A waterproof, vapor-permeable and air-permeable sheet material. The sheet material includes a waterproof microporous polymer substrate and a microporous thermoplastic coating layer attached to the polymer substrate. The thermoplastic coating layer is vapor-permeable and air-permeable. The thermoplastic coating layer is at least partially interpenetrated into pores of the polymer substrate forming an interface that prevents passage of water droplets, while permitting passage of water vapor and air, when a chemical is present on the sheet material that would otherwise cause the polymer substrate to permit passage of water droplets. The interface is resistant to chemical interference with at least the waterproof property of the sheet material.