The wood, composed of alternate earlywood and latewood lamellae, forms a statically determinate system with two redundants. The redundant forces are the shearing forces rising at the edge of the boundary between earlywood and latewood in the longitudinal and the tangential directions of wood. By determining the redundant forces according to the theory of statically indeterminate systems, we know the state of stress and the state of deformation of the wood element and thus can determine its shrinkage and stresses in the longitudinal, tangential and radial directions.