Acoustic panels of wood for walls; building panels, not of metal; composite panels of non-metallic materials for use in building; concrete building panels; facing panels of non-metallic materials; interior decorative panels made of non-metallic materials; non-metallic cladding panels; non-metallic panels for use in building; non-metallic panels for use in building; non-metallic panels for use in construction; non-metallic preformed building panels