A new type of slab has been developed by the researchers at ETH Zurich. It is just 20 mm thick at its thinnest point, decoratively ribbed and not even half as heavy as a conventional concrete ceiling. Smart Slab is one of the core elements of the residential unit DFAB House at Empa’s and Eawag’s research and innovation platform NEST in Dübendorf. The 80 m2, 15 tonne ceiling consists of eleven concrete segments and connects the lower floor with the two-storey timber volume above. 3D concrete printing is currently experiencing a boom in architecture, and entire houses have already been printed layer by layer. However, for the Smart Slab project, the researchers did not produce the building components themselves with 3D printing but rather the formwork.