The Ytong filling block made of lightweight concrete (aerated concrete), weighing about 550 kg/m³, is placed between the beams and serves as a walking platform. After the reinforcement is laid and a thin layer of plaster is applied, it becomes an integral part of the final construction. In the system, such an individual block can withstand a load of up to 1 ton. With cross and longitudinal cuts, the block dimensions can be easily adapted to smaller spaces between the beams, as well as to different shapes. It has an A1 fire reaction class.