Alternative, locally "green" source material is here considered for structural considerations. Self-sufficient qualities always intreaged me along with affordability for "struggling artists" types. The use of soil and raw logs has inhtrigued me over the decades, but discarded materials suitable for re-use has usually proven more viable and time saving. Yet the notion that on-site dirt can be rendered into a valuable structural material theoretically proves very attractive. Here i explore simple structural examples to present some aspects which influenced me. First is a simple vault, with rounded corners, arched roofing and a slight overhang. Rounding will tend to diffuse dynamic loads of stress, (as in the egg shell "reinforcement principle"). So something like a 300 square foot interior (or less than 30 meters square) will require a great deal of material.
Heavy, compressed earth alone would require much more labor effort. Consider an example of lighter material. Strength with some insulation value might be achieved with commonly found, raw materials. We might assume that a selective, slightly insulating, bioi-mix building material will weigh in the neighborhood of 60 pounds per cubic foot (when dried, or 960 kilos per cubic meter). Such a configuration then would require installation of nearly 70 English tons or 63 metric tons of material. That is a lot of material to handle, most especially if placed by hand. Lighter mixes might yet be obtained, depending on the exact nature of available bio mass or recycled material.
Without a break-through it would require endless, tireless work for a "do it yourself-er", to say nothing of temporary form work or false work. Yet i would argue that given some appropriate tooling (along with required financing) a system of "locally sustainable material" could prove interesting. Powerful tools need development, unless one could find an athletic team to accept the challenge. It is more work than building with stones or sticks. Slightly favorable here, is reduction of the carbon foot print, as this class of materials largely reduces carbon footprints. Financing of special tool development, for more harmonious building systems, at least for homes, could help. I never found fianancial help, for any effort like this, however.
Next above is the same general layout in a smaller space. However, thinner walls require improved material qualities. Material expense is therefore added. Strength, thermal-conditioning and insulation value can be obtained with thick walls. Lower costing material is possible or made possible with the right equipment. Or perhaps some people will appreciate the long-hard-muscular-labor (as a substitute for load bearing exercise)-- After all, it is altogether possible that a person might like to adopt a physical exercise work-out, while at the same time accomplish something useful, a building. It might provide a more inspiring workout and harmonize human health with, human productivity, synergistically.
As to mold and pest potentials with locally available dirt walls-- I doubt there is much risk, given appropriate steps are taken, for the given region. Different climates, all have particular issue. I have heard of far too many complaints made about green roofs and wild gardens generally. These complaints, so it seems come from sterile styles of living. Fighting germs exclusively with artificial chemical toxins, tends to strengthen the germs in time and also weakens the human orgaqnism. Mastering germs and pest with natural means, wins the battle of evolutionary development. I would say each known issue has simple solutions. Insistent-complainers are likely to be the people with dark clouds following them around. No matter what, the gripe of the day manages to plague them. It's more psychological and less a provable fact, that eco-systems in a house structure, or weeds in a garden "are bad".
Next above is my visualization inspired by a friend. A similar vault was modeled with thick columns, to allow for less refined and less industry-standardized masonry. A TeePee like roof is positioned on top. A sturdy and an emblematic wind generator blade design is also suggested for the top. The wind blades are meant to replicate a TeePee peak with poles sticking out through the top. It has been assumed in these models, that windows and doors would naturally be added.
Getting back to what is possible in basic building. Even as a youth , it seemed to me that building is largely a job of placing materials in-place. Lift, carry, place-firmly for permanence. Yet this is tons of lifting and moving work. Moderns seem to prefer pumping iron in a commercial gym or running along a road way instead. I advocate so called manual labor as a way to exercise and create value at the same time. Expand the world assets and burn off calories at the same time. My purpose here primarily considers common building potentials with emphasis on locally available materials. Respect is intended towards each preference or each culture, while borrowing aspects for new composite materials. I will conclude with some thoughts resulting from a recently published book.
Sod , adobe, stone, cob and even cord wood construction each offer appealing features. Wise use of many cultural traditions should improve human impacts on the planet. Otherwise humans will face resource crises, Water sourcing is becoming a critical issues in many world-wide regions. If it were easily produced, the Arabs or Israelis would have huge production plants presently greening the desserts. They can't even distill ocean water very economically! In terms of taking water for granted, i recommend you read the book about the dust U.S. bowl, the prediction of Ten Bulls, the locust plagues and the "Nesters". I was amazed by this story in "The Worst Hard Times" by Timothy Egan. An amazing story, for me, full of insight as to how hard the lessons of water really are. This story pertains to the high plains from the Texas Pan Handle to Nebraska, where the buffalo once roamed freely and the grassland was ruined by short sighted profit motives. It also described the problems of earthen "dug outs", for people needing to settle without knowledge of the consequences, (which became the dust bowl). My point here being that these dug outs were described , as using only tar paper, to seal the interior of homes from the out side and from the prolific eco system of the very fertile, natural soil, of that time. (Before the dust bowl ruined it). Tar paper is not nearly durable nor likely to seal out centipedes. Finding some form of durable sealer should make good sense. A relatively small amount of commercially available cement paste should improve the seal much better than tar paper alone. I tend to favor a thin layer of ferrocement at the minimum. (Here is a page on very simple, thin ferrocement wall work). Door and window casements are reasonably priced or at the least, possible, for the dedicated self-builder to make, (even from scratch). Yet having a durable seal is very important, because a wide range of pests are highly attracted to human food supplies, generally. Yet completely manageable with a good house-seal. A home seal which can provide harmony with nature.
Perhaps one of the finest sod homes built. Located in Nebraska, 1882. I'm especially impressed with the buttressing corners to reinforce the earthen structure. Innovative solutions where and when other materials were readily available.
A company with interesting "cast earth" technology, along with professional services: http://www.castearth.com/
The author of this page is just one innovator among others. Each innovator may focus on specifically preferred aspects. My interest is very broad. I offer customized computerized modeling which may assist people who wish to communicate these cost saving concepts to their engineers or builders. I also offer customized assistance from earth work to concrete work. Hire me to contract on customized jobs, large or small. Below are other related web pages which i wrote in years past.
I offer many diverse structural concepts here, a menu with text and pictures together.
index.html (A similar menu with pictures, but without text)
Bo Atkinson, a fifth generation Atkinson in The USA, still building with earth and stone.
Note: These pages are placed in the public domain and are furnished "as is". The author assumes no responsibility for the use or misuse of the concepts in this series. All authorities should be satisfied first, as might be required, by relevant laws, before any building proceeds.
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Tel : 207 342 5796 . . . (Maine)