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Archive for September, 2009

There’s great, untapped potential for superinsulated earthbag buildings in cold climates. Here’s a way to combine the best features of earthbags and yurts. The basic idea is to combine earthbag walls filled with lightweight insulation such as scoria (lava rock), with a traditional yurt roof frame that’s insulated with perlite or vermiculite.

Yurts (ghers) have been used in Mongolia and other areas for centuries. Traditional yurts are well suited for cold, windy places, in part because the wind just blows around them. They can, however, be made even more comfortable with extra insulation in earthbags.

Scoria is perfect for superinsulated earthbag walls: low cost, all natural, rot proof, fireproof, doesn’t attract pests, lightweight and easy to work with. Scoria is great for building walls since the aggregates tend to lock together and form stable walls. Tie courses together with twine for best results, and then cover walls with canvas.

Yurt roof frames are readily available through numerous suppliers, and fast and easy to assemble. The steel tension cable is strong yet light. They are very resource efficient, using minimal