Decay resistance of thermally modified Scots pine after 6 years' exposure above ground

In the present study the performance of boards treated by ThermoWoodr process were studied above ground and the results given are based on a "modified" horizontal double- layer test. The base layer of boards was in direct contact with ground and the conditions were much harder than in the standard method. After six years' exposure clear differences were found between untreated Scots pine and treated ones. In all cases thermal modification improved the performance. The greatest differences were discovered in boards located in base and lower boards of the double layer test. The best performed thermally modified pine heartwood, where only very little decay was found in base layer boards laying against the ground. Other layers were not attacked. The same trend was detected with Scots pine sapwood, but already some decay was also present in lower and top layer of boards. The smallest differences between modified and unmodified were found in upper layer of boards, which mainly suffered from blue stain and cracking. Also in this occasion pine heartwood performed better than sapwood boards. In addition, measured moisture content figures were in good correlation with found decay rates.