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