Betkal pouring is a roof waterproofing technique based on a special mixture consisting of cement, sand and a foaming agent. The mixture forms a lightweight material with a spongy and soft texture containing large numbers of air bubbles, also known as “foam concrete”. The Betkal is poured as a layer of varying thickness covering the surface of the flat roof and forming a system of slopes, enabling rainwater to flow uninterrupted into the drain openings. Betkal filling may be used indoors as a base for the flooring, substituting for sand/(pea) gravel.       

Application in practice starts with forming the roof slope by stretching strings between the edges of the roof at the desired height towards the drainage outlets. A long hose is then connected to the cement mixer, and the lightweight Betkal mixture is poured while shaping the slope toward the drains. Once poured, the layer is left to fully set for at least a month. In the final stage, waterproofing is applied over the dry Betkal using either bituminous or PVC sheeting.