Experimentelle und numerische Untersuchungen des hygrothermischen Verhaltens von Brettsperrholz am Beispiel einer Außenwand

Experimental and numerical investigations of the hygrothermal behaviour of cross laminated timber using the example of an exterior wall – Within the scope of the project “massive_living” in Graz (AT), sensors were installed within an external wall section in a solid wood construction with cross laminated timber and observed over a period of more than two years. Due to the hygroscopic behaviour of wood, the moisture content of the wood adapts to the surrounding climate (equilibrium moisture content). The wood moisture content has a significant influence on all mechanical, physical and chemical properties of wood. Therefore, the knowledge of wood moisture content is of great importance for the realisation of wooden structures. According to öNORM EN 1995-1-1-1:2019 [1], load-bearing timber components are divided into service classes with regard to the surrounding air, which have a significant influence on the verification in the limit states of load-bearing capacity and serviceability. The question now arises as to which values the wood equilibrium moisture content of a building component can assume in the course of several years. The aim of this research project was to gain an understanding of the hygrothermal behaviour of a cross laminated timber wall (CLT wall) and then to compare the measurement data obtained with those from the simulations. The simulation results show a strong influence of the indoor conditions on the wood equilibrium moisture, whereby a good-natured behaviour with regard to moisture buffering can also be observed at high moisture loads. In addition, further measurements showed a dependence of the relative air humidity on the room height, which should be taken into account in hygrothermal calculations (as for example in the area near the ceiling).