Woodchip/Light Clay Earthbags — 7 Comments

  1. I live in Alaska and have massive amounts of wood chips available however I would have to truck my clay a fairly long distance. My question that I’ve never seen addressed is how much clay per-cubic foot of wood chips would be considered standard? Does anyone know?

    • Dry mix weight of clay to straw for insulating walls in northern climates = 35/lb/ft3

      Wood chip/clay should be in this ballpark. Experiment to see what works best, buy a book on this building method and/or try emailing the author.

      The R-value of wood chip/clay is around R-25 for a 12″ wide wall. Freezing weather can damage the walls if they’re not dry, so be sure to allow plenty of drying time.

  2. Did you build your test wall? We are thinking of trying this and straw-clay test walls in a shed next year prior to building our house the following year…

    • I think this method has a lot of potential, but I live in a somewhat remote area and never found a source of wood chips. Branches are discarded here, not chopped into wood chips. Need to find someone with a machine.

      You’re building on a tradition going back hundreds of years, so the technology is extremely well proven. It even meets code in Germany where they have some of the strictest codes in the world. Using bags will be even stronger. I would use mesh bags for faster drying. Some external pinning will add a lot of extra strength. This is the same general advice for lightweight bags of scoria, hyper-wattle, etc. Put bamboo or rebar pins on opposite sides of the wall and tie them together tightly with baling twine or cord.

      Please keep us posted on your results. Take lots of good photos and send a summary of what you learn so we can share with others.

  3. Owen, I read in two books about using rice hulls in earth bags but not much more information was given. Since then I was under the impression that rice hulls could be used solely to fill the bags. They have R values of R3 per inch and other great characteristics. Is this an instance where rice hulls could be used in lieu of wood chips with clay? Also rice hulls in my area of the country and free. Any clarification or direction on utilizing rice hulls would be greatly appreciated.

  4. Pingback:Woodchip/Light Clay Earthbags « Earthbag Building Blog | Tree Trimmers Austin

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