Our friends at Country Living found an adorable cottage built out of a 1940s-era grain bin outside of New Braunfels, Texas. The galvanized steel of a grain bin is a tough, long-lasting exterior for a tiny home – and in agricultural areas used bins can be purchased cheaply. Finishing the interior may be more expensive than a square home, but a circular home offers many other advantages.Building a new bin varies by region, but estimate about $30 dollars a square foot – much lower than a stick-frame house (though doesn’t include the cost of finishing it out). One might also find a used grain bin – bins up to 36 feet in diameter can be moved without massive disassembly, and 18-foot diameter bins can be moved with ease. Be sure to use new bolts when reassembling a bin.Building in a circular structure is a very efficient use of materials: one gets a optimal amount of living space given the building materials. Trouble is, modern construction is based on rectangles. The good news is that gypsum drywall can be “curved” but cutting the paper backing at specific intervals – or use thin sheets of fiberboard (which bend easily). Kits for agricultural grain bin access can be easily adapted to architectural doors and windows. One advantage of a grain bin structure is that it never needs to be painted. The galvanized steel will oxidize and form a tough dull gray covering (although tears, punctures or other damage will need attention to prevent rust). Your foundation can also be a galvanized steel plate – though a concrete slab or pressure-treated wood may be less expensive.
In cold climates, consider “nesting” a smaller bin inside a slightly larger bin. Fill the gap with closed-cell expanding foam to form a windproof, weatherproof barrier. Be sure to include windows in such a design, since the foam will form an air-tight barrier that requires additional ventilation.