Earthbag Building_ Why We Build With Earthbags

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Why We Build with Earthbagsby Kaki Hunter and Doni Kiffmeyer

from www.thelaststrawblog.org

We live in the heart ofthe great Southwestern

United States, surrounded by examples ofone-thousand-year-old ruins left behind by the

ancient civilizations ofthe Anasazi, Hohokam,

Pueblo and many others. It was these original

natural builders that inspired us to consider

building with earth as a way to create beautiful,

low-impact, energy-efficient housing that has

endured the test oftime to this day.

We started by teaching ourselves how to make

adobe bricks, the most common earthbuilding

technique native to the U.S. Making adobe bricks turned out to be a lengthyprocess that involved

mixing the mud, pouring it into forms, lifting the forms, and then turning the blocks over the next

several days to facilitate even curing. The blocks then had to be stacked and protected until ready

for use. Manufacturing the adobes required a considerable amount ofspace for both the pouring

process, as well as for storage ofthe dirt needed to make them, and then the storage ofthe adobe

bricks themselves until they were ready for building. We live right in the heart ofa small town,

which made this process a little tight.

The dirt for adobe block and most other forms ofearthen architecture require a specific ratio ofclay to sand, ideally about 25 to 30 percent clay to 75 to 70 percent well-graded sand. In some

cases, a stabilizing agent may be added to an earthen soil to increase its compressive strength and

make it resistant to the affects ofwater. Some earth building techniques like cob require copious

amounts ofstraw fiber added to the mix. In most cases, adobe brick also benefits fromthe

addition ofstraw or some other kind ofnatural fiber.

After our initial foray into homemade adobes,

we read about the work ofinternational award-

winning architect Nader Khalili. Nader is an

Iranian-born architect who abandoned asuccessful career designing skyscrapers to

follow his heart, which led him to create an

innovative sandbag/superadobe/earthbag

architecture as a means ofproviding low-tech,

enduring affordable housing. Inspired by the

ingenious monolithic adobe buildings ofhis

homeland ofIran, Nader conceived the idea ofbuilding domed and vaulted structures with.bags

ofearth. We took a one-day workshop withNader and we were hooked! We returned home

excited to build our first earthbag-wall project, a privacy wall opposite the busy baseball field


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Wall plastering options range fromthick natural earthen plaster applied directly over the surface of

the bags (yes, it sticks!) or, for additional protection, lime plaster canbe applied over an earthen

plaster. Cement/lime based plasters performwell when the earthbags are filled with a stable, well-

draining sandy soil and applied over stucco mesh (chicken wire). Plasters can be applied by hand

or sprayed on with a pressurized plaster sprayer for a unique contoured effect that accents the

shape ofthe bags or tubes.

Earthbag Architecture can be designed to suit a wide variety ofclimates. Since the wovenpolypropylene bags are virtually rot proof, earthbags are an excellent choice for underground

structures: root cellars, storm shelters, bermed homes and greenhouses. In climates where wood

is scarce, whole houses can be built exclusively with earthbags including the foundation and roof,

as is the case for corbelled earthbag domes. Earthbags also combine well with other natural

building materials that can be combined together to create hybrid structures. Straw bales can be

interlocked with earthbags to build sturdy arch entryways or to add thermal mass to the interior

wall ofan attached sunroom. Or we may choose to use earthbags for the sunken first level ofa

structure and then switch to strawbale, post-and-beam, cob or adobe brick for the rest ofthe wall

above grade to make use ofan available resource or add aesthetic variety.

Insulation strategies for earthbag walls offer a

variety ofoptions. Narrow tubes provide a sturdy

load-bearing wall with plenty ofthermal mass,

while straw bales secured to the exterior ofthe

wall provide ample insulation. Now, we have mega

mass coupled with mega insulation to provide the

best use ofboth ofthese materials in one building.

Another way to add interior mass is to build our

interior walls with earthbags and our exterior walls

with straw bales alone. Another approach we have

experimented with is mixing a percentage of3/4-

inch pumice to a quality rammed earth soil that

captures air spaces within the earthbag itself. A

50/50 mix ofsuitable earth and pumice make the

bags one third lighter than their normal all dirt

weight yet still makes a nice hard compacted earthbag.

Building codes

The earthbagbuilding system has been extensively tested by Nader Khalili in conjunction with the

ICBO (International Conference ofBuilding Inspectors) and the Hesperia Building Department in

Hesperia, California, at the California Institute ofEarth Art and Architecture for earthquake

resilience, loadbearing, and shear strength stability, all ofwhich were proven to far exceed

conventional code standard acceptance.

Resources

Sources for bags and tubes can be found on the Internet under woven polypropylene feedbags.

Our favorite U.S. supplier for both pillow-pack and gusseted misprint bags is www.innpack.com,


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toll-free 800.622.3695 in Tennessee. Typical prices for 50-lb misprints are approximately $.17

each (USD), and 100-lb bags are $.25 each (USD). Both come inbales of1,000 bags. Smaller

quantities for bags and tubes are available froma Kansas City, Missouri, source

www.centralbagcompany.com 816.471.0388. Ask for Chris Klimek for prices and selection.

Also try 800.521.1414 www.fultonpacific.com.

For step-by-step nitpicking details about building with earthbags, check out our bookEarthbag

Building, the Tools Tricks andTechniques by Kaki Hunter and Donald Kiffmeyer, NewSociety Publishers, 2004. Or call us at 435.259.8378, or visit our web sitewww.okokok.org.

Donald Kiffmeyer and Kaki Hunter have been involved in alternative construction since 1993,

specializing in affordable, low impact and natural building methods. Inspired by the work of

visionary architect Nader Khalili, the grandfather ofSandbag/ Superadobe/Earthbag architecture,

they wrote a screenplay entitled "Honey's House," a film about truth, justice and affordable

housing. From these innocent beginnings, they were launched into the alternative building

movement where they were encouraged to share their combined innovations to establish the

Flexible Form Rammed Earth technique. Together they co-authored the book Earthbag Building,

the Tools, Tricks and Techniques by New Society Publishers. They live in Moab, Utah, wherethey continue to focus on the research and development offun, quick, simple and solid natural and

alternative building techniques that are inspired by this fabulous planet.

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Earthbag Building_ Why We Build With Earthbags