The increasing number of wood structure amongst large and potentially public buildings gave a new impulse to the assessment of timber structures. For assessing the state of timber elements, cracks are a key indicator. Therefore, experimental and numerical investigations on not cracked and partly cracked timber members were carried out and analysed. The results show no influence on the stiffness and modulus of elasticity for partly cracked beams. The experimental results were used for the development of analytical and validation the numerical solutions for the assessment of the residual load carrying capacity of cracked timber members. Several models predicting the residual load carrying capacity depending on the crack situation are presented.