leisure facilities are in danger of collapse.

Every Whitehall department has been ordered to assign a civil servant to identify the use of reinforced autoclaved aerated concrete (RAAC) across the £158bn government estate, the Guardian has learned.

Inspectors are thought to have no idea how many out of thousands of government buildings were constructed with RAAC.

The development represents a major expansion of a previous inquiry into the use of the building material that focused mainly on hospitals and schools. Experts have so far identified more than 150 schools where it has potentially been in use, and last week closed a primary in Southend, Essex, because of the safety risk.

RAAC looks like concrete, but it is a lighter form of the material that was used in many one- and two-storey public sector buildings in the UK from the mid-1950s to the mid-90s. Less durable than traditional concrete, it has a shelf-life estimated to be about 30 years and is prone to collapse when wet.

The government first turned its attention to use of the material in schools in 2018 after the roof of a primary school in Kent collapsed 24 hours after signs of structural stress began to appear.

The dramatic expansion of Whitehall’s inquiry emerged in a Local Government Association briefing last week.

“Where it had previously focused on school buildings, central government is now looking to expand RAAC identification and remediation to the wider public estate. The Office of Government Property will be convening a working group in which there will be a designated representative from each government department who is responsible for the identification and remediation of RAAC in buildings owned by that department,” the briefing said.

The government has an extensive property portfolio, which was valued in March 2021 at £158bn and estimated to cost the taxpayer £22bn a year to maintain.

Some of the estate has been sold off the private sector – raising the prospect of expensive and extensive inquiries into the material’s use by private landlords.

The association has issued guidance for councils that says the concrete was “used by some municipal architects primarily in office and schools”. But it says it has been “found in a wide range of buildings, not all of which are still in the public sector”.

“The problem may be more serious than previously appreciated and … many building owners are not aware that it is present in their property,” it said.

An expert has warned that RAAC, which is up to 30 years past its intended shelf life, is also likely to be present in privately owned buildings being used, for example, as shops or leisure facilities. And they could not rule out the possibility it exists in some residential homes.

Matt Byatt, the president of the Institution of Structural Engineers, said RAAC could be present in “office blocks, sports facilities, high street stores and hospitality buildings”. We only know where it is when it has been found. But until someone is looking for it, they wouldn’t know it’s there.”

Byatt believes the general public “need to be aware of this”.

“Councils should be prioritising RAAC as an issue. It is known to have significant defects and way beyond its design life,” he added.

He said that “typically, low-rise structures with flat roofs built between mid-1960s and mid-1990s would be the most likely candidates to contain RAAC”.

It “may be” in higher rise, residential buildings, but “that is not where we have been looking for it so far”.

Byatt explained that RAAC was “the new best thing” when it was first used, because it was “lightweight and ticked a lot of boxes for people who wanted to get buildings up quickly”.

“On the surface, it looks like concrete but when you cut through it you notice how vastly different it is. RAAC is 80% air – like an aero bar. You could probably dig through it with a teaspoon. Cracks, excessive deflection and water ingress are all warning signs that something may be wrong.”

The prevalence of RAAC in hospitals has been widely known about by the government for several years. Last month, ministers announced they were fast-tracking the rebuilding of five hospitals that have “significant amounts” of RAAC, “given the risks they pose to patients and staff”.

The Ministry of Defence is investigating hundreds of military training facilities and barracks for RAAC.

The Department for Education has been surveying schools for more than a year to try to work out how many have RAAC, and how liable this might make them to collapse. At least 150 schools have been found to potentially contain the concrete. But DfE has no idea of the extent of RAAC in other educational settings.

There are growing concerns about RAAC in university and colleges, heightened after the recent closure of three buildings at the University of Aberdeen. Several other colleges are understood to be undertaking surveys to check for RAAC.

In December, the government published guidance for colleges and schools on finding and managing RAAC, and has commissioned three structural engineering firms to investigate any council maintained nursery, college or school where RAAC is suspected.

A government spokesperson said: “Building owners have a responsibility to manage their buildings and ensure they are compliant with relevant legislation, including their duties under health and safety legislation to maintain a safe workplace.”

When it comes to the government’s own estate, the spokesperson said: “Departments are prioritising maintenance and improvement works at those sites which have been identified as containing RAAC.”