RAAC stands for Reinforced Autoclaved Aerated Concrete, a lightweight building material that was commonly used in flat roofing, floors, and walls between the 1950s and 1970s. It is a reinforced version of autoclaved aerated concrete (AAC), which is known for its low density and thermal insulation properties. RAAC is created by adding reinforcement bars to the AAC mixture during the manufacturing process.
In recent years, RAAC has gained attention due to safety concerns. Some older RAAC panels, constructed in the 1950s, 60s, and 70s, have been found to be at risk of collapse if not properly designed, manufactured, installed, and maintained. The Department for Education (DfE) in the UK has been urging schools to check if they contain RAAC and seek expert guidance from qualified Structural Engineers if necessary. A research project into RAAC was commissioned by NHS England in 2022, led by Loughborough University, to further investigate the materials safety issues.
