Prefabricated external wall elements for CLT systems

This is a first pre-study to how building with cross-laminated timber (CLT) as a frame system in buildings could be made more efficient using prefabricated exterior wall elements as frame completion for CLT buildings. In carrying out this study, CLT building in Sweden as a rule involves an efficient frame erection of the CLT elements, but with a relatively slow phase to assemble the exterior frame completion. External frame completion of CLT buildings is usually carried out on construction scaffolding, where the layers of insulation and surface layer are built up on site. Prefabrication of the outer layers of the CLT frame that is lifted into place has the potential to save a lot of labor time and thus costs. The report presents requirements and practical aspects that must be taken into account in order for prefabricated exterior wall elements to be feasible in terms of requirements and in practice. The purpose of the report has also been to give tips, inspiration and ideas to consider when producing prefabricated exterior wall elements. In the study, an example solution has been developed with the aim of being wood based to as high degree as possible. The result shows that with relatively simple means it is possible to build a prefabricated wall element that meets established requirements. It is desirable that the outer wall elements are hung in place with the minimum possible finishing work on the facade. When it comes to the division of external wall elements, it is practical to follow a similar division and measurements as for the CLT boards to facilitate handling, assembly and lifting. It should be avoided to have sockets (window panes, door holes and the like) that are broken in its interface between the external wall elements to facilitate uniformity in the dimensioning of the elements. The study shows that it is realistic to create prefabricated exterior wall elements for CLT frames.