Mine is under a roof with no walls. Since we often use it as a guest house I like being able to see out the windows. If I ever get to build walls I plan to put in lots of windows to preserve the view. Also, it will need to be climate controlled or able to vent to keep the air fresh inside. The nice thing about no walls is that it's easier to expand, I have already done that twice. The main thing that I would really like to have now is the ability to dump where it is parked. That would be useful even if we didn't use it as a guest house. Dump stations are hard to find on some of my routes home so I often arrive with at least something in the tanks, plus I generally try clean the coach and rinse the tanks thoroughly after a trip.