Those aren't walls like you normally think of, they are the outside of the cement forms. The walls are poured concrete, not block. The stuff is like styrofoam and they get dirty while the walls are being poured. The guy that had the house earlier also grew weed in that room
I plan on building an accessory building in the next year or 2 also. That one will have high enough ceilings for a lift or 2. I am limited to 720 sqft on that one.