Archive for November, 2008

It’s our one year anniversary and we’re happy to say we continue to receive and publish new projects, photos and articles weekly.  Because we publish all the latest news, our growth here at EarthbagBuilding.com mirrors the growth of building with earthbags worldwide.

For example, right now we have 31 articles on everything from construction details, dome building, simple shelters, to building with scoria on our Articles page.  If you have a topic in mind you’d like to know more about, please drop us a note by email.

Our Projects page is in a league of its own with over 30 featured homes and commercial projects.  There are many more earthbag projects around the world, of course, but these are the ones we have so far with photos and building details.

Kelly continues to add new images to the Slide Show.  It’s now the largest single source of publicly available earthbag images that I’m aware of.  The photo captions do a good job of summarizing each pic.  So make a cup of good tea, sit back and relax, and take a look at what others are doing.

Also, the site’s success can be measured in our web traffic.  The average number of unique visitors each day has been 821, up from 694 last month.  Mostly we have averaged about 400 or 500… pretty good for a new site.

Judging by this rapid growth, it appears earthbag building is entering a new phase of development and more mainstream acceptance around the world for a wide range of structures.  Please help us spread the word by sending us details about your project.

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Earthbag Building in the Humid Tropics: Simple Instructions by Patti Stouter is a 27-page, step-by-step PDF guide to building with earthbags in these demanding climates. It is well thought out, quite informative, and useful as a basic introduction to the concept of building with earthbags.

She begins with a general introduction, and then moves on to a discussion of stabilizing earth as a construction material and the use of earthen plasters. She points out that “small houses can easily be built strong enough without cement or bitumen. Tests have shown that a careful balancing of the range of particle sizes in a soil may improve strength more than added cement.  Earthbag walls seldom need additives to give extra stability.”


The step-by-step description covers: soil tests, materials, layouts, footings, laying bags, base courses, openings, bond beams, roofs, floors, and finishes. Patti puts forth some general principles for earthbag building in humid climates:

➔ Use as much lightweight gravel as you can afford for cooler, less sweaty buildings.
➔ Use as little wood or metal as possible, to avoid rot and termites.
➔ Use plan layouts that are stable, with curves or frequent piers or buttresses.
➔ Make sure rainwater flows away from the bases of all walls.
➔ Use a vapor barrier below the floor and between any concrete and earth.
➔ Provide a waterproof base course at least 60 cm high.
➔ Criss-cross bag courses at piers and corners.
➔ Provide wide roof overhangs (1.5 m is good).
➔ Test exterior finishes for performance.

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Sandbags have a long history of use in flood control.  United Bags, Inc., for example, has supplied sandbags to the U.S. Army Corp of Engineers and the public for 117 years.

Sandbags play a critical role in building and fortifying dikes and levees to protect our communities.  The bags are low cost and easily transported to the site where needed.  They can be filled with locally available sand or soil by unskilled workers.  A few new inventions have come along as potential replacements, but all lack the time-tested efficiency and effectiveness of sandbags.

sandbag dikeIf you follow the news, it almost seems there’s a flood somewhere at any given time.  And when it comes to flood control, sandbags are the first choice of defense.  For instance, the U.S. Army Corp of Engineers provided 13 million sandbags this year, in addition to those purchased by communities.

The same properties that make sandbags (earthbags) ideal for flood control – strength, durability, resistance to moisture, low cost, ease of use – also makes them well suited for building houses and other structures.

Floods are an all too common reality, so ask yourself this: In the event of a flood would you rather have a wood-framed house or an earthbag house?

Photo by Huitzil, http://www.flickr.com/people/7173680@N03
Photo source: http://www.flickr.com/photos/7173680@N03/1805951815

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Shaping Buildings for the Humid Tropics: Cultures, Climate, and Materials by Patti Stouter, 2008, is a 28 page PDF document that describes how to use ventilation, shading, plantings and insulation to provide comfort in hot humid climates. It includes some discussion of the use of earthbags in achieving these goals.

This is one of the best sources of information about building and living in these challenging regions that I have seen. Patti points out that simple, low-cost buildings can be cool, dry, and mold-free if they are carefully planned. She also discusses the cultural differences that might affect appropriate designs.


She shows how to catch breezes to make the inhabitants feel cooler and to keep the humidity from building up. How to best orient a house to avoid overheating and ways to use landscapping to enhance  comfort in buildings is outlined.

“One of the most important goals is to build of ‘lightweight and low heat-storing materials’ so there won’t be much heat radiated towards the inside. Traditional building materials like wood, grass, palm, and bamboo are cheaper as well as cooler than masonry. But because they rot easily or are eaten by insects, they must be used carefully. Natural materials can be used inside to provide sound or heat insulation. Sea grass, rice hulls, and coconut fibers don’t absorb much humidity.”

“Earth buildings last well when maintained, and are less subject to overheating and dampness than stone or concrete. Earth walls don’t get hot or cool very quickly because earth insulates better than concrete. Heavy concrete walls in very humid areas become frequently damp from condensation, causing algae or mold growth.  Solid earth walls will receive less condensation than concrete because they are less dense, and because they absorb more humidity.”

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In an effort to track down the history of earthbag building, I’ve been reading up on the history of burlap bags – the forerunner to polypropylene bags.  This post is based on information at NYP Corporation, a wholesaler of burlap bags.  (See “Jute to Burlap.”)

For centuries, the people of India used jute, the plant which burlap is made from, to make rope, paper and handwoven fabrics.

