Prefabricated waterproofing membrane composed of distilled bitumen and elastomeric polymers (SBS) with fibreglass mesh reinforcement. The upper surface is protected by a dimpled copper / aluminium foil. Self-protection with a metal foil, besides conferring architectural features to the product, protects the membrane from the elements and enables proper reflection of sun rays, thus increasing durability. To enable a perfect sealing of the sheets, the products protected with metal foil are provided with lateral overlap. It can be used in all cases where, in addition to a perfect sealing of the sheet, a particular surface finish for aesthetic needs is required. Coverage with specific aesthetic requirements, in historic or monumental centres.