Dormer style with outside wall the same plane with the house outside wall (pic)

[JoAnn]

Do a full overview & tile vertically, so that you can see how the changes you make affect your house.
Lower the 2nd floor finished ceiling height to about 72" and notice how that creates your 2/3's wall height.
Draw 3 walls against the front wall of the house, to create a small room,(dormer) & give it a finished ceiling height of about 86".
Use the break-wall tool and place a break where each side wall (of the small room) intersects the front house wall.
Select & open that front section of wall (between the 2 breaks) and designate it as a gable roof.
When you've got your entire roof looking exactly the way you want it, you then turn off "auto rebuild roof".
Now you can raise your finished ceiling heights to normal height, and your roof will stay put.

I hope this solution is what you are looking for. Good Luck!