Composite membrane for building applications

A roofing system, comprising:

• a steep sloped roof comprising a substrate;
• and
• a roofing composite membrane installed on the substrate,
• wherein the roofing composite membrane
• is in the form of a sheet,
• has a width of at least 2 feet,
• is not a shingle, and
• is not covered by a shingle,
• the roofing composite membrane comprising:
• a coating layer comprising:
• at least one inorganic additive, and
• a first thermoplastic polyolefin comprising polypropylene, wherein the first thermoplastic polyolefin has a melt flow rate between 0.5 grams per 10 minutes and 12 grams per 10 minutes,
• wherein the coating layer comprises a top surface and a bottom surface opposite the top surface,
• wherein the top surface of the coating layer forms a top surface of the roofing system;
• and
• a base layer comprising a second thermoplastic polyolefin,
• wherein the base layer comprise a top surface and a bottom surface opposite the top surface,
• wherein the bottom surface of the coating layer at least partially covers the top surface of the base layer;
• and
• an adhesive layer,
• wherein the adhesive layer at least partially covers the bottom surface of the base layer.