Shipping is free, and the house will show up at your address on a flatbed truck. When you’re buying laundry detergent or toilet paper at Walmart.com, you can also buy a tiny house.One option, a 19-by-20-foot “expandable prefab house,” comes with a steel frame structure that unfolds from the size of a shipping container to create a basic studio cottage with built-in windows, insulated walls, and an insulated roof.