The first mill to mass produce burlap and other jute products was established near Calcutta, India in 1855.  This region is still the main supplier of jute products today.  The mechanical process of spinning jute fibers was first worked out in Dundee, Scotland.  Dundee produced the first power-driven machines for the mill in Calcutta in 1859.

According to the article on NYP Corporation’s website, “By 1869, five mills were operating with 950 looms.  Growth was rapid and, by 1910, 38 companies operating 30,685 looms exported more than a billion yards of cloth and over 450 million bags.”
Photo source: http://www.militarysupplyhouse.com

A sandbagged military position during the American Civil War.

A sandbagged military position during the American Civil War.

Update from Doug at http://www.dailykos.com/story/2009/7/18/754890/-NFTTFill-The-Sandbags!-Edition

Doug has kindly informed us that sandbags can be traced back almost 250 years to the Napoleonic Wars, during which time French troops were issued sandbags for use in the field.

The excellent photo above shows how sandbags were used during the Civil War.

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John Annesley chose earthbags to build the walls for his large shop in the Arizona desert because they will never rot, burn, harbor mold or off-gass noxious chemicals. Additionally they provide good thermal mass for the fly-wheel effect that works so well in this climate. He plastered the walls with a combination of paper fiber, adobe soil and lime. He welded rebar arched roof trusses that support mesh  for a ferrocement roof.


The story of why and how he built this structure is now available to see at earthbagbuilding.com.

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In a thesis written by Bryce Daigle, titled “Earthbag Housing: Structural Behavior and Applicability in Developing Countries,” It was determined that the compressive strength of unplastered earthbag housing specimens meets or exceeds the vertical compressive strength of conventional stud-frame and alternative construction techniques such as straw bale housing technology, using a variety of fill materials, with the greatest strength being observed for soil-filled bags. The weakest specimens tested (the small, granite gravel-filled 9-bag stacks) obtained maximum compressive strengths almost 10 times as great as those typically achieved by conventional stud-frame housing in terms of load per metre of wall length.

It should be noted that the above conclusions regarding earthbag housing are based on the unplastered tests conducted in this thesis. It is possible that plastering of specimens will lead to increased stiffness.

test22Furthermore, the thesis states that with regard to constructability and material availability, earthbag housing is a very attractive construction technique. Soil, of one form or another, is available in virtually all inhabited regions of the world, and polypropylene bags are already manufactured for a variety of purposes in many developing and developed countries. The level of expertise required to assemble an earthbag house is attainable by virtually anyone, regardless of previous construction experience.

Soil-filled earthbag specimens were stronger and stiffer than gravel-filled specimens fabricated with bags of the same size and assembled with an identical stack height. There was little difference in stiffness between specimens filled with topsoil and those filled with a 4:1 ratio of topsoil to masonry sand.

For unplastered specimens, it was found that a folded, pinned closure was sufficient to prevent premature failure due to fill loss through the bag opening. It was also found that taller earthbag stacks led to lower specimen strength and stiffness.

The entire 182 page thesis is available to download as a PDF file at earthbagbuilding.com.

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There is an ongoing debate over the origins of earthbag building — who ‘invented’ it and when.  It is an important point that gets into sticky questions about patent rights of building with earthbags.

Some accounts of military sandbag structures go back over 100 years.  I haven’t seen pictures of these, but a recent Google search turned up lots of images of sandbag (earthbag) structures that were built during World War II and the Korean War.  Most photos were of crude sandbag-reinforced trenches and gun fortifications.  However, I discovered several interesting photos of well-made sandbag buildings that pre-date modern sandbag structures by several decades.

The photo below shows a bunker with straight walls, a door and at least one simple window.  It’s nothing fancy, but it does document how military sandbag structures were used (and lived in) decades ago – in this case, over 50 years ago.

sandbag bunker

Here’s a quote from the news article associated with the photo: “The bunker in which Sgt. Orville Hinck and his comrades lived was made out of old railroad ties and sandbags that would provide some safety from exploding enemy artillery shells.”

Kelly Hart goes into more detail on the history of earthbag building at http://www.earthbagbuilding.com/history.htm.

Photo courtesy of Orville Hinck (from Korean War, 1955)
Photo source: http://www.sedaliademocrat.com/onset?id=1382&template=article.html

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We live in interesting and somewhat precarious times.  No one can say for certain that they are immune from economic collapse, civil disturbance or even war.  With the world’s escalating financial, environmental and political problems lately, anything is possible.

All the many benefits of earthbags are reported on our EarthbagBuilding.com website – low cost, simplicity of construction, durability, and on and on.  But almost no one mentions the bullet resistance of sandbags (earthbags).  As this post explains, it’s a bonus benefit of earthbag building that is often overlooked.

How effective are sandbags for stopping bullets? The Box O’ Truth website performed a test to find out: http://theboxotruth.com/docs/bot7.htm.

Testing bullet resistance of sandbags using boxes of sand.

Testing bullet resistance of sandbags using boxes of sand.

They built boxes out of 2×6 lumber and drywall, and filled them with sand so they could measure bullet penetration.  Four boxes were stacked back-to-back on sawhorses.  But it turns out they didn’t need that many.  Just one box would have been sufficient.

They started out with a .22 LR from a .22 revolver.  It penetrated about 5 inches into the sand.

They continued the test using 9mm Ball, .45 ACP, 5.56mm XM-193 Ball out of a 20″ AR15, 7.62 X 51 from a FAL, a 12 gauge slug, and finally .223 and .308 rifle rounds.

None of the rounds penetrated more than 6”!

And I’m sure the military have done extensive testing on this or they wouldn’t have kept using sandbags for all these years.  I think we can add bullet resistance to the list of earthbag benefits.

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