Prefabricated composite heat activated waterproofing membrane composed of distilled bitumen and special polymers which provide thermal adhesive properties to the lower face waterproofing mass. The upper face waterproofing mass promotes heat transmission to the lower face. The thermal activated waterproofing mass allows the membrane to be positioned and applied without the use of open flame and is particularly indicated for those surfaces which are heat sensitive. PROTETTO has woven non woven single strand composite polyester reinforcement, with high mechanical characteristics. The lower face is backed by a special release film which must be removed during application. The P version has a polypropylene mat upper face finish. The PA version upper face of the membrane is self-protected with brun bourgogne colored mineral slates, which reduce heat absorption improving durability, and has a 10 cm side selvedge and 15 cm head selvedge to promote the adhesion between the sheets.