Two-component, polyurethane-bituminous liquid waterproofing membrane for waterproofing underground constructions (e.g. foundations), green roofs, non-potable water tanks, irrigation channels, underneath tiles in kitchens, bathrooms, flat roofs etc., under thermal insulation boards on flat roofs etc. Consists of hydrophobic, polyurethane resins (comp. A) and bitumen (comp. B). The membrane formed is waterproof, shows high elasticity and excellent mechanical and chemical resistance.