Building

A Wholly Different Way of Building

by Scott Howard

In arid regions of the world, we can often see architecture made entirely of earth. These buildings usually employ adobe bricks to create vaulted and domed ceilings, adobe for the walls, and stabilized earthen or lime plaster for the roof. These buildings require some maintenance, but are by far the most ecological architecture on earth. However, the question most often posed against this kind of architecture is whether or not it is applicable to areas beyond arid regions. In my eyes, this one of the most important questions and challenges in architecture today. Can we create viable structures of nearly 100% earth in wetter, colder areas? Whoever can solve this problem may stand to gain massive wealth with these massive buildings. Building codes aside for one moment, let’s look at some possible solutions to these questions.

1) High-tech Coatings

My first impulse was to use specially engineered layers of waterproofing coatings that also allow water vapor to escape from the interior of the earthen material. Everyone knows that applying waterproof cement to earthen material will crack and fail due to build up of condensation on the underside which erodes the earth material from the inside. Plus, with tonnes of earth overhead, we’re left wondering if there might be water getting in somewhere that could cause saturation and failure of the roof. There are, however, a few products being used and developed today that show a lot of promise for waterproofing earthen materials without problems.

Reapplication may be necessary every few years, depending on the amount of water present. Examples of such products can be found through two European companies called Keim, and Arcilla Research. The results look promising, and perhaps some of these strategies can be used to create earthen roofs in wetter climates at some point in the near future. Along a similar approach, earthen roofs could be covered with some type of high-tech goretex-like material.

2) Float the Waterproof Layer

Another option someday might be to create low-cost, small space frames above earthen roofs, and attach the waterproof roofing such as metal or EPDM there. This would allow airflow for water vapor to escape, and prevent condensation from eroding the structure. I don’t know of any examples of a building that uses this method currently. Let me know if you find one.

3) Shingles

This amazing building technique allows water to shed while still letting the earthen material underneath to breath. The shingles themselves could be ceramic, thus lasting indefinitely, and could be reused should the building ever be taken down to build a different building.

4) Skybreak Dwellings

This little-known housing strategy was thought of by Buckminster Fuller.
The entire house could be enclosed in a clear greenhouse-like structure.
This has many advantages in the northern climates. First, it could keep all precipitation from ever hitting one’s house, so if it were made entirely of earth it wouldn’t need any protective coating at all. The occupants could control the amount of water in the gardens around their house by using irrigation from possibly a catchment tank. The skybreak dwelling, although pretty high-tech, could pay off rapidly because it would heat the ground beneath the house area and over years raise the ambient temperature of that spot on earth significantly. A few degrees
could make a huge difference in temperate climates for growing season and heating in the winter.

Keep in mind that an outstanding solution may involve combining several of these methods. Now that I have shared these ideas with you, please share your experiments with me via comments below!

37 Comments

  1. Hi Scott!

    Thanks for this post.

    We at OzEarth are considering exactly these things as we speak – we’re working towards building a number of Superadobe Earthen domes, very like the one pictured above.

    We’ll keep you posted, but shingles or a frame roof like a fly on a tent are the most interesting options up to the moment!

    Cheers

    HT

  2. What about cement coatings/stucco over earthbag buildings? My understanding is that that’s what often done. Do the bags eliminate concerns of structural failure due to moisture accumulation?

    Similar to some ideas you mentioned, my first thought would be to put up a simple “false-roof” over the earth structure. A metal shed roof would be fairly cheap, simple, and good for rain collection.

  3. Job,
    I met Magnus to discuss this amazing concept, but it turns out that at the moment, there has only been success on material the size of a small stone, so it will probably be a very long time before this idea becomes a reality and be used to create a dwelling.

    In the mean time, I think Buckie’s concept is the most practical, but recognise that the materials to build a skybreak may not be available/affordable and hence Scott’s article is very timely.

  4. I have a book on earthbag building, although so many more on strawbale. One thing I noticed from the earthbag book is there is a size and dimension limit to the the dome structures. I’m not sure I could have fit a family of four in one.

    What I’ve done is put the book back on the shelf in the collection as I really want to slowly get some cob building books or resources as well. My current impression is I would build a cob/strawbale/maybe timber hybrid type of house structure if I had my dithers.

