Coating agent for wooden or plastic surfaces containing 30 to 80% by weight of a polyolefin comprising at least two alkoxysilane groups, 5 to 40% by weight of at least one compound comprising (meth)acryl groups having 1 to 10 radiation-reactive groups, 0.1 to 6% by weight catalysts and initiators, 0 to 50% by weight adjuvants, selected from resins, adhesion promoters, stabilizers, pigments/fillers, softeners, waxes, thermoplastic polymers or water-binding agents, wherein the coating agent is solid at room temperature and can be cross-linked by actinic radiation and by moisture.