Durability of Polypropylene Bags

What is the lifespan of poly bags, and will they make durable foundations? From our experience and from what we can gather from other sources, poly bags can last almost indefinitely if kept out of sunlight, and therefore double-bagged foundations appear to be extremely durable. This is important because earthbag foundations are much lower cost than concrete foundations.

One report said 30-year-old polypropylene bags were recovered from a landfill and they were still in good condition. This is approximately how long poly bags have been in existence. We also know from anecdotal evidence that moisture does not seem to adversely affect the poly material even after years of contact with wet soil and natural swings in temperatures, including harsh freeze/thaw cycles.

A Federal Highway Administration (FHWA) study concluded that the half life of polypropylene fabrics in benign environments could be 500 years or more.

[Note: this information is from a GeoMonolith report at GCSwall.com. We would like to find the original FHWA report in order to check the facts. If anyone has time to locate this report, please let us know. You could easily talk me into a free book for your trouble.]

Update: One of our readers who goes by the name Thomas has just won a free earthbag building book. Thomas located the original report we were looking for. Actually, there are four reports that analyze 24 exhumed samples from 12 sites. This government study should provide very compelling evidence about the durability of geosynthetics (poly bags). Thank you Thomas. We’ll get the article and summarize the report here at a later date.

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Cover Shot Chosen for New Earthbag Book

Julien Balmer’s Freeform House at Phangan Earthworks, Thailand

Julien Balmer’s Freeform House at Phangan Earthworks in Koh Phangan, Thailand has been chosen as the cover shot for my upcoming earthbag book. Long time readers may remember Koh Phangan as one of last year’s earthbag workshops.

Hubert Huot and Julien have built some of the most amazing earthbag structures to date and I am very pleased to feature their work on the cover of my book. I would like to take this opportunity to thank Julien publicly for his generosity in freely sharing this photo, and for Hubert and him being gracious hosts at last year’s workshop. You can see many more photos of their projects on their Galleries page.

Julien’s Freeform House is also profiled on our EarthbagBuilding.com Project page. Like no other house I’ve seen, it is seamlessly integrated into the landscape between large boulders. Other interesting features include recycled ship masts as poles, outstanding plaster work and a masterfully crafted wood framed roof that maximizes ventilation in hot climates. Julien and Hubert have another earthbag workshop coming up February 19-20, 2011 and a Permaculture Design Certificate Course March 14-27 that come highly recommended.

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Instructable: How to Build an Earthbag Roundhouse

How to Build an Earthbag Roundhouse

Due to the enormous popularity of my first earthbag instructable, I’ve added a new one about building roundhouses. This is the most comprehensive earthbag roundhouse information published anywhere on the Internet, with step-by-step directions and lots of photos.

“We built this earthbag roundhouse in 2010 as part of an earthbag workshop in Thailand, and finished it later that summer. Roundhouses are perhaps the simplest, fastest, easiest earthbag structure to build. We’re extremely pleased with the results, especially in terms of strength and cost. This is one of the strongest structures I’ve ever worked on in my 30-plus year construction career. The main impression is one of incredible fortresslike strength – massive walls with no sway. I’m sure it could easily withstand a direct hit by a speeding vehicle. This is no exaggeration. There’s been at least one incident where a drunk driver hit an earthbag wall and only chipped the plaster. (The vehicle was totaled.) Earthbags also excel at withstanding floods, hurricanes, tornadoes and earthquakes. Engineered plans are now available for whatever conditions you face. Earthbags are even bullet resistant, as explained in our highly popular blog post where compressed earth withstood 50 cal “BMG” 661 grain Full Metal Jacket rounds. Bullet Resistance of Compressed Earth.

The other key advantage of earthbag is cost. For our roundhouse, we wanted things to look nice, of course, but we didn’t want to spend a fortune. The final cost came out to $11.50/square foot. Most stick-built houses are $100/sq. ft. and up, so this roundhouse demonstrates how anyone can build their own home even on a very tight budget. We used a few basic, low cost methods to class up the roundhouse: rounded window and door openings (free), nice colors (no extra cost), curved bathroom wall and buttress (no extra cost to create curves), exposed wood and thatch roof (dirt cheap), earthen plaster on the interior (really dirt cheap), and lots of beautiful old windows for views, ventilation and to add a sense of spaciousness. In summary, build small — just what you need, use simple shapes, pay with cash, and add on later if needed.

Basic project information:
18’ exterior diameter; 15’ interior diameter; 177 sq. ft. interior floor space; total cost of materials: $2,045, which is about $11.50/square foot

You can read the entire step-by-step article free at Instructables.com.

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Earthbag Eco-village in Beijing

Earthbag Eco-village in Beijing

Earthbag Eco-village in Beijing

Dr. Sunny Cai, an architect and Associate Professor at the University of Science and Technology in Beijing sent me news of his most recent earthbag work. It’s interesting to note his Ph.D. is in Historic Chinese Earth Architecture.