    Cheers,
    Peter

  5. I just returned from a workshop at Cal-Earth. They are also looking for suitable solutions to the waterproofing issues. Their current system uses tar emulsion over the base render coat, then one or two coats of plaster over that. This is OK (sort of) in the USA, where tar is both commonly used on roofing, and very cheap. Not so in most other parts of the world.
    All the hi-tech solutions are, again, ok in a western, affluent world.
    @ JBob – Cement – based coatings, while immediately accptable to building inspectors, are an anathema to any earth buildings. Cement renders do not expand, or breath in concert with the construction methods.
    @ lee hewson – Lime renders have been used for centuries, biggest problem is the lack of people who actually know how to use lime correctly. PS – Adobe and Cob are totally different building methods (sun dried bricks mortared together vs cob “lumps” integrated in “lifts”)
    @ Helen Thomson – I’ll be in touch with you shortly, one of the things that was discussed at Cal-Earth, and shows a lot of promise in certain conditions, is “rep-tiles” – these allow for and work to control, the natural cracking tendencies of earth based renders.

  6. Thanks for the comments and I am glad that my post stirred up some thinking.

    In fact, I left the Magnus Larson Ted talk out on purpose to see if anyone else would notice! Really the bacterial cement idea spurred me to write about these other options I outlined.

    Also, I should have mentioned Lime plaster somewhere in there with the high-tech coatings, because it really is amazing, and one of the most promising options, also one of the oldest techniques. I believe there are rather large and old earthen domes in the middle east that use lime on the roof, with very long-lasting/ little maintenance results.

    And I also forgot to mention firing the entire structure, which I think makes the exterior much more water resistant than before firing. Unless of course you were to wrap the entire building in kiln insulation, which has been done, and you can get a good low fire quality on the exterior skin.

    Often simple solutions are the most elegant and long-lastinng, I think.

    And yes, you are right to call up Ianto Evans. He is a fun person to talk to anyway, and can always point you in the right direction.

    Lastly, I would love to learn about more research on technology similar to what I posted about. For example where can I read the papers from UCLA about the bacterial cement process?

    -Scott

  7. Oh, and one last thing,

    Yes, cement plaster over earthbags works well and is, I think, somewhat acceptable ecologically if you keep everything else less energy-intensive. I always use as little cement as possible, but I like how it performs over earthbag when done well.

    Everyone talks about ‘ecological footprint’ these days, and I agree, but I think ‘handprint’ is equally important.

  8. I was recently at a school where we built a cob classroom. I didn’t stay around for the plastering finishes but please visit my friend’s youtube channel for some really informative videos on the process and other builds that he’s been a part of including EcoSan. Especially check this out [https://www.youtube.com/watch?v=y7C27W419Qo&playnext_from=TL&videos=IfKYLsxaVzQ] on how to make a waterproof coating with Bael and Jaggery.

  9. Hi Scott, nice article.

    “earthen roofs could be covered with some type of high-tech goretex-like material.”

    Im currently building an earthbag dome at San Miguel de Allende Mexico as a classroom for a local school in the rural area, im using a material called Terracrete: tepetate(like a clay) and aditive form a cactus, and cement. i dont think its a high end mmaterial but the finish is like a vitrified stone and is also waterproof and very very hard, one guy here provided this material and i am having good results using this material for coating the dome i thought you may be interested and i wanted to let you know.

  10. I looked into lime plasters when talking to local builders concerning straw bale buildings. They seemed convinced the the lime available in Australia was not up to standards (I have since forgotten the technical details) compared to the lime you can get in the USA to do your rendering work on straw bale houses. They were doing cement renders of some sort on the straw bale buildings they built. I had previously heard some bad things about the cement renders (cracking, breathability, etc.) so I did not pursue straw bale any further.

    I have a design I am currently looking at that is much more conventional based on some drawings in Bill Mollison’s book (an older Introduction to Permaculture I believe). I like the idea of the bedrooms on the south and living area and kitchen on the north (along with bathroom next to kitchen). It keeps all the plumbing runs very short (kitchen next to bathroom) and the majority of the electrical needs are concentrated in the same areas. 35% glass coverages on the north wall (for latitude -35 region), no glass on east/west, and 3 small glass windows on the south for the bedrooms. I’ve been looking at heat pumps as they claim more efficiency than traditional gas water heaters but in electric. This to combine later with a solar array on the roof.

    I’d like to say I had a kit company ready to go with an offering anyone could purchase if they were wanting a design out of Bill’s material, but I’ve not had much communication back from the designer but I have a plan B.

    I’f anything comes of plan A or plan B I’ll let Craig know and get an article up on PRI.

