House with garage under 1st Floor

[anditx14]

I am new to CA and wanted know if anyone knows how to set up the following. I am trying to create a house that will sit upon a hill. The house has a first floor and a basement that would contain the garage and other rooms. I am trying to make the garage downstairs however the garage and other rooms in the basement do not necessarily sit all under the 1st floor of the house. Parts of the garage/rooms would actually be under ground or under a deck. I keep seeing no ceiling to the garage and the terrain is going through the garage wall. When I started the house, I created the 1st floor, then added a basement. I then manipulated the basement so that it start to show the garage and the other rooms down there. See file attachment to see what I mean. Does anyone have any ideas on how I can correct this?