The work investigates the influence of a treatment of European beech with curable epoxidized vegetable oils on the wood properties in order to improve them for use as construction elements (such as window frames, exterior doors, façade claddings) or for outdoor applications. Following the political demands for enhancing the use of domestic resources and the forest conversion in Germany for growing more hardwood, it seems useful to upgrade the properties of European beech wood, which is not durable according to EN 350 (2016). Load-bearing components or components exposed to weathering made of untreated beech wood are not permitted. The IHD has therefore developed a tempering process for beech wood, based on the use of radiation-curing epoxidized vegetable oils. By optimizing the formulation, it was possible to generate variants that guarantee optimum curing with a low γ-radiation dose to ensure a significant improvement in the material properties compared to natural beech wood. At the same time the tendency to embrittlement was reduced. Although this type of tempering is not a wood modification in the narrower sense, i.e. no direct modification of the wood cell wall is achieved, material properties are achieved that allow the use in window and door constructions and can compete with already approved modified woods such as TMT or Kebony.