    In the mean time I’m keeping my straw bale and cob or hybrid options open for the next house as I give myself 10 years where I am before making the move into sub tropical and rural property.

    So keep the natural building articles coming as I love keeping up with the latest developments.

    Cheers,
    Peter

  11. Hi all

    @Don – look forward to hearing from you – my partner is about to go and do an extended stay at Cal-Earth!

    @everyone else – thanks so much for all the info and leads! Feel sure that it will be possible to come up with a low hand- and footprint solution.

    Cheers

    HT

  12. See this link:

    https://www.sciencedaily.com/releases/2009/06/090605091856.htm

    I’m sorry this link is not related to the topic discussed here, but as I just came about this new invention i want to share it. Because earthbags are, as I can understand, most relevant in arid areas, where water recourses are limited. An earthbag house in combination with this invention to ecstract water from the air, should be an ideal combination for desert living!

    F.ex. the air in the Negev Desert of Israel has an average moisture content at 64 %, meaning 11,5 grams of water for one m3 of air.

  13. 2 existing technologies to throw into the mix: shade sails and aerated concrete.

    Living on a sailboat in the subtropics, I can tell you that no matter how impermeable your roof may be to the rain, the sun is a force to be reckoned with. Even the pure white deck of the boat will be literally roasting by 11am. Even white corian counter top and stainless steel will be very hot, heated only by a column of sunlight that’s already passed thru a tinted window. I don’t think you want a waterproof brown roof conducting heat to your living structure; I suggest a white or silver layer to deflect as much sun as possible, and you want that layer suspended above your living structure.

    So I would put my 2 cents on a tensioned tarp, like the rain fly on a tent mentioned above. So long as the tarp sits a few feet above the roof, air convection will help dissipate the heat before it begins to soak into the roof structure. Water catchment is simple with a tarp, or network of tarps, as well. The readymade solutions are known as [google] shade sails. You’ve seen them before. They are functional, attractive, and relatively inexpensive. There are some more advanced models for sailboats that use air bladders much like those of kiteboarding sails for semi-rigid, light weight structure.

    Once you’ve deflected as much sun as possible, again for the tropics and sub-tropics, you want some R value. The readymade solution is AAC, aerated autoclaved concrete. Concrete blocks and panels that are full of tiny air bubbles, basically a light weight concrete foam that can be at once load bearing and easily drilled or cut with a hand saw. Made by adding aluminum oxide to the mix right before pouring the form. There are other methods of creating aerated concrete which use proteins to foam the concrete and do not require autoclaving.

    If anyone is aware of any existing examples that involve the combination of shade sails and aerated concrete, please let me know.

  14. I want to introduce Surfaproof, I was a bit unsecure because it’s a quite expensive product, but I think very effective too. Also it can be bought in bulk, which makes it not so expensive. Here is the link:

    https://www.surfaproof.com/index_en.htm

    The product is made with using ultra sound, and the ultra sound crashes the particles to make them very small, almost down to atomic level. The material used are natural, like lime, titandioxide (not natural but harmless, though the production of titandioxide is extremely energy heavy), etc.

    I spoke with the inventer of this product one year ago at an exebition, a Greek professor in chemistry, and he told the ingredients in the solvent is different for every kind of material to be protected. He told the penetration and endurance of the product is extreme and almost everlasting. The only solvent used is water.

    I remember I asked if they had a mixture for clay plaster, but as far as I can remember they didn’t have this at that time. So maybe I gave him the idea? I see they have today.

    Anyway, I don’t have any experience with this products, only the words of the inventer for the superiority of his product. But because it’s quite expensive, it is most suitable for the western world. But this is ok because here we have the heaviest rainfall as well, in Western Norway the precitipation is 3000 – 4000 millimetres a year.

  15. I also came to think about a lecture I were to with Eng. Pedro Serrano-Rodríguez from Chile last autumn. At the end of his lecture he introduced his new product called Tuna palette gel, which is an extract from a cactus growing in Chile. You can find a bit about it in the end of this document:

    https://www.gaiaoslo.no/Earth%20in%20Chile%20P%20Serrano%20f.pdf

    As far as I can understand his product is not so expensive, and according to him it was superior for water proofing clay plaster. For South America this should be a good alternative, but I understood he could sell this Tuna Palette Gel worldwide.

