SBS/APP modified bitumen waterproofing membrane is made by soaking bitumen or thermoplas ticityelastomer(such as styrene butadiene-SBS), or thermoplastics (such as atactic polypropylene - APP, APAO, APAL) modified bitumen on the surface, then covering double faces with elastomer (SBS) or thermoplastics (APP,  APAO, APAL) modified bitumen, and finally finishing the upward face with fine sands, mineral slates (or grains) or polythene membrane etc, while downward face with fine sands or polythene membrane.