I'm using V10, and have a 2 storey house. With the exterior walls selected, I used the ceiling/floor button in the properties bar to create a ceiling. It's 1' thick at 9' elevation. Then, while working on the 2nd floor, I created a cutout at the correct elevation. But it doesn't create a hole in the floor. If I make it really thick. and mess with the elevation, then I can create a 'box' that goes between the 1st and 2nd floor, but I can't get any transparency between the floors in live view. On a side note, is there a difference between a first floor ceiling and a 2nd floor floor? Do I need both?

Hi markarm,

You mention "I created a cutout at the correct elevation" , but we must discuss about "the correct elevation".
1 - The ceiling elevation is the bottom face of the ceiling. This means that if you the floor of the second floor is @ 108", and your 1st floor has a ceiling of 12", the ceiling elevation will be 96" and the settings of the cutout will be the same: elevation at 96"and thickness= 12"

2 - If you used Autofloor in the 1st floor, the ceiling elevation will be the walls' height + the Autofloor thickness

3 - If you used a floor in the upper floor, you must consider this thickness in the floor cut

Regarding your question "is there a difference between a first floor ceiling and a 2nd floor floor? Do I need both?". It depends. If you used Autofloor for the whole plan (one piece covers all the plan), notice that you will not be able to set different materials for each room. In this case, you can use a manual floor to fit each room, however, this solution will change the results of the Estimator, if you are going to use it
You can set a 2D shape created in the 3D workshop to set the floor, but this is not a nice solution

Patricia