Need to place a door/window over an area where one floor ends and the next begins

[kathkwilts]

Try adjusting the door's distance from floor (floor to bottom) setting...

So for a stairwell I need to place a door at a landing. The landing is half way between floors as the stairs wind their way to upper floors. If I attempt to place a window or door on that landing, it will go just above or below where the floor structure would be. Even though its really just a wall. How do I make a single wall there instead of two walls divided by a floor?

Notice the doors not at the landing? I'm looking to place a door like the example house shown.