The corroded and weakened Reinforced Autoclaved Aerated Concrete (RAAC) roofing panels found at the Ontario Science Centre (OSC) which prompted its closure on safety grounds are also a problem in 366 Toronto area schools. The focus is now on the lightweight cementitious panel Domtar product marketed from about 1950 to 1990 called Siporex, which involved … Continue reading RAAC roof panels more like ‘waxed cardboard’: Waterloo professor