Roundhouses get my vote for the easiest shape to build.

Roundhouses get my vote for the easiest shape to build.

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.)


What’s the Easiest Shape to Build? — 26 Comments

  1. Hi Dr. Owen, please can you help me? I want a round house but am confused about bag size. My plan is for a 20ft roundhouse and I guess the walls should be 18inches thick. Should I buy 20inch bags or 22inch? On YouTube you say you use 18inch bags. have a few friends helping me (carpenter and electrician)

  2. Pingback: Fabric Forming « Geopolymer House Blog

  3. Pingback: Three Roundhouses Design « Earthbag House Plans

  4. Why use poly bags when you can just ram the earth? Is it just about labour reduction and being clever? Can you use any clayey sub soil? Do these building perform better in certain environments?

    • Rammed earth requires expensive forms that are only practical for contractors who use them repeatedly. Homeowners can build their own home with earthbags without contractors or forms.

      Yes, almost any clayey subsoil will work. You want enough clay to bind the sand and gravel together. Make a test bag and see if it dries really hard.

      Earthbag will work in any climate if designed correctly. It’s best where there are few building codes. Building codes will greatly increase the cost of construction.

  5. The briefings comment say 15:th will they announce.
    So the final date for the announcement of the winners has been set at June 15.
    The judges and I hope and thank you for your understanding and we look forward to sharing the results with everyone on that date!

  6. why use plastic bags when you can just ram the earth? is it just about saving labour and being able ti use any old earth instead of decent clayey sub soil? Do these buildings work better in certain environments?

    • Earthbags (bags and tubes) serve as flexible forms that can create almost any shape building. Wooden forms are expensive. Rammed earth requires a fairly specific formula. Earthbag building offers a whole range of benefits (few tools required, relatively simple construction, no specific soil, etc.).

  7. It is also a question of what is easier to live in. For example, kitchen cabinet units are rectangular, not round. So are beds, and bathtubs, and tables, chairs, sofas, shelves, etc.

    For a round house, you basically have to custom make a lot of the furniture if you want it against the wall, which raises the cost considerably.

    One issue with earthbags is that building long straight walls are unstable. That means buttressing and wall bracing, which ads to the complexity (and cost) of construction.

    I’m not sure how long of a straight wall could be made without some sort of bracing, but I imagine 3-4m. So, that means every 3-4m you need either a buttress or wall intersection. I guess you could possibly do a pilaster, maybe reinforced concrete every 3m or so as well. A poured column on the inside and outside of the wall, maybe 8″ thick would stiffen it considerably.

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