External thermal insulation composite systems described herein include a concrete or masonry wall and a multilayer thermal insulation board disposed on the concrete or masonry wall. The multilayer thermal insulation board includes at least one closed cell foam layer comprising polyurethane and polyisocyanurate having an open cell volume of less than 20% by volume according to ASTM D 6226 and at least one open cell foam layer comprising polyurethane and polyisocyanurate having an open cell volume of greater than 80% by volume according to ASTM D 6226.