I did not because as far as I know, I cannot change the wall heights when using Exterior Walls. Please let me know if I'm mistaken but I was not able to find a way to adjust wall heights. When I searched the support documentation, I found an answer that said I needed to use the Straight Half Wall selection to be able to adjust the height. I have used the auto roof building feature but it does not seem to work when I change the wall heights as shown. If the wall heights are the same, it works fine.
The reason is that the rectangular part is a RV garage and that needs to be at least 14 ft tall inside. The square area is the living area so only standard height walls are needed.