In at least one embodiment, a microporous membrane having a moderate to high water vapor permeability and high liquid water penetration resistance is disclosed. The microporous membrane may be used in building applications, including as or as part of a building wrap, a rain screen, a roofing underlayment, a flashing, a sound proofing material, or an insulation material. The microporous membrane may include at least one thermoplastic polymer, at least one filler, and at least one processing oil. The microporous membrane may be flat or may have ribs. The microporous membrane may include at least one scrim component. A method for forming the microporous membrane is also disclosed.