Whether the element is open or closed at the top is determined by the area of application. If, for example, the element is to be filled with fill on site as a storey ceiling or roof terrace (LIGNO Rippe Q3-x), its cavities are open at the top (feature _r0). To guide pipes at the top of the element, a cross grid (_r25, _r50) can be added to some superstructures. For roof superstructures, there is usually a flat closed finish _rg0 (LIGNO Block Q-x, LIGNO Block Q3-x or corresponding versions of LIGNO Akustik klassik).