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In this report, the applicability of the microwave method for measuring moisture in different building materials was investigated. This project included materials, such as brick, sandstone, concrete, sand, gravel, insulation, and wood. At the same time, information was gathered about in situ moisture determination of building materials with a microwave moisture measuring system. The method requires two parallel boreholes in the specimen in which two microwave antennae can be moved. The moisture content in the material can be calculated from the microwave intensity transmitted between the two boreholes. Moisture profiles along the boreholes can be obtained by moving the antennae in steps along the length of the boreholes and taking measurements at each step. The microwave frequencies used in the laboratory measurements ranged from 8 to 16.5 GHz in steps of 0.5 GHz. The moisture content measured by the microwave technique was verified by the moisture content determined by weighing. The results of the microwave measurement were then plotted against the gravimetrically determined moisture content. This report also includes some moisture measurements which were made in the course of an ongoing research project of BAM in two historical buildings in Berlin. These measurements were compared to earlier measurements of the same object. This report also covers the basic theory of microwave transmission measurements of building materials, and includes a description of the measurement principle and equipment and a photo of the setup. 26 refs.