Our surveyors are able to survey for and comment of Reinforced Autoclaved Aerated Concrete including risk assessing condition.
Autoclaved Aerated Concrete (AAC) is different from normal dense concrete. It has no coarse aggregate, and is made in factories using fine aggregate, chemicals to create gas bubbles, and heat to cure the compound. It is relatively weak with a low capacity for developing bond with embedded reinforcement.
The AAC is then reinforced (RAAC) by adding a wire mesh, protection against corrosion provided by a bituminous or a cement latex coating into the formwork and the liquid AAC mix, forming structural units, known as panels or planks.
The surveyor is guided by the fact that RAAC panels were used for the construction of large flat roofs in the 1960-80s, and therefore buildings (or extensions) pre-dating or post-dating this period are unlikely to be affected. All roofs/ceilings reasonably accessible are assessed, visually or where practicable physically. The purpose is to enable the Duty Holder to develop a central register of buildings with RAAC roof panels and inform a risk assessment aimed toward a continued safe occupation on the premises.
For the avoidance of doubt, if the presence of RAAC roof panels (planks) is suspected or confirmed, a further structural inspection/assessment should be arranged. The Department of Education guidance deem this the responsibility of the building owner.