Durability of untreated Norway spruce (Picea abies) exposed outdoors above ground for nine years

Abstract

Abstract Moisture dynamics and durability during weather exposure as affected by origin and production method were studied for nine years on 113 untreated spruce samples. The moisture content was measured on 67 occasions. The weight loss was determined for each sample at the end of the sampling period. The most important factors, affecting both moisture content and weight loss, were origin and drying technique. The samples originating from central Sweden had the best durability, followed by the southern stand, while the northern stand had the lowest durability in terms of weight loss. Air-drying had a negative impact on the performance of samples from all three stands, but to different degrees. Samples from the northern stand were most sensitive to air-drying, in terms of both weight loss and moisture content, followed by the southern stand, while the central stand was least sensitive. Why the samples from the northern stand were more sensitive to air-drying and showed the largest weight losses is unknown; it can only be suggested that the origin of the wood can be of importance for the durability.