Stairs with sunken rooms

Drigger

So you used to be able to delete the foundation inside the home in buildmode, plop a pad down, and add stairs- boom, sunken room. I hadn't tried this since the terraforming update until today. I did what I had in previous builds but the stairways decide to take a journey to the center of earth (problem). Now I'm stuck with an awesome floorplan and a not so awesome hole. Any ideas?