Waterproof breathable membrane is three layers thermal lamination. Polypropylene (PP) non-woven fabric layer is on the top and bottom for protection and reinforcement, and micro-porous polyethylene (PE) film is in the middle as breathable membrane. The membranes are commonly used as waterproof underlay beneath the roof covering, which is impervious to rains or snows, meanwhile they are vapor permeable and allow the moisture escape from the roof structure to avoid mold and rot of fiberglass or insulation or wood structure, and keeping excellent R-value.