Methods for the monitoring of wood moisture content in taller timber buildings

The moisture content of wood is one of the key elements for the quality assurance during production, erection and service time of timber structures.
“Wood properly protected and controlled is very powerful and durable.”
Therefor continuous monitoring of wood moisture content is a suitable early warning system. The importance of wood moisture in relation to possible damage in timber construction is shown in a study of Frese & Blass (2011), where 50% of all investigated objects show damage or failure due to wood moisture changes or low and high wood moisture contents. Another study by Dietsch & Winter (2018) shows that 30% of these objects are damaged due to seasonal or climate-induced wood moisture changes. Since the distribution of wood moisture is often not constant across the cross-section, internal stresses perpendicular to the grain (moisture-induced stresses, MIS) arise due to the anisotropic moisture-strain behavior. These stresses can easily exceed the characteristic tensile strength perpendicular to the grain and lead to crack development, Möhler & Steck (1980). In curved glulam beams, these stresses can also directly lead to the total loss of load-bearing capacity, as shown in Aicher et al. (1998) or Gustafsson et al. (1998).