The purpose of the master thesis will be to investigate different techniques that are able to give an estimation of the bearing capacity of structural elements made of timber. The problem with timber structures is the interaction between all the different contributing factors with regard to its strength. Timber is a very complex material and it is natural which makes it difficult to control its properties and a suitable method must be used in order to quantify them. Non-destructive techniques are the most appropriate for this purpose. Unfortunately correct interpretation of non-destructive techniques is not yet at its peak. Here a focus will be made on ultrasound passing through the material. Acoustic emission will also briefly be discussed. The parameters obtained with these techniques will be compared with well-known parameters coming from a four bending test. In the last part some in situ measurements will be discussed.