174 schools in England have now been confirmed to contain RAAC in their buildings.
The number of state-funded schools, nurseries and colleges affected stood at 147 as of 30 August.
That figure increased by 27 as of 14 September, following weekly surveys of hundreds of education sites in England by officials.
The Department for Education (DfE) will update its findings every fortnight.
Some sites with RAAC confirmed faced delays to the start of term, however many have since introduced mitigating measures.
Still the DfE urges schools and colleges in England to “vacate and restrict access to” spaces with confirmed RAAC in its updated advice.
It has also issued fresh guidance on how to identify RAAC, and how to appoint a building surveyor or structural engineer.
Adding: “Spaces should remain out of use until appropriate mitigations are in place, even where they would have been deemed ‘non-critical’ previously.”
RAAC was a lightweight building material used to construct public buildings like schools and hospitals between the 1950s and mid-1990s.
However, the absence of coarse aggregate – present in ‘traditional’ reinforced concrete – means RAAC has a limited lifespan, after which it deteriorates rapidly, having usually developed air pockets inside.
The Construction Leadership Council (CLC) recently announced a cross-sector response to identify and remedy outmoded building materials in public buildings.
Two industry-led teams will be created to inform and advise the UK Government and building owners on the presence of RAAC across the public sector estate.
Funding for essential works to remove any immediate risk is being made available by the government.
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