Roundhouses, especially ones with a lightweight roof, get my vote for the easiest shape to build. This obviously goes against conventional thinking that uses modern materials such as plywood and sheetrock. Sure, there’s a certain degree of efficiency in building rectangular structures with modern materials — they do go up quickly. But the logic falls apart when you start examining the sustainability and cost of these energy intensive materials. Energy prices will almost certainly continue to rise, driving factory made products higher and higher. To achieve affordable housing we need to look at simpler solutions made primarily with low cost natural materials.
And by affordable, I mean $10-$20/square foot. For instance, our earthbag roundhouse is 18’ exterior diameter, 15’ interior diameter, 177 sq. ft. interior floor space. Materials cost $2,045, which is about $11.50/square foot. There’s a modern bathroom, electrical and small counter for the kitchen. It would be fairly easy to enlarge the design a bit and add more durable roofing for another $1,000 or so. Let’s say you wanted an 18’ interior diameter roundhouse. That would give you 254 sq. ft. interior floor space for around $12/sq. ft. Add a little extra for shelving, recycled or homemade cabinets and recycled kitchen sink.
I got a little off track talking about pricing. My main point is ease of construction. To build an earthbag roundhouse you set a center pole and then attach a rope to the pole to check the radius of each course of bags. My Earthbag Roundhouse Instructable explains the building process I use.
(My Instructables have had over ¼ million hits in the last six months. That’s an indicator of the growing popularity of building with bags.)