Allan,
Your response indicates that I should set 3 sides of the ROOF to 'gable'. My room has only 1 exterior wall and that wall is the short wall where I do NOT want a gable end; therefore, the ceiling rests on 3 interior walls, 1 exterior wall, and the roof structure extends past the 1 exterior wall by 12'. (Columns that will support the eave span are not depicted. In fact, my structure has hip roofs all around; the drawings depict only one room of a much larger structure and the remainder of the structure is omitted. I showed only how the room would sit under PART of the roof. I also showed the allowance for floor joisting on the opposite side of the 22' wall, the ceiling joist level on the 2nd floor and the roof ends where it will peak over the structure. The roof span is 72' on 10' exterior walls with 10/12 pitch. I showed how the roof structure extends past the exterior wall (a rear wall of the structure) to form a porch/lanai.
I managed to insert a ceiling. Because there is a 10' wide opening in the tall (22') wall, I had to figure out how to limit the ceiling to the rectangular area. I did this by drawing a wall on the Ground Floor and giving its 'top/level' attribute a value of zero. I cannot however find any means to set the angle at which a CEILING - not a roof - attaches to a wall at any angle other than 90 degrees.
Regards,
rh
ps
Here is another drawing attempting to clarify the situation. It is just a line drawing to give an idea of the problem. View it as a section or cut-away wherein the point of interest is the red area representing the vaulted ceiling. The near wall shows only the lower, first floor portion with the second floor, sloped near wall omitted to give a view of the vaulted ceiling (red). You can see that there are other portions of the structure. The brick walls indicated where other parts of the structure are attached; the lanai faces an area with exterior structure walls on each side and open at the end. Remember, only part of the structure is depicted.