This standard specifies two alternative methods for determining hygroscopic sorption properties of porous building materials and products: a) using desiccators and weighing cups (desiccator method); b) using a climatic chamber (climatic chamber method). The desiccator method is the reference method. The standard does not specify the method for sampling. The methods specified in this standard can be used to determine the moisture content of a sample in equilibrium with air at a specific temperature and humidity.