| 主权项 |
1. Building panels, each having a surface layer on a front side, a backing layer on a rear side and an intermediate core, wherein the intermediate core and the surface and the backing layer all comprise wood fibres and thermosetting resins, said building panels are provided with a locking system for vertical and horizontal locking of a first edge of a first building panel to an adjacent second edge of a second building panel, wherein upper parts of the first and the second edge in a locked position together define a vertical plane perpendicular to a horizontal plane, which is parallel to the surface layer, said locking system comprises a tongue and a tongue groove configured to cooperate for vertical locking, and at the first edge a strip provided with a locking element, which is configured to cooperate for horizontal locking with a downwardly open locking groove formed in the second edge,
wherein the backing layer and the intermediate core comprise at least two vertically extending core grooves with an opening towards the rear side, and wherein the area of the backing layer is less than about 90% of the area of the surface layer. |
