Working in partnership with the manufacturer, the engineers chose Cofrastra composite slabs from ArcelorMittal Construction Austria. This composite slab profile, made from galvanised sheet steel with additional embossed cams, serves as both the formwork for the in-situ concrete and the lower reinforcement layer to absorb the bending moments. The stackable trapezoidal shaped panels are ideal for the inner-city site because they can be easily transported and stored efficiently without taking up unnecessary space. The ribs also reduce the dead weight by up to 15% for the same static height, crucial for the deflection of the slab and resulting in a slim construction with lower loads on the building stock below. Fire protection (REI 90) is achieved by simple bar reinforcement in the ribs (Ø12mm) without additional, time consuming measures, in line with EN1994-1-2.