Hot Bitumen Waterproofing Bitumen, also known as asphalt, is a sticky, black and highly viscous liquid or semi-solid form of petroleum. Thanks to its waterproofing qualities, it is widely used in construction. Bituminous membranes are perfect for waterproofing roofs, basements, below-ground structures, bridges and other structures. Bituminous waterproofing systems are designed to protect residential and commercial buildings. These systems are sometimes used to construct roofs, in the form of roofing felt or roll roofing products.