RAAC, or reinforced autoclaved aerated concrete, enabled a boom in public building in post-war Britain. It allowed schools, hospitals and other services to be built safely and efficiently, giving working Britons services they had long been excluded from. It, and other manufactured building materials, formed the basis of what are now known as Modern Methods of Construction.

But today it is in the news for all the wrong reasons. In 2018, a RAAC roofing plank collapsed at a school in Kent, damaging equipment and facilities. At the start of the UK school year this autumn, more than a hundred schools were closed, as councils and central government struggled to identify where RAAC had been used and might pose a risk.

In this episode, Trevor Rushton, who literally wrote the book on engineering failures and deleterious materials, explains why RAAC was so useful, what went wrong in its installation and maintenance, and the steps needed to ensure buildings where it has been used remain safe.

Guest

Trevor Rushton, chairman, Watts Group