This paper deals with a model allowing to calculate and describe, in a universal way, the sorption isotherms in wood material used in the moisture content measurement and the simulation of mass transfers. The originality of the presented tool lies in a thermodynamic approach explained in a few parameters model , grouped by species families, via the notion of normalized isotherms. It is also adapted to non-isothermal environments thanks to the application of Le Chatelier's principle. Finally, the model integrates partial isotherms, which makes it possible to use it not only to characterize the material sorption properties, but also to integrate it in heat transfer algorithms or in the implementation of moisture monitoring of timber structures under uncontrolled environments.