... Membrane downward face with fine sands or polythene membrane SBS Modified Bitumen Waterproof MembraneThe products are made by soaking ... in bitumen,or thermoplas ticiyelastomer (such as styrene butadiene-SBS),or thermoplastics (such as atactic polypropylene-APP,APAO.APAL) ... modifiled biumen,then covering double faces with wlastomer(SBS)or thermoplastics (APP,APAO,APAL)modified bitumen,and last ...