When I try to make a two-storey house, the second floors's floor is invisible (in 3D view) .
I know that there are two buttons for each floor (on the top of the compass) in order to see how the proccess of each floor is going. When I press the 'Level 0' button, the first floor only is apperaed in 3D view. Although, when I press the 'Level 1' button, the two floors are appeared at the same time (in 3D view), with the first floor on the botom and the second floor on the top.
Pressing the 'Level 1' buttom, the two floors are appeared without something between them in order to make clear that the two floors are seperated from each other. Also, the furnitures that are placed on the second floor are illustrated like they're on the air. I think that the Sweet Home 3D must have a layer/floor or something between the two storeys in order to seperate them better.
picture of a two-storey house pressin the 'Level 1' button :
