Load-bearing timber modules, which are prefabricated by robots, will be assembled on the top two floors at the DFAB House construction site in Switzerland.
Under the auspices of the National Centre of Competence in Research (NCCR) Digital Fabrication, researchers from ETH Zurich’s Chair of Architecture & Digital Fabrication have developed a new method said to expand the range of possibilities for traditional timber frame construction. It enables the efficient construction and assembly of geometrically complex timber modules, said the researchers.
The robot first takes a timber beam and guides it while it is sawed to size. After an automatic tool change, a second robot drills the required holes for connecting the beams. In the final step, the two robots work together and position the beams in the precise spatial arrangement based on the computer layout. To prevent collisions when positioning the individual timber beams, the researchers have developed an algorithm that constantly recalculates the path of motion for the robots according to the current state of construction. Workers then manually bolt the beams together.
The robots use information from a computer-aided design model to cut and arrange the timber beams. This method was specially developed during the project and uses various input parameters to create a geometry consisting of 487 timber beams in total.
Previous digital techniques have enabled raw materials to be cut to size by machines but in most cases they have still had to be assembled manually to create a frame. This fabrication process has come with many geometric restrictions.
Unlike traditional timber frame construction, Spatial Timber Assemblies can manage without reinforcement plates because the required rigidity and load-bearing result from the geometric structure. Not only does this save material; it also opens up new creative possibilities, according to the researchers.
The Spatial Timber Assemblies project evolved from a close collaboration with Erne AG Holzbau and will be used for the first time in the DFAB House project at the Empa and Eawag NEST research and innovation construction site in Dübendorf. It is also the first large-scale architectural project to use the construction robots developed by ETH Zurich’s new Robotic Fabrication Laboratory.
A total of six spatial, geometrically unique timber modules will be prefabricated in this way for the first time. Lorries will then transport them to the construction site in Dübendorf, where they will be joined to build a two-storey residential unit with more than 100m2 of floor space. The complex geometry of the timber construction will remain visible behind a transparent membrane façade.
The fact that Spatial Timber Assemblies is being used for digital fabrication and also in design and planning offers a major advantage according to Matthias Kohler, professor of architecture and digital fabrication at ETH Zurich. “If any change is made to the project overall, the computer model can be constantly adjusted to meet the new requirements,” he said. “This kind of integrated digital architecture is closing the gap between design, planning and execution,