Decay of wooden commodities – Moisture risk analysis, service life prediction and performance assessment in the field

Abstract

One key issue in wood construction is durability. Constant wetting and suitable temperatures for fungal growth promote the risk of decay and thus a decrease in structural stability and performance. Hence, performance-based prediction models seem to be reasonable to predict the in-service performance of wooden structures in different outdoor exposure situations. Within this study continuous wood moisture content (MC) and temperature measurements were conducted on five different test objects. Four test set-ups were installed at a test site in Hannover, Germany. A fifth set-up was exposed in Ås, Norway. Data-sets were applied to a dose–response performance model considering wood MC and temperature as key factors for fungal decay. The expected service life (SL) was calculated for different materials and constructions. In addition, the depth and distribution of decay was assessed using a pick test and compared with the calculated SL. Differences regarding the risk of fungal decay for various construction details, exposures and materials were quantified. A wide range of SL estimates was estimated and significant differences were found between the various components, design details and wood species. Furthermore, results from the decay assessments were used to verify the performance model. Recommendations for improvements were provided.

Keywords:

• Decay assessment
• dose–response performance model
• fence post
• moisture monitoring
• service life prediction
• terrace decking

Acknowledgements

Scientific exchange and parts of the experimental work have been carried out in the frame of the European FP7 research project “PerformWOOD”.