Walls are by default as high as the floor of the building in which they are inserted. A different value can be specified in the ‘Dimensions’ part of the dialog.
Each wall has a default value for the depth of the ceiling support, that is used when creating ceilings automatically with the exterior contours of the building. The depth of the ceiling support can be manually specified for each wall, or be made dependant on the structure of the wall. With the option for ‘use layer construction’, the ceiling is generated such that it completely rests on the layer of the wall marked as load-bearing. To generate the ceiling support for multi-layered walls, the thickness of all layers up to the top load-bearing layer are added from bottom to top, in the order defined in the ‘Layer construction’ dialog.