  16. One form of earthen building that is often overlooked is rammed earth (I’m not speaking of the CalEarth bag method, but the ancient method of tamping soil into formwork in lifts. See David Easton’s: The Rammed Earth House). Today, lime or cement is added to the sand/clay mix for stabilization and this offers some protection against water. Mineral paints like Keim or stucco can be applied (although the finished walls are beautiful by themselves). Proper roof overhangs to protect exterior walls works even in cold/wet/temperate climates. Rammed earth or adobe can gain added water proofing from sealers like Miracote’s Drylook vapor permeable waterproofing penetrating sealer. Miracote also makes Membrane A; a liquid vinyl membrane that could be used with living roofs. A penetrating sealer that works for cementitious materials would protect adobe, but in a wet climate the most practical strategy would probably be to seal the walls and build the roof from another material (metal, shingle, etc.) with overhangs that protect the walls from rain or snow.

  17. Something that must never be forgotten is that whatever protection we use for the walls, in cold climates it must “breath”. This is because the moisture always move from the warm side to the cold side of the wall, and the bigger the difference in temperature, the bigger the damp pressure will be. If the surface doesn’t breath the moisture will heap up in the wall, with fungus and sick building syndrome as a result. And of course we want to avoid a plastic membrane inside like standard in conventional buildings, because this destroys the cobs ability to regulate indoor humidity and to absorb odours and toxins from the room.

    Still it can be an advantage to mix some line seed oil in the inside plaster, f.ex. 5 %, because line seed oil expands 15 % and will create a kind of breathable membrane inside, making the wall drier and reducing the risk for accumulation of humidity above acceptable levels.

    Rammed earth or pisé was earlier very much used in Europe, f.ex. in Romania 85 % of the buildings were made with this teqnuice. It’s said that even a child could evaluate the quality of the soil needed for a building. I’ve been there and some of these beautiful earthen villages still stand, those that Nicolae Ceauşescu didn’t manage to tear down before he was trown down.

  18. Almost all our buildings at Zaytuna Farm are straw bale of types wheat, barley, rice, sugar cane and bamboo, all cob adjusted to shape, mud rendered and lime plastered. I am sitting one now as I type. I have been involved in building straw bale buildings for many years in many locations including rebuilding a village in Iraq with 53 straw bale houses in 2003.
    Would you like me to make a “How to make and use lime plaster easy” video click for the site?
    I could also do “How to make and use cob the easy way” and “How to make and use mud render” and “How to cob, mud render and lime plaster a bamboo wall” might be of interest.
    Let me know people.
    Geoff

  19. Hi Winston!

    This link might interest you:

    https://www.aercrete.se/

    With this technique you can get a concrete with a W/C ratio at 0,4 which is exactly the amount of water needed for the concrete to harden, not leaving any pores in the concrete from water evaporating. This makes the concrete very water repellent and not vulnerable for freezing craks. Also the aercrete can give some insulation because of the air bubbles. Because of the rough structure of the surface even natural plasters can add to aercrete, like lime or lime/gypsum plaster. And the aerocrete is so soft that it doesn’t create hollow eccoes.

    Still, cement makes up 5 % of the CO2 emissions in the world and can hardly be produced locally, as permaculture principles claim. Se here for more: https://www.permaculturenews.org/2010/05/09/letters-from-chile-the-adobe-house-and-potty-training/#comments

    And aerocrete will NOT creathe a breathable wall, even it will help some to add a natural plaster inside, quite much for 24 hours humidity regulation.

    But why earth domes are so good in warm climates is because of their thick walls that also are a part of a thick roof, and the heat can therefore not penetrate to the inside before night. This effect can also be useful the contrary way in cold climates, though you need a long time heating if the walls become too cold. But when warm they stay warm a long time, and radiant heat from walls feels more comfortable than any other kind of warmth, meaning you can have a lower indoor temperature, which is more healthy.

    The heat reducing effect will be utterly strenghtend if you add an insulation layer outside the wall, f.ex. maths of hemp or line seed straws. But of course, sail sheeds will help as well. But what happens with this when the desert storms come in?

    Metals must be avoided in cold climates because of the insulation to the ground. This mean vagabond electrisity cannot find their way to the ground and will be accumulated in metals, like arming iron or iron sheets. Also metals will catch up radiaton from mobil masts etc. If using metals the metal must be connected or earthend to a cobber line you dig around your house to frost free level, like 100 – 150 cm ounder ground here in Norway.

