MINISTERS have ordered schools to shut down buildings made with aerated concrete as the material is ‘prone to collapse’.

Yesterday, August 31, The Department for Education (DfE) published new guidance regarding reinforced autoclaved aerated concrete (RAAC) in schools.

Without mitigations, affected buildings must not be used until surveys have taken place and suitable systems are installed.

A spokesman for Essex County Council said: “At this stage, we understand that the vast majority of schools in Essex are not affected.

“We have communicated to all Essex schools and have been working quickly to establish schools affected by this new guidance.

“We are working with affected schools to minimise disruption to pupils and families.”

Reinforced autoclaved aerated concrete is a lightweight form of concrete that was used in schools, colleges and other buildings from the 1950s until the mid-1990s.

It is made from a combination of water, cement, lime and an aeration agent.

This is then poured into moulds and subjected to high pressure and heat, a process known as autoclaving, to create a lightweight but strong and porous material.

Records show that as of August 30, there were 156 educational buildings built with RAAC and only 56 of these had mitigations in place.

This mitigations meant engineers had deemed the sites were not at risk due to the areas being closed or reinforced with other materials.

The Essex County Council spokesman added: “We are working with affected schools to minimise disruption to pupils and families.

“Unless informed otherwise by your child’s school, parents should ensure their child attends school as normal when the new term begins.

“Parents and carers of children at affected schools will be communicated to directly by their child's school with information and updates.”

Schools using RAAC are at risk because the material is less dense than traditional concrete.

This means it is prone to collapse over time.

Hockley Primary School was closed in June due to concerns over the presence of the building material.

Winter Gardens Academy in Canvey was also forced to shut.

For more information on government guidelines visit