How to add a dormer to the attic level

[JoAnn]

You can also manually draw these walls just as shown in the 2d pic.

Add wall breaks at each side of the red wall, so that section can be selected.
With a 3D window tiled vertically, select the wall and start changing the roof pitch (shallow pitch) until you can see that the upper part of that roof matches up to the roof ridge perfectly.

When you are completely finished building your roof, turn off 'auto build roof' and raise the shaded 0" floor area to the finished ceiling height it is supposed to be.
The 72" room should have 'ceiling over this room' unchecked in the room dbx box.