  20. Geoff Lawton, a splendid idea! I had added to a course in natural building in August that was cancelled because of too few participants. Some videos in natural building here at this site cannot make up for practical experience, but it will help. My knowledge is just from reading, videos are between reading and practice, and hence a better solution.

  21. Geoff, can your videos in the store be downloaded or do they have to be shipped? I’m in the US and have been able to order books from local vendors but hoping to download the dvd’s, especially the one with subtitles.

    Øyvind, thanks for link. There are quite a few options for buying readymade aerated concrete using proprietary methods, hoping to find a diy method that can be done on site using local materials. Seems crazy to ship readymade concrete blocks / panels over long distances.

    (Just noticing that both of my above replies are attempts to avoid shipping costs.. the first one high tech, the second low tech.)

  22. Geoff, yep these would be great. also, if anyone knows of any strawbale construction going on in within 200km of brisbane id love to get involved. reading books is great but id love to get some practical experience.

  23. What about seismic factors?

    A couple years ago I attended a lecture at the University of Minn. architecture school on affordable housing in the third world. One of the groups involved was working on simple earthquake resistant designs. They were working on reconstruction of housing in Bam, Iran.

  24. If not for Australia’s maddeningly notorious to deal with local councils I think I would be still proceeding with my original idea of a straw bale house. To get around the red tape in NSW I had to switch to a conventional structure and make sure it fits under NSWs compliant building requirements which forces councils to approve the building plan and gives them a deadline of a few weeks to approve it or find themselves in violation.

    I also found the entire banking and finance structure here compared to the USA tries its hardest to lock you into land and house packages by a licensed builder at fixed cost and conventional structures. It is not an owner-builder friendly environment in the finance markets, nor insurance.

    I wonder if its different up north in NSW in rural areas doing earth friendly construction of dwellings. I have to sit back and laugh sometimes at the regulations here, as if timbre itself was put through the building requirements as a material, it would most likely fail. I am going recycled steel frame for rapid construction time and going owner-builder but its definitely not my first choice or make me the happiest but I’m dealing with Palerang Council down here in the southern tablelands area and have to put up until I am in a position to move.

    Cheers,
    Peter

  25. Hi Peter Dilley

    I’m sorry to tell this situation is the same in all westernized countries, where we suffer so deeply from the mechanistic idea of order, this idea that is the contrary of permaculture and the nature of order:

    https://www.permaculturenews.org/2010/02/04/letters-from-sri-lanka-sarvodaya-builds-sri-lankas-first-eco-village/#comments

    I heard in the radio interwiev with Geoff Lawton posted above that he is very positive for a change to Permaculture in mainstream culture within ten years. I hope and pray he is right, but I also consider that Christopher Alexander is not this optimistic:

    “Living process is by nature morphogenetic. That means a living process acts, in every facet, as a whole, and in all its aspects, is aimed at creating POSITIV SPACE, is aimed at making form coherent. A living process is oriented in its entirety, towards the creation of wholes.

    The present-day piecemeal and fragmented processes of our society, are not oriented towards creating wholes. They are highly organized, yes. But they are not oriented, in their substance, towards the creation of living wholes. They are oriented coherently, but towards making money, or creating power…other matters entirely.

    How then can this too-rigidly coherent machine gradually be changed? Is it possible for a merely piecemeal process, grafted into the existing fragmented system, to change it gradually towards a morphogenetic process, much more like the idealized living process I have defined earlier? If that is so, then we may face even more difficult hurdles, before we can succeed.

    Once again, we are led to the realization that a piecemeal modification of society, along with the simple lines envisaged in chapter 18, will not be powerful enough to work. It will not work because the force and integration of present life-destroying process is so massive, and so thoroughly organized. What we became used to in the 20th century as the process of development, prevented people from acting according to their feelings, still to this day prevents people from acting according to their feelings, still to this day prevents people from shaping the environment in a way that is appropriate according to the global nature of the whole – and prevents the successful evolution, as unfolding would suggest, of buildings and landscape.

    Thus the 20th-century process interrupts the process of paying attention to wholeness, the unfolding of wholeness, and the process of shaping the surface of the Earth correctly. At the same time it also robs people from the simple joy of acting appropriately, in a way that is fulfilling.

    The connection between the two – the rise of developers and the loss of feeling – is not accidental. It may seem ridiculous to say that the world will be improved – in its organization – if people are able to act, at every scale, according to their feeling. But it is the WHOLE that is being damaged by the loss of feeling. By not allowing people to act according to the global feeling of the situation, that means that each of the prevailing processes – whether they have to do with development, or land purchase, or transportation planning, or banking, or speculation, or construction-contract administration – they all, in their present form, have the capacity to damage feeling and therefore to fly in the face of the interests of the global whole.

