This European Standard specifies a basic framework to be used to measure the moisture content, or the water content, in materials of the built cultural heritage, i.e. masonry and wood. This European Standard gives operative specifications and clarifies how the various methods respond to the peculiarities met in the field of cultural heritage to prevent instrument misuse, reduce uncertainties and avoid reading misinterpretation. A further aim is to inform and assist users in the choice of the most appropriate method to obtain a reliable measurement even in the case of materials that have undergone weathering, salt migration, pest attack, or other typical transformations over time.