Abstract: A method of forming a building panel includes embossing dimples into a sheet, where the dimples extend outward from a plane, and expanding a foam core onto the plane and into portions of the dimples. The method may include forming dimples that are convex relative to the plane and the foam core or the sheet having a thin foil having a plastic protective coating. The method may include attaching a cellulosic layer to the foam core opposite the plane. Additionally, flow channels may be formed in the sheet between the dimples, such that expanding the foam core onto the plane substantially fills both the dimples and the flow channels. The method may include embossing concave dimples onto the plane and the foam core, such that expanding the foam core onto the plane substantially fills the concave dimples. The foam core and sheet may bond without adhesives.

Abstract: A panel includes a foam core and a drainage plane attached to one side of the foam core. The drainage plane includes a plurality of dimples extending outward from the foam core and a plurality of flow channels between the dimples. In some configurations of the panel, the foam core extends into the dimples, and may substantially fill the dimples. The drainage plane may be attached to the foam core without being glued or fastened thereto.