So far very little has been written about earthbag basements. Earthbags are suitable for basements and other underground applications such as cisterns and rootcellars. Round or curved designs are inherently stronger than long, straight walls, which require reinforcing columns or buttresses.

Earthbag Basement Wall Detail

Earthbag Basement Wall Detail

General guidelines for earthbag basements:
– 24″ wide poly bags (measured when empty)
– lime stabilized soil tamped solid
– 10%-20% type-S lime hydrate to dry soil by volume
– mix lime and soil thoroughly before adding water
– two strands 4-point barbed wire
– rubble trench with French drain
– taper walls slightly outward
– double layer 6 mil polyethylene moisture barrier
– use scoria, pumice, etc. for improved insulation

Build on high ground, and grade the site away from the building. Dry climates are obviously more suitable than wet climates. Use caution — working below grade is dangerous. Temporary shoring may be required. Avoid problem clay soils. The final design should be based on soil tests and calculations by a licensed engineer.

I have one plan with a basement: Habitat Earthbag House


Comments

Earthbag Basements — 19 Comments

  1. Where can I get the blueprint details on the habitat house that has a basement underneath it? Also, I seem to recall quite a few round house plans that had basements. Was this something you did at some point?

    I really hope to find someone who has built a basement using earth bags – especially in a colder climate.

  2. What about filling earthbags with crushed granite? I heard of that too. Round walls seem better than straight. Do you think round walls require butress, or just dead man anchors? I’d think that super adobe would be a better choice. If clay heavy soil is mixed at around 10-15%, would it be like cement and not effected by water as far as stability is concerned? I watched the series on youtube by mylittlehomestead. https://www.youtube.com/playlist?list=PLqweMXveARYCalRJRxdO-8ETdi3DnQIMr

    They used just normal earth, with plastic blocking the outside of the walls, but it was a round building.

    • Granite has been used to fill earthbags and it seems to work well. Round walls do not generally require buttressing; depending on the design they might benefit from the anchors. The long Superadobe bags are stronger. Heavy clay will bind the material very well, but if it gets wet, it will expand and not be as stable. A circular underground structure like in those videos should be very strong, and a wide range of soil fill material can work.

    • Earthbags could be used in this situation, but the logistics and engineering of the project must be very carefully evaluated.

  3. I was wondering if anything has been done with basements, here it being a few years later and all. The other question I had was what if I just over engineered it, instead of adding buttresses just making the wall very thick, like two to three earthbags deep, interlocked of course? Yes I would loose space but I might have a safe basement, what do you think?

    • There are numerous options including making double wyth walls as you mentioned. There’s an earthship earthbag house being built with earth berming/sheltering along the back of the house. They use geomesh between courses like they do to retain hillsides along highways. A good engineer knows about this stuff. Also, a lot depends on your soil type and water table. Be sure to talk to builders before building.

  4. If I wanted to build a straight wall/square basement, how much more would it be compared to a round one?
    How much are buttresses for basements?

    And where can I read more about the lime and soil mixing?

    • Earthbag basements are very much experimental. No one has built one to my knowledge except for small survival shelters. Don’t attempt it without expertise advice, especially straight wall basements.

      The military has tested lime/soil stabilization extensively. There are detailed reports on the Internet. It’s used for such things as rapid construction of airplane runways/landing strips. The experts are the Army Corps of Engineers.

      • Thanks for the response Owen. I might just skip a basement; I’m not one to experiment with such things. I’ll wait until (and if) it becomes more successful and common. There’s plenty to do above ground!

        Though I’m seeing designs of “hobbit holes” all over your site. I was thinking of building one of these, separate to my main home, to serve as a root cellar. Perhaps I could at least do that.

        -Jesse

        • A small, simple structure such as a rootcellar is a great first project. Start with a low risk structure and tackle something larger later.

        • I know I’m late on this answer, but it seems to me it would be pretty simple to incorporate buttresses into the basement wall and have them serve doubleduty as counter space. Lets say your wall was 7 feet tall, a butress of two layers of 18-20 inch wide empty bags would provide a nice workspace (or storage space that doesn’t require bending/crouching to access) built to a height of 3.5 feet would seem about ideal to me.

          Another suggestion is not to make the basement too large, it’s better to have more smaller basement sections with their own floor/ceiling access port and complete walls than to attempt to make one too large. (Personally I wouldn’t build a straight-walled Earthbag basement over 400 square feet or so, but that’s just me.)

          • Those are good suggestions that offer some different options. One drawback to the work bench idea — it would take up valuable interior space. Plus, you couldn’t store anything under the benches unless you used some arched openings.

  5. hi

    Im not sure about the size of the bags to use for walls and for basements, at my place its just easy to get 50cm wide (when empty), it is not to wide for a wall???

    • Most earthbag walls can utilize standard feed or grain bags about 18” wide when empty (close to 15” wide once filled and tamped).

      Basements have to resist horizontal thrust of soil and so it’s better to use larger bags about 22” wide when empty (close to 19” wide once filled and tamped).

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