Rainboard 2020 is a two ply laminated sheet made up of a grade “D” asphalt kraft building paper on one face and asphalt felt paper on the other face with reinforcing fiberglass scrim in between. The innovative method of its production and lamination results in the creation of a semi-rigid lightweight sheet, which is water-resistant, but permeable to water vapour. Rainboard 2020 meets the requirements of the CAN/CGSB 51.32 and UvU-B-790a standards for breathable sheathing membranes for frame walls. Rainboard 2020 represents a major step forward in outer wall protection. It provides separation and better moisture resistance between the outer wall cladding and the moisture sensitive wall structure for better moisture protection.