Permeability of wood for hygroscopic moisture is an essential property for its use in ordinary 
and industrial applications. The property is highly dependent on wood moisture content. This 
statement was however, not yet sufficiently proved over the whole hygroscopic range (0-97 % 
relative humidity). Also, no general function for this relation was firmly proposed. The goal of 
this project is to investigate if the moisture content is the dominant macroscopic property 
controlling the moisture permeability of spruce wood over the whole hygroscopic range and in 
its three anatomical directions. At first will be finished a long-term measurement of permeability 
of wood in adsorption and desorption regimes and performed supplementary measurements. 
Based on careful numerical analysis will be presented relation of the permeability to moisture 
content and proposed forms of mathematical functions. Finally, physical mechanisms controlling 
the moisture transport will be analysed and compared with other theories. Results may present 
an important step forward in understanding of the transport in wood