Abstract: A panel assembly for use as a combination drainage and insulation member, primarily on the exterior surface of subterranean walls. The assembly has an insulating board with channels on one side of the board. A fabric which is pervious to water and impervious to soil particles, and has a high modulus, is attached to the channeled side of the board. The resulting board is highly effective to collect water and channel it downwardly toward a drainage pipe which may be part of the drainage system, and which usually conveys the water away from the wall. Improved methods of providing subterranean insulation and drainage are also disclosed.