Following EDB’s story in the January/February issue on the DfE’s admission that many school buildings are “very likely” to collapse, an ITV News investigation has identified 68 schools which have have Reinforced Autoclaved Aerated Concrete (RAAC) – a potentially dangerous, lightweight, building material that was predominantly used in roofs between the 1960s and the 1980s. The true number may be higher, as ITV News’ freedom of information request to 5,882 schools in England has revealed 1,466 schools built between the 1960s and the 1980s do not know whether they have RAAC, because they haven’t been checked.ITV News also discovered, via a separate freedom of information request to local authorities, that following the collapse of Singlewell Primary in 2018, 3,717 schools were identified as needing a physical inspection for RAAC, but over half (2,044) still haven't been done. A document published by the Department for Education in December 2022 stated that RAAC panels "increase the risk of structural failure, which can be gradual or sudden with no warning" and that "sudden failure of RAAC panels in roofs, eaves, floors, walls and cladding systems would be dangerous and the consequences serious". RAAC is a lighter form of precast concrete, frequently used in public sector buildings in the UK from the mid-1950s to the mid-1990s.It is less durable than traditional concrete and has a shelf-life estimated to be around 30 years, according to the Standing Committee on Structural Safety. Professor Chris Goodier, a leading expert on RAAC at Lougborough University, commented: "If you keep the RAAC nice and dry then you are fine but if you let water get to it, it can soak it up and if that water gets to the reinforcement inside, it can corrode it and make it rusty. "Post war we had a lot of factories building a lot of buildings very quickly because we needed to. Some of them were rushed and the quality control wasn't as good as it could be or as it would be nowadays," he said. With so many schools not knowing whether or not they have it, the situation has been described as a "ticking time bomb", said ITV News. James Bowen of the National Union of Headteachers commented: “The fact that we know [RAAC] is out there in schools, but the government doesn't know which schools, is absolutely a concern.”