More than 100 school buildings across Hertfordshire are to be surveyed, amid national concerns about the safety of a type of concrete.

Reinforced autoclaved aerated concrete (or RAAC) is a lightweight material used in the construction of schools and other public buildings, between the 1950s and 1990s.

But there are mounting concerns that, being weaker than traditional concrete, it can be prone to collapse.

And this week the Department for Education said no school or college with confirmed RAAC ‘should remain open without mitigations in place’.

Officials from Hertfordshire County Council suggest that no school in the county will need to close as a result of the directive.

But at the request of the DfE, 120 school buildings in the county – built between 1935 and 1995 – will now be surveyed.

Earlier surveys by the county council – concentrating on schools built between 1959 and 1985 – identified three schools with RAAC that were in need of remedial work.

But, according to the council, that remedial work was completed last year (2022).

Correspondence from the county council, seen by the Watford Observer, states Bushey & Oxhey Infants School was one of the three schools.

“Hertfordshire County Council is not aware of any Hertfordshire schools needing to close as a result of today’s direction from the Department for Education on managing Reinforced Autoclaved Aerated Concrete (RAAC) in schools,” said a spokesperson for the county council.

“Between 2020 and 2021 Hertfordshire County Council carried out surveys of all local authority community and voluntary controlled schools that included buildings constructed between 1959 and 1985 to check for RAAC.

“This identified three schools that needed remediation works, and those works were completed in 2022.

“The DfE have now asked for all schools with buildings constructed between 1935 and 1995 to be surveyed. This survey work, which will cover 120 schools, is now underway.”

Academies and voluntary aided schools will be responsible for their own surveys and any subsequent remedial work.

But council officials say they will work with the DfE ‘to support them as necessary’.

Officials from the Department for Education issued the latest guidance on Thursday (August 31) – just days before the start of the autumn term.

They say they have taken the ‘precautionary and proactive’ step following careful analysis on ‘new cases’.

Nationwide they have contacted 104 educational settings with confirmed RAAC without mitigations in place to ask then to vacate spaces or buildings known to contain the material.

But they say that most of these settings will remain open, because only a small part of each site is affected by RAAC.

“Nothing is more important than making sure children and staff are safe in schools and colleges, which is why we are acting on new evidence about RAAC now, ahead of the start of term,” said Education Secretary Gillian Keegan.

“We must take a cautious approach because that is the right thing to do for both pupils and staff.

“The plan we have set out will minimise the impact on pupil learning and provide schools with the right funding and support they need to put mitigations in place to deal with RAAC.”