A method of anchoring a joining element to a hollow core board with the aid of mechanical vibration. The hollow core board has a first and second outer layers and a middle layer disposed between the outer layers. An opening, including a mouth, is provided in the hollow core board, the opening penetrating the first outer layer and the middle layer. The joining element includes a wall anchoring portion situated between a proximal end and a distal end thereof. A distal end of the wall anchoring portion is positioned into or onto the mouth with a sealing portion on a proximal end of the wall anchoring portion. The wall anchoring portion is forced through the mouth by applying mechanical vibration and a force parallel to the joining element axis, whereby thermoplastic material of the wall anchoring portion is liquefied and pressed into the first outer layer.