To know the minimum moisture threshold (MMThr) in wood allowing for the initiation of the fungal decay by basidiomycetes is relevant both from a theoretical and a practical point of view. The present work summarizes the knowledge about MMThr and presents experimental data obtained by improved laboratory decay tests on Picea abies (Norway spruce) and Fagus sylvatica (European beech) with the fungi Coniophora puteana and Trametes versicolor under different exposure scenarios well suited for simulation in real applications. The three experimental set-ups, in which the pile tests play a pivotal role, differed in terms of external moisture supply and the inoculation strategies. It was confirmed that wood-destroying basidiomycetes are able to degrade wood at high relative humidity without any external source of available liquid water. The method of moistening the wood samples has an effect on the MMThr before initiation of the fungal decay, but different basidiomycetes were able to cause significant decay at moisture contents considerably below the fiber saturation point. © 2017 Walter de Gruyter GmbH, Berlin/Boston 2017.