This European Standard describes the reference method, used for type testing and in case of dispute, for determining the water suction height of an aggregate in direct contact with a free water surface. For other purposes, in particular production control, other methods may be used, provided that an appropriate working relationship with the reference methods has been established. NOTE Capillary water uptake in an aggregate layer under the ground floor may cause moisture problems in the building. If the layer is thicker than the water suction height of the aggregate used, the layer is considered as a capillary barrier.