The present paper deals with the effect of moisture induced stresses (MIS) on the mechanical performance of a glulam beam of Vihantasalmi Bridge in Finland. MIS caused by high moisture gradients in a cross section of the glulam beam are calculated by a hygro-thermal multi-Fickian model for evaluation of moisture content, relative humidity and temperature in wood that is sequentially coupled with an orthotropic-viscoelasticmechanosorptive model for calculation of wood stresses. Both models, already developed in Abaqus FEM code by some of the authors in their previous works, had to be modified for the Nordic climate. The obtained levels of MIS are then compared to the Eurocode 5 design resistances. The study aims at providing suggestions to future developments of Eurocode 5 for the correct evaluation of the influence of moisture content on service life in timber bridge elements.