Steel-reinforced concrete construction units have to be made in certain minimum thicknesses, as the concrete cover must meet the requirements of DIN 1045-1. In dry interior areas this is 20 mm including tolerances, whereas for external ele-ments it must be 40 mm, while in the case of ele- ments that come into contact with chloride the minimum is 55 mm. For this reason, steel is not a suitable reinforcement material for very thin structural elements. However reinforcement using plastic, which does not corrode, has worked well.