Studies on the material resistance and moisture dynamics of wood after artificial and natural weathering

Wood is one of the most important building materials. During the service life of wood and derived materials, various degradation factors affect performance. To assess how weathering influenced the material resistance and moisture dynamics of wood, 11 different materials were exposed to natural weathering for 9, 18 and 27 months or artificial accelerated weathering. Afterwards, the moisture performance of wood was determined in line with the Meyer-Veltrup procedure. Weathered samples were also exposed to the brown-rot fungus Gloeophyllum trabeum for 16 weeks. Respective materials were classified into durability classes according to EN 350, and relative resistance dose (D-rd( rel)) was calculated. Weathering resulted in leaching of biologically active extractives, changed surface morphology and increased permeability. All these changes were reflected in decreased relative resistance dose for all tested materials. The largest deceases were determined for thermally modified wood, Scots pine, European larch and sweet chestnut heartwood.