With the 2016 version of EN 350 on determination and classification of biological durability, the scope of materials was extended from natural wood to various wood-based materials. However, there are some deficits to sampling, testing and data evaluation. In order to overcome these deficits, the research project DURATEST had been initiated. Various lab and field tests of the resistance of wood and wood-based materials against wood-destroying fungi were performed, applying the conditions of use classes 3 and 4. The results were statistically analyzed and critically evaluated. In addition, suggestions for improving the test procedure were deduced. The tested wood species and materials represented typical decking materials, i.e. naturally durable, thermally and chemically modified, and impregnated. In all cases, both lab and field tests were carried out and included in the evaluation. This paper reports on the performed lab tests on resistance against soft-rot fungi according to CEN/TS 15083-2:2015. The resulting durability class of thermally modified Scots pine from MOE loss (4v) was one class worse than from mass loss (3v), but all DC of the CMT variants were equal in both parameters. In general, the soft rot tests confirmed the previous observations considering modified timber and pointed out the differences between thermally modified timber (TMT) and chemically modified timber (CMT). By evaluating the soft rot tests, different suggestions to improve the test method were deduced and provided to the responsible standardization committees of CEN/TC 38.