The story of ‘The Three Little Pigs’ is hammered into us all from an early age. But its moral lessons obscure its more literal advice about building: skimping on materials is a false economy. It’s a lesson learned too late for schools built with reinforced autoclaved aerated concrete (Raac). Who would’ve predicted that concrete made cheaper by cutting it with air, puffed up like a Malteser, would end up crumbling like one too? It’ll soon prove that the initial cost savings of Raac will be wiped out multiple times over once the risk to life and expensive, disruptive repairs have...