The crisis over the use of aerated concrete in public buildings has taken another twist after an MP claimed a hospital using the substance was so fragile that obese patients could only be treated on the ground floor.

Dame Meg Hillier, chairwoman of the public accounts committee, said the problems that have forced more than 100 schools to shut classrooms over safety fears are just the ‘tip of the iceberg of a failing school estate’.

Schools across the country have been affected, with the closures ordered by the Department for Education after a number of collapses in buildings that used reinforced autoclaved aerated concrete (RAAC) over the summer.

Some parents in Leicester – where schools returned this week – revealed they had been turned away from the school gates after the Department for Education ordered it to close overnight. 

Schools minister Nick Gibb has insisted most schools are safe and urged parents not to worry, telling Times Radio yesterday: ‘Parents can be assured that if they haven’t heard from schools, that it is safe to send their children into school.’

Caroline Evans, headteacher at Parks Primary School in Leicester, stands next to a taped off section inside the school on Friday

Staff move furniture and equipment out of a closed classroom at Willowbrook Mead Primary Academy in Leicester on Friday

Dame Meg Hillier, pictured, says the closure of school classrooms due to the aerated concrete is ‘just the tip of the iceberg’

However, there have been calls for transparency over the the scale of aerated concrete in public buildings, with fears it has been used in hospitals, courts, prisons and even in Parliament.

Dame Meg Hillier said the state of some public buildings was ‘jaw-dropping’ and claimed that a visit from the public accounts committee to two hospitals had left members shocked.

Writing in the Times, the 54-year-old said: ‘In one hospital, staff can carry out roof maintenance only if they and their tools are below a certain weight. 

‘Heavy patients must be treated on the ground floor because the combined weight with equipment is too heavy to be safe. Roof failure is a daily risk.’

The Labour MP condemned the Government for not acting sooner, claiming RAAC was first identified as an issue in school roof collapses in 2018.

Speaking on Times Radio this morning, she said: ‘[You] wonder why it has been left to deteriorate for so long.’

‘In both schools and hospitals, there hasn’t been enough money going into buildings and equipment,’ she told Times Radio.

‘In both schools and hospitals, there hasn’t been enough money going into buildings and equipment.’

She added the cost of working around it  using temporary measures was ‘enormous’.

‘We’re talking millions of pounds to survey a roof in a corridor in order to make sure they know where the problems are… Every time another problem arises, they have to go back and do another survey,’ she said.

She said the costs were ‘eye-watering and wasteful when you think about the problems in the NHS at the moment’.

The Government has said it will rebuild seven hospitals most affected by RAAC by 2030, after reports it is present in 24 hospital buildings in England and potentially as many as 250 NHS buildings in Scotland.

Last month Harrow Crown Court in North West London was shut for the foreseeable future after RAAC was discovered while improvements were being carried out.

And the Ministry of Justice is investigating whether any prisons have been built with RAAC after it found the material in six buildings in the court system. Meanwhile the Ministry of Defence has been examining hundreds of barracks and training facilities.

Opposition parties are demanding information about the scale of RAAC across the public sector estate, with Labour calling for an ‘urgent audit’.

It comes as parents at some schools still don’t know if their children will be starting the new school year in the classroom in two days time.

A total of 104 schools and colleges were told by the Department for Education to partially or fully shut buildings just as pupils prepare to return after the summer holidays.

Though not confirmed, it is estimated that around 24 schools in England have been told to close entirely because of the presence of RAAC, the PA news agency understands, and schools minister Nick Gibb has admitted more could be asked to shut classrooms.

Those unable to open will have to teach pupils online, in temporary buildings, community centre and even empty offices. 

Yesterday furious parents were left ‘frustrated’ and hit out after the closure of their children’s schools less than a week before the term starts.

Thousands of pupils now face a return to Covid-style online lessons on Monday – and ministers admitted that they do not know how many will need to close completely. 

Scaffolding is seen on Friday as repair work continues at Hornsey School for Girls in North London

St Francis Catholic Primary School in Ascot, Berkshire, on Friday where workers have erected temporary classrooms as marquees on the school field due to the presence of RAAC in the roof

Mr Gibb said that a collapse of a beam that had been considered safe over the summer sparked an urgent rethink on whether buildings with the aerated concrete could remain open.

He insisted schools were contacting affected families and told the BBC’s Today programme ‘we will publish a list’, but only once they are in a ‘stable place’.

Former home secretary Dame Priti Patel added further pressure, telling the BBC the closures were ‘deeply concerning’ and would make the start of term ‘quite difficult’ 

But the problem could be far wider, with other buildings at risk of ‘sudden and catastrophic collapse’ if Raac is not removed, specialists said.

Chris Goodier, professor of construction engineering and materials at Loughborough University, said ‘the scale of problem is much bigger than schools’, covering health, defence, justice and even the private sector.

Matt Byatt, president of the Institution of Structural Engineers, said that any high-rise buildings with flat roofs constructed between the late 1960s and early 1990s may contain RAAC.

He said expert bodies had warned Government departments about the dangers of the material in 2018 – adding that ‘everyone was aware’ of the problem.

Mr Byatt said: ‘RAAC has been found in schools, there was a massive thing about it in hospitals and there was a courthouse shut down last week.

‘They are beyond their serviceable life. We (structural engineers) raised the issue several years ago. It is the responsibility of building owners and estate managers to ensure their buildings are safe.

‘The information was out there – everyone including all Government departments were aware of it. Luckily it is being dealt with now. You can’t wait for people to get hurt before making these kinds of decisions. You can have a sudden and catastrophic failure of units.’

A report by the Collaborative Reporting for Safer Structures published in April 2020 urged its members to check as a ‘matter of urgency’ whether their buildings had the material.

Schools minister Nick Gibb attempted to calm worries in a round of interviews on Friday. He told Times Radio: ‘Parents can be assured that if they haven’t heard from schools, that it is safe to send their children into school’

The report said that RAAC was used ‘primarily’ in offices and schools but that it had also been found in a ‘wide range’ of other buildings in both the public and private sector.

It said concerns had been raised about the safety of RAAC roof planks as early as the 1990s and early 2000s.

‘The limited durability of RAAC roofs and other RAAC structures has long been recognised; however recent experience (which includes two roof failures with little or no warning) suggests the problem may be more serious than previously appreciated and that many building owners are not aware that it is present in their property,’ the report said.

Professor Chris Goodier, professor of construction engineering and materials at Loughborough University, said: ‘The scale of problem is much bigger than schools.

‘It also covers much of the building stock in the country. This also includes health, defence, justice, local government, national government, and also a lot of the private sector

‘Most of the towns in the country have old factories and offices and some of those will have RAAC.’

RAAC is a lightweight material used in roof, floor, cladding and wall construction in the UK from the mid-1950s until the 1990s.

Mr Byatt said it is ‘misleading’ to call it concrete as it is far lighter than that term allows.

He said it is better understood as a ‘bubbly, breezeblock’ type material which acts like a ‘sponge’ soaking up moisture when it gets wet.

The extra weight, combined with the fact that RAAC roof planks tend to dip or sag over time, makes them prone to sudden collapse, Mr Byatt said.

‘It was first used because it was lightweight, cheap, and good for insulation but it wasn’t capable of bearing heavy loads,’ he said.

‘The problem is that for a lot of them, the steel reinforcements did not go to the end of the (RAAC) planks, meaning a small section of unreinforced RAAC is taking all the weight.’