Schools have been closing because of the risk of collapse from crumbling concrete. These schools were built using reinforced autoclaved aerated concrete or Raac, which is lighter, but less durable than normal concrete, with an average lifespan of about 30 years. The government has urged over 150 schools built with Raac to close until they can be deemed safe through, for example, the implementation of ceiling supports to prevent them from collapsing
