ETH zürich crafts ultra-thin curved concrete roof

researchers from ETH zürich have successfully built a prototype of an ultra-thin, curved concrete roof using innovative digital design and fabrication methods. the tested novel formwork system will be used in an actual construction project for the first time next year.

block’s team built the prototype over the course of six months
image © block research group, ETH zürich / michael lyrenmann

a prototype for an ultra-thin, sinuous concrete roof using innovative design and fabrication methods has been designed and built by researchers from ETH zürich. the shell is part of a roof-top apartment unit called ‘hilo’ that is planned to be built next year on the nest, the living lab building of EMPA and EAWAG in dübendorf, switzerland. the penthouse will provide living and work space for guest faculty of EMPA. researchers intend to put the new lightweight construction to the test and combine it with intelligent and adaptive building systems.

tried and tested to scale
image © block research group, ETH zürich / naida iljazovic

the self-supporting, doubly curved shell roof is comprised of multiple layers: the heating and cooling coils and the insulation are installed over the inner concrete layer. a second, exterior layer of the concrete sandwich structure encloses the roof, onto which thin-film photovoltaic cells are installed. eventually, thanks to the technology and an adaptive solar façade, the team expect the residential unit to generate more energy than it consumes.

algorithms for controlling the shape
image © block research group, ETH zürich / naida iljazovic 

the cable net is designed to take on the desired shape under the weight of the wet concrete, thanks to a calculation method developed by the group and their collaborators in the swiss national centre of competence (NCCR) in digital fabrication. the algorithms ensure that the forces are distributed correctly between the individual steel cables and the roof assumes the intended shape precisely. the cable net weighs 500 kg and the textile 300 kg; thus, with a total of only 800 kg of material, the 20 tons of wet concrete are supported. the construction of the roof would be inconceivable without state-of-the-art computation and fabrication techniques, but the project also heavily relied on the expertise and experience of several craftspeople.