I created my own pretend alternate just to practice the different concepts. Take a look at the attached.
I supposed, what if the upper volume was just the middle portion, and what if the chimney was floating within the upper volume. I supposed that the right side would be a length equal to the left side at 18', so that i could do hip roofs all the way around.
The upper volume at the top right collides with an existing window, but if we ignore that, what do you think? Have i grasped the concept okay?