We can all learn a lot from each other, and so I’m encouraging everyone to send us their earthbag building experiences (favorable or unfavorable) so we can share the information with other readers.

Earthbag builders are regularly experimenting with new ideas and techniques. If you have learned something interesting and think it can benefit others, please leave a comment to this post. (Click on Comments below.)

If you are an engineer and would like to volunteer with earthbag testing or writing technical reports, please email Kelly or myself from our About Us page.


Comments

Call for Greater Earthbag Sharing/Testing — 19 Comments

  1. I have been following another interesting project. A guy who goes by the name ghost32 has been building a vertical wall earthbag home in Arizona these past few months. Here’s one of his most recent post
    Mind you, I am slightly worried for him as he doesn’t appear to have used any buttressing or the like.
    Anyway, might be an idea to see if he wouldn’t mind you putting his project up in the project pages.

  2. This website link (apparently through my name above) shows a few photos of a large Superadobe dome project near Barstow, CA that I’ve designed and constructed (to the point of base plaster on exterior, finish will likely be later in spring). It is 24′ inside diameter at base, rising on ‘catenary’ curvature to sloping truncation (5′ wooden plug accommodating stove and vent pipes, 2 small skylights and escape hatch) around 16′ above grade, utilizing 16″ Cal-Earth tube-sack. This was attempted as a fairly aggressive exploration of structural potential with this system in several capacities, and quite cognizantly surrendered to the tests of time. I can only stand behind this as an artist of sorts, as it is beyond most established protocol of construction. And to exploit the obvious morbid humour, not I nor any shall lie beneath it, as in residential habitation, until it, or something comparable, has exhibited sufficient seismic resistance. I’m curious what information/documentation would be most interesting/useful to the wider community of earthbaggers from this experience (and ongoing)? Thanks, and encouragements.

    • Great project, Benjamin. The large south-facing window will add a lot of solar gain. But this would be way too risky in earthquake zones, as I’m sure you’re aware.

      I hope you’ll submit it for our Projects page: http://www.earthbagbuilding.com/projects/projects.htm

      Just write a few paragraphs about your experiences, building details, etc.

      Update: Kelly has added lots of new text that Benjamin has provided. If you saw it earlier or if you haven’t seen it yet, be sure to take a look: http://www.earthbagbuilding.com/projects/benbrown.htm

      Note: I like how Benjamin framed the loft floor. This will add a good bit of seismic resistance.

      • Okay Owen, I’ll do that soon. I would also like to know of anyone’s favorite forum for more involved discussion on topics that may arise here…perhaps the new earthbagnetwork.com site? I will set up a ‘page’ there to carry on about the merits/liabilities of my dome design, as in fact I don’t concede that it is ‘way too risky’–it is just a few steps ahead of what’s been tested/proven but still in line with my personal/intuitive sense of what’s possible. I do genuinely welcome contrasting opinions and data so let’s find a space to elaborate. I’ll watch for suggestions and post a link when chosen. Thanks!

        • I just joined the earthbag network. There are a number of worthwhile discussions taking place, but it’s clearly still in its infancy. Only a few members so far. Several people have complained of login problems, myself included. Just keep trying. Not sure what I did after about the 7th attempt, but it suddenly started working. There’s also a lot of distracting marketing posts, not sure what that’s about, but it looks spamish.

          What are you using as a lintel over the windows? Flickr is dirt slow right now so I can’t check. It looked like you’re using 2x12s. If so, then all the weight above each window is being supported by just 1-1/2″ of hem fir, or whatever. Earthquakes can easily topple something like this.

          But like I said, in non-seismic areas this is a good way for adding daylight.

          • re: the lintels, they are essentially low-rise ‘box beams’ of 4- 2x’s (2×4 on the shorter 2-3′ spans, 2×6 for 4’+), with cross members and ply base/cap. I have a “maximum total load for doubled 2x header” (deflection=L/240) at 1000-1500 PLF from span table. 1’x1′ of filled bag would be something over 20′ high to reach that point of load, which is still only very minor deflection and not failure. Also, the way a bag (or any monolithic type) wall distributes load over an opening is such that only a ‘bell curve’ section of overriding material is directly bearing on the lintel, not an indefinite upward projection of the opening’s width. I should make/find a diagram perhaps. Anyways, I agree that substantial southern glazing is a key feature that can be trickier to incorporate with bag systems, but I’m mostly pleased with the results here and encourage others to expand the design alternatives. More in a writeup to come…

            And from my experience, the EB network has been smooth and inviting. No trouble signing up or logging in, no spam or adverts that I’ve noticed. Very well designed for flexible use. Any other suggestions for discussion fora?

          • That’s certainly stronger than what I thought you were using. (Flickr still not loading after hours of trying.)

