a waterproofing sheet used to waterproof structures above and below grade has a single layer of non - degradable , water impermeable polymeric membrane that has layers of particles of non - hydrated sodium montmorillonite adhering to the membrane in a uniform layered thickness . the layers of particles of sodium montmorillonite spaced from the membrane adhere to each other , with a coating material that is designed to provide the necessary performance for waterproofing under a high water head . the material is in sectioned sheet or roll form and can be easily applied on the job .