“To be a designer and professor in university for architectural class teaching, I always advocate low carbon emission, less transportation and avoid any extra pollution for our building. These are my main principles for planning a building. Also I expect my students, who will be the architects in the future, will do the same way for their plans.

After the ecovillage of earthbag construction in Uganda, I started to consider how to improve the whole thing to be more effective, feasible and energy saving. I tried to find some natural materials for replacement of modern and polluting ones. The significant discovery is by using inorganic transmit system that is able to provide the warm and cool from the deep earth, and this method can solve most problems of earthbag building that I have to face in northern China. Most earthbag building might be wildly used in suburbs or areas where electricity is quite deficient. Fortunately I found one producer agree to provide this system and relating assistance. Moreover I also experimented with some natural materials which were recorded in Chinese ancient book regarding some traditional way which seems quite suited to my ideals of environmental protection.

The plan in my blog is for an ecological vacation village. All the buildings will be constructed by earthbags, including the buttressed rectangular building.

Generally to say, good part is more and more people notice and identify our effort for ecological event, and bad part is my work still very hard to go ahead because lacking of approving of architectural laws and government’s support! I still am an isolated pioneer in this field in China! Hopefully this situation will be ameliorated in the future.”
Dr. Sunny Cai

Earthbag Eco-village in Beijing
Dr. Sunny Cai’s blog

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Durable Raised Garden Beds

In addition to our focus on earthbag building, occasionally we cover related sustainable building topics. For instance, if you’re going to live lightly on the land in your earthbag home, you’ll want to produce your own healthy food. Today’s post about how to build low cost, durable garden beds is from the Instructables.com website.

Durable Raised Garden Beds

Most gardeners are familiar with Mel Bartholomew’s Square Foot Gardening system. It’s one of the most popular gardening systems in the world. He’s sold over 1 million books (more than any other gardening book). With this method you can grow fives times more plants in a given space with less maintenance. You’ll use less water, fewer seeds, and have healthier plants and fewer insect problems. He says it takes half the labor of typical gardening. You don’t even have to dig down in the soil, because the beds are raised above ground. This means you can grow plants almost anywhere, including areas where the soil is really bad. Instead of trying to fertilize and amend lousy soil over a period of years, you use perfect soil right from the start. Be sure to check out his Square Foot Gardening website for full details. In short, it’s a fantastic system and works great.

But there is one drawback that could be improved. Mr. Bartholomew recommends wood for building the raised beds. He probably does this to keep things as simple as possible. Anyone can go to a building supply center, buy some boards and nail or screw them together. But most wood doesn’t hold up well outside, especially when it’s in direct contact with moist soil. In many cases the wood will rot in a few years and you’ll have to rebuild the beds.

That’s the basis of this Instructable – choose more durable materials for building the raised beds so you don’t have to keep rebuilding your garden.

You can read the full article for free: Durable Raised Garden Beds by Owen Geiger

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Cool Pantries: Storing Food Without Using Power

What’s the difference between a cool pantry and root cellar? Humidity. Root cellars are very practical for storing certain types of produce, and have been a key part of sustainable households for centuries. Root cellars are kept fairly moist in order to best preserve the crops that are stored there. However, the high humidity limits their use since many food items require a dryer environment to avoid spoilage. A cool pantry with low humidity is suitable for storing a wider range of food items.

Kelly Hart and I created a simple, easy to build design to help make cool pantries a standard feature in homes. This design can be added to most new homes or retrofitted to existing houses. The idea of having a large cool storage room next to the kitchen makes so much sense to us that we think all houses should be designed this way. This facility uses no energy to keep things cool and promotes a lifestyle of fewer miles driven, along with a feeling of abundance and security. Imagine millions of homes with this feature and how much energy could be saved.

You can read the full article by buying the February/March 2011 issue of The Owner Builder Magazine.

Note: We will build this cool pantry at our next workshop April1-6 in Thailand. See our Workshops page. And I’ll add the design to Earthbag House Plans soon, so people can incorporate it into their homes right from the start.

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Mortage-free Property

This wonderful idea is from Canadian Dirtbags, one of my favorite earthbag blogs.

“Don’t have the money to buy land? Consider ‘borrowing’ a patch of land before you lock into a mortgage that will have you working to pay it off for who knows how many years.

We met a gentleman last year who has been borrowing land for about forty-five years. Hasn’t owned land since he landed in the U.S., has never paid rent, and has never been without a home. Instead, he approaches a landowner and offers to build a home on their property in return for a five to ten year rent-free lease on the property. At the end of the term, he simply moves on to do it again with the landowner now in receipt of a home they can either live in themselves, rent out, or use for guests.”

You can read all the details on their blog: Canadian Dirtbags

Here’s a rather extensive list of earthbag blogs.
(Please let us know of any others.)

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