            Still, earthquakes are capable of incredible damage. Try doing a Google Image search of “earthquake houses” or something similar.

            Yes, there is a distribution of forces over openings in domes. But there’s also risk of these lintels being knocked out in an earthquake. I hope I’m not sounding too critical of the design, but large openings will be the weak link in any dome design.

          • Not at all, thank you! This is a pretty important conversation, and I don’t claim to have investigated every pertinent thread of evidence/research/calculation/speculation…so just your general ‘sense’ of things coming from a unique, and probably deeper, background is valuable. I actually did a lot of looking at live quake videos with that curiosity in mind, but an earthbag dome is such a unique system that things don’t translate well. Can anyone add info/links regarding the extent of seismic testing/engineering that has been done with bag walls, and particularly domes? For beginning investigators, the wikipedia page on ‘seismic engineering’ gives most fundamental principals, and clued me into another huge advantage of earthbag: the vibration damping effect of non-fixed stacking (the limited slip and bounce freedoms between courses). And regarding the ‘pop-out’ potential of header/lintel, definitely a good tie-in is adviseable, even though bags can be set to very effectively lock in these elements. In my case, the ‘trimmer’ boards have 2 or more 1/2″ bolts into spiked metal ‘sleeper’ anchors, and the top of each ‘box beam’ is essentially a bed of nails on which the first spanning course of bag was then layed (with contiguous barbed wire also serving as a tensional restraint). Note that this entire load transferring structure is in the (slanting) plane of the wall, with added framing for the upright window/door box itself.

  3. An anonymous reader submitted the following comment. I don’t have time to confirm the details. Please do your own research if interested.

    Anonymous wrote:
    Superadobe bags, like most sandbags (earthbags), are made of Polypropylene.

    If you google for Polypropylene MSDS (material safety data sheet) you’ll see that only concerns for safety come from burning polypropylene in unventilated spaces (and coming in contact with hot, melted , burning plastic).

    It is a very safe material, its used for everything from water bottles, pill bottles, candy containers, yogurt containers, plates/forks/spoons, blankets, shirts …
    thermal underwear

    100% Polypropylene is not reccomended for clothing/bedding if there realistic risk of explosions (refineries, war-zones) because it can easily melt onto your skin (imagine that, a bomb goes off nearby, you’re uninjured from the blast and shrapnel, but your underwear has melted into your skin) which requires surgery to remove, and carries a high risk of infection (the part that can kill you).

    Ok, back to http://en.wikipedia.org/wiki/Polypropylene#Degradation

    Polypropylene, when exposed to UV breaks down into
    http://en.wikipedia.org/wiki/Aldehydes
    http://en.wikipedia.org/wiki/Carboxylic_acids

    So if you were to build your earthbag house in a hermetically sealed sun room (airtight), and if you were to leave your polypropylene walls exposed to sunlight to the point that they fall apart (say 1-3months for non-UV-resistant polypropylene). And all the polypropalyne has all dissolved, and then you walked in there and tried to breathe in all the vapors, there is no chance it would do you any permanent harm. Ok, you might be disturbed by the smell and fall and hit your head, or you might get an astma attack, but if you leave the door open for 5min you’ll be fine.

    To simulate what this unlikely scenario might be,
    8 fl oz of acetone nail polish remover
    get a shallow pan/tub/bowl and pour,
    place pan in middle of room,
    wait till noon and then pour acetone,
    leave room.
    Come back hour (or two) later and acetone will be airborne.
    open door and walk in then say “fooey that stinks”,
    then open a window and let it air out.
    Be careful in your room selection, acetone is a solvent, it might ruin the finish on your plastic items, or peel some stickers…

    in conclusion, practically everything will outgas (http://en.wikipedia.org/wiki/Outgass)
    but you’re safe if you open door/window daily (like when leaving/entering). Polypropylene is very safe.

  4. Another test that would be useful to some of us would-be earthbaggers is measuring the VOC and other fumes from earthbags. For various types of bags, polypropylene, grain/seed bags, burlap, etc.

    • I agree. Do you have time to check on this? Most products have a materials safety data sheet that shows information like this. If there’s a warehouse fire, for example, firefighters will know how to handle the fire and protect themselves.

      material safety data sheet at Wikipedia: http://en.wikipedia.org/wiki/Material_safety_data_sheet
      free search: http://www.msds.com (I tried various combinations of sand bag, sandbag, polypropylene bags, etc. with no success. However, there are 50 polypropylene products that you could search more carefully and maybe there’s something similar.)

  5. Two groups have just expressed their interest to help with testing. One group is with Engineers Without Borders. They plan to do an additional compression test and post it on our Testing page. http://www.earthbagbuilding.com/testing.htm

    Another group wants to test the bullet and blast resistance for military and commercial use. They plan to video the demolition process and put it on YouTube.

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