Exterior sheathing panel with integrated air/water barrier membrane

A method of manufacturing an exterior sheathing panel with an integrated air and water barrier membrane, the method comprising the following steps:

• coating a cementitious panel comprising a cover sheet, wherein the cover sheet is a fibrous mat with an exterior facing surface on at least the exterior facing surface with an integrated air and water barrier membrane formulated with 30 to 70% by weight of a polymeric binder comprising a polyacrylate, polyurethane, silicone emulsion, polystyrene, styrene acrylic copolymer or any combination thereof;
• 20 to 50% by weight of calcium carbonate;
• 0.1 to 5% by weight of a wetting and leveling agent;
• and 0.1 to 5% by weight of a cross linker;
• and
• conditioning the coated cementitious panel in an oven, wherein the coated cementitious panel is exposed to at least two different temperature zones, a first temperature zone and a second temperature zone, wherein the first temperature zone has a temperature lower than the second temperature zone.