The Autofloor makes the difference

If you have a exterior wall with Autofloor= 12" (for example) and you insert a door, the door elevation will be 0", because the door elevation is related with the wall. Same situation with the windows
But if you are going to insert a table on the floor, the object elevation is related with the grass (floor of the Punch world), so the table's elevation will be 12"

Therefore, if your exterior walls have 8'-0", but you are using an Autofloor with 12" (1'), the ceiling elevation should be 9'-0"

Now, the Interior Walls' elevations are related to the "grass", so you should set the elevation at 12"

Always remember 3 things
--> The ceiling elevation is the bottom face of the ceiling. This means that if you the floor of the second floor (for example) is @ 108", and your 1st floor has a ceiling of 12", the ceiling elevation will be 96" and the settings of the cutout (if you have one) will be the same: elevation at 96"and thickness= 12"
--> If you used Autofloor in the 1st floor, the ceiling elevation will be the walls' height + the Autofloor thickness (as described above)
--> To set the objects, walls, etc at the right elevation, you must need to set the ceiling heights. To do this--> Design--> Default Ceiling Heights--> set the exact height of each level. By default, they are 96", this means that (if you don't set your custom heights) Punch will set the second floor at 96" from the grass and the 3rd floor at 192" from the grass

Patricia