The importance of renewable and environmentally acceptable materials in the construction industry is increasing. Wood is one of the most important construction materials and its use in building applications has further expanded in recent decades, mainly due to the development of modern composites, firstly glue lam, OSB (Oriented Strand Board), LVL (Laminated Veneer Lumber) and a considerable breakthrough was later achieved with the development of cross-laminated timber. In order to enable even more extensive and reliable use of wood in outdoor applications, factors affecting a wood’s service life need to be understood. It is well known that fungal degradation of wood is predominantly affected by temperature and wood moisture content. In order to elucidate the influence of these two factors, long-term monitoring of temperature, relative humidity and moisture content at the newly-built Annex of the Department of Wood Science and Technology was carried out. The Annex is designed from CLT composites and glue-lam beams and was finished in December 2015. The results clearly show that microclimatic conditions in the monitored building in the first years of use are far below the limit required for fungal decay or mould growth.