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Reinforced autoclaved aerated concrete (RAAC) — why school closures are just the tip of the iceberg?

We examine what was known of those risks and we also consider the implications for other public buildings.

On 31 August 2023, the Government announced that 104 schools must at the start of a new term exclude staff and pupils from buildings which contain RAAC, given the likelihood of a school building collapse — now assessed as “very likely and critical”. This has led to charges that the Government has been asleep at the wheel given its knowledge of the risks.

In this article, we examine what was known of those risks and when, and we also consider the implications for other public buildings.

What is RAAC and when was it used in construction?

Reinforced autoclaved aerated concrete is a mixture of concrete, water and limestone. Essentially, it is a lightweight bubble of concrete. It is commonly found in panels — principally but not exclusively on flat roofs, although it was also used in walls and floors. It has a typical lifespan of 30 years.

Its use in construction was predominantly from the 1950s to the 1980s. The risk of an RAAC collapse is heightened when supports are of insufficient size or steel reinforcement is in the wrong place.

Why is RAAC relevant to schools?

The post-war construction boom saw almost 15,000 schools built between the 1940s and 1980s. Prior to 31 August 2023 announcement, 52 schools already had “safety mitigation measures” in place against RAAC with the additional 104 schools now making a total of 156 schools affected. Given the total number of schools built during this period, it appears inevitable that further investigation will see significantly higher numbers of schools closed in part or in full. It is understood that the Department for Education in May this year estimated that RAAC was present in 572 of the 6,300 schools it had already inspected.

Schools, still dealing with the aftermath of the Covid-19 pandemic amidst declining pupil behaviour and attendance, perhaps understandably view the prospect of closures with a mixture of anger and dismay and as a further barrier to raising standards of educational attainment. It will perhaps add insult to injury to point out that the Government in its written guidance to schools affected by RAAC will (at the time of writing) not cover the financial cost of any emergency temporary accommodation – costs must be met through the existing school budget.

Timeline of warnings on RAAC

2018 — Ceiling containing RAAC panels collapses at a primary school in Kent (over a weekend).

2019 — Standing Committee on Structural Safety highlights the “significant risk” of failure of RAAC.

2022 — Office of Government Property issues a briefing notice which states:
“RAAC is now life-expired and liable to collapse”.

2022/2023 — ITV News Freedom of Information request identifies 68 schools containing “life-expired

16.03.23 — The Guardian — “Union raises concern over funds for school building
repairs in England” references as “critical-very likely risk of buildings collapsing”.

16.08.23 — HSE issues advice on its website:
“RAAC is now life-expired. It is liable to collapse with little or no notice”.

31.08.23 — Government announcement.

Risk in schools is not confined to RAAC

Whilst RAAC may now present as the most pressing, it is not the only issue of concern with an aged estate of school buildings.

The Department for Education’s own estimate places the cost of repairs and remedial work required at £11.4 billion, with capital spending on England’s state schools estate falling by 50% in real terms between 2011 and 2022 (The Guardian, 16 March 2023).

Additionally, the issue of asbestos contained within the fabric of school buildings (in the same post-war construction boom) is the subject of an ongoing Sunday Times campaign to force the removal of all asbestos in public buildings by 2040.

Statisticians have already identified an elevated number of mesothelioma cases — the fatal cancer largely attributable to past asbestos exposure amongst teaching staff employed between the 1950s and 1970s.

The tip of the iceberg?

The presence of RAAC is not merely confined to schools. A separate survey in 2022 revealed 250 NHS buildings in Scotland alone had “potentially” been built with RAAC. It is understood that the Government has now commissioned a survey of NHS buildings to identify the presence of RAAC which is likely to take eight months to complete. We expect overall numbers of confirmed “RAAC presence” to rise substantially over the coming weeks and months.


Precisely why the Government has chosen to issue guidance literally days before the start of a new term appears, to us, opaque. The Education Minister, when challenged, referred simply to a “couple of(unspecified) incidents over the summer”. Both the content and timing of the announcement have been described by the teaching unions as “absolutely disgraceful” and “a sign of gross incompetence”.

Given the timeline of warnings, it is difficult to disagree with those assessments. We expect that disclosure in the coming months will provide a sobering picture of the state of many public buildings. We will report any further developments of note in future articles.

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