In-situ measurement of microclimatic conditions and modeling of mechanical properties of timber structures – A case study on new church on Ruhnu Island, Estonia

Abstract

There are many factors which affect durability of wood in the existing timber structures. One of the most important factors affecting durability is biological, especially the wood-rotting fungi and wood-boring insects. This paper gives an overview about fieldworks on Ruhnu Island and investigations on damages caused by house longhorn beetle and common furniture beetle in the church built in 1912 AD, respectively. Since the church is architectural heritage, only non-destructive methods were used to determine residual cross-sections of existing timber structures. The activity and distribution of beetles were connected with indoor microclimate measurements that were conducted in different locations inside the church. No relations between house longhorn beetle and common furniture beetle spreading in forest and timber elements were found. A thorough renovation and pest control treatment were set based on the results of this investigation. The living conditions and nutrition habits of common furniture beetle and house longhorn beetle were confirmed, and correlation between the mentioned beetles living in forest and in buildings is small. In spite of intensively damaged church's steeple, the strength and stability calculations showed only the need for minor reinforcement of load-bearing timber structures.