    Worst of all, perhaps, is the fact that the process which exist – which we now take for granted – in many cases virtually outlaw living process, make living process fundamentally and practically impossible, impossible even to imagine, since the ground rules of the processes we know today have driven them out so far.”

    The Process of Creating Life, by Christopher Alexander, page 524 – 525.

  26. Hei Øyvind,

    I’m really enjoying the video you put up before on david sheen’s web site. I’m still watching it.

    I agree with what you are saying regarding change. I can not speak for Geoff, but I do wonder if his statement around ten years is based in any way on a predictive outlook to when the pressures from the beginning of the end of hydrogen based economies will happen.

    I’ve talked to a few owner-builders in the area just around the financial institutional pressures and they only got their finances arranged with traditional lenders by purchasing as investment to get the loan and then built later after the loan was in place.

    There is always a conformity pressure in society, even in the smaller villages. The councils are worried about fitting in with a preset look and feel and not deviating too much as they have to worry about their own property values although they don’t directly state so. Conformity breeds perceived security and sense of identity so I can understand how these regulations develop.

    Its just a bit of a shame you have to go very rural to gain a sense of freedom from people telling you what to do when it comes to choices surrounding living structures and land use in general.

    Takk

    Peter

  27. @supachupa: Ah, didn’t know that. Too bad, but I still hope something comes out of this idea somewhere in the future! :)

    @Øyvind Holmstad: Thanks for the link! Interesting stuff

    @Everyone else: I don’t have much to add to the discussion, but again: very interesting stuff, thanks for sharing your thoughts.

    Has anyone here read The Barefoot Architect? It’s basically “my own first eco-village” in book-form, with very clear pictures, and just about every possible topic covered.

  28. If somebody in Romania read this I hope you can help reclaiming Romania as the leading earth building country in Europe. When I was there the beauty of your ancient villages and towns moved me utterly, but so did also the extreme ugliness from the communistic era. Luckily Ceauşescu’s hand didn’t reach to Maramures in the North, with the greate wood working traditions you are so proud of today. But you should not be less proud of your greate earth building traditions, which Ceauşescu managed to destroy almost complitely.

    If somebody could make an article for this site about the grate earth building traditions of Romania, that 100 years ago made up 85 % of all building in this lovely but ravaged country, creating villages with the full meaning of the quality without a name, defined by Alexander in The Timeless Way of Building, it should cheer my hearth.

    Also such an article could fill romanians with pride of their past, and give hope to so many poor people now dreaming about living in a “modern” concrete building. Realizing that they can build the true quality of life right out of their ground. To see that their dream about the oil intensive comfort zone of the western world and EU is a false dream. That they can make something much better, a life zone, provided by Mother Earth, guided by Permaculture.

  29. Would it be possible to use either aluminum pop cans, or 2L plastic bottles as a roofing option? I am trying to think something for my rainy climate, and I thought of cutting the top/bottom off, then making a sort of shingle out of the straightened out material and making a simple wooden frame around the dome to attach it to. I thought a simple option for the frame would be using pvc pipe or flexible piping, which would allow adequate space between the surface of the outer wall to allow for evaporation.

    I’m sure there are flaws with this idea, and that the can/plastic idea would not last very long in sun/rain exposure… but what do you think?

  30. I’m in Haiti gettin ready to build a small test dome. The conventional wisdom is that you can’t waterproof these things. I’m going to try something really simple: Over the earth bags I am going to paint on some commercial elastomeric roof sealer, like the kind they put on the roofs of mobile homes. I did this in Idaho, and nothing else. So far, that building is doing fine. The roof coating reflects over 95% of the UV light and protects the bags. I put nothing on the inside of the building, only the exterior. That building is a 12′ unstabilized earthbag dome.
    For Haiti I want to go a few steps further and apply an earthen plaster over the roof sealer coated bags. I’m going to make sure the plaster doesn’t physically connect with the ground by putting a small gravel mound around the base of the dome. Then I’m going to paint over the plaster with my roof coating material.
    That’s it. Maybe I’m being naive, but so far the models I’ve built have been showing no sign of water penetration or serious cracking. I’ll let you know how it goes… If anyone has tried something like this before, let me know.

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