Any way for terrain tools to go right up to walls?

Sorry to me to-post, do you mind explaining how you managed to get the room above ground and the terrain flush? I have built a whole house already and really want to be able to do the terrain as it needs to be. 

@nottovvy Welllll... Terrain height tools are my friend and nemesis. Terrain height can be super easy, extremely fidgety, or somewhere in-between, depending on your goals, lot, and the stage of building that you are currently at. Hopefully this info will be of some use to you in your situation:

• Use the"Raise Terrain" / "Lower Terrain" tools to raise or lower the terrain.
  Note: With this tool and the other terrain tools, you can adjust the shape, size, speed, and softness of the brush/raising process in the slider settings:
  
  
  
• A handy thing I usually follow up with after raising the terrain is to follow with the "Smooth Terrain" tool:
  
• The "Flatten Terrain" tool is handy  if you want to flatten an area of the raised/lowered terrain to a specific height. (the height will be where you place the white square in the center of the tool.):
  

Edit: Please note that in the case of what I mentioned above the home is on a foundation already. Does your home have a foundation? If the above is not what you meant, and if it doesn't help to read through the posts on this thread and to watch the video linked to in the solution (post #21), can you add a post with a screenshot and clarify what is different in your lot from the above and from the information in this thread?