Pre-fabricated waterproofing membrane made of distilled bitumen and elasto-plastic polyolefin polymers (APP) having a woven non woven single strand composite polyester reinforcement, which provide the membrane with very high mechanical characteristics and excellent dimensional stability. The waterproofing compound has a special inorganic and non toxic additive which confer to the product a flame retardant action. The versions PA are self-protected on the upper face with mineral slates which reduce superficial heat absorption improving the durability of the membrane. The self-protected versions have a side selvedge of 10 cm and upon request a head selvedge of 15 cm, to improve adhesion between the sheets.