PLANS are being drawn-up to survey a number of county council owned buildings in Hertfordshire, amid mounting concerns that a type of 'concrete' could be prone to collapse.

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

But it is weaker than traditional concrete, and there are concerns that it could now be prone to collapse.

Last week – following advice from the Department for Education – Hertfordshire County Council said it was to survey up to 100 schools for the material.

And now council officials have told the Local Democracy Reporting Service they are drawing-up plans to survey a number of other county council-owned buildings too.

The county council own a range of buildings that include libraries, day centres, fire stations and offices. It is not know which buildings will be surveyed.

"We have already surveyed all county council-owned buildings built between 1959 and 1989 and did not find any RAAC," said a spokesperson for the county council.

"In light of the updated guidance, we are also now going to survey county council-owned buildings built between 1950 and 1958, and 1990 and 1995.

"However at the moment our main priority is school buildings."

The risk posed by RAAC was highlighted by the Department for Education last week – just days before the start of the autumn term.

Officials said that no school or college known to have RAAC 'should remain open without proper mitigations in place'.

And they extended the range of buildings that would need to be surveyed – to include those built between 1950 and 1958 and 1990 and 1995.

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

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

County council officers have already started to contact council schools that have been earmarked for this latest tranche of surveys.

And on-site surveys by specialist contractors are expected to begin within two weeks.

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

But council officials have already said they will work with the DfE 'to support them as necessary'.

If a survey finds RAAC within a school building that area of the school would need to be closed, until remedial work had been completed.

Initially it was thought a further 120 Hertfordshire schools would need to be surveyed, in line with government guidance.

But it is understood that revised estimates now suggest that will be fewer – at less than 100.

Across the country the Department for Education has contacted more than 100 educational settings with confirmed RAAC without mitigations in place to ask then to vacate spaces or buildings known to contain the material.

However they have said that most of these settings will remain open, because only a small part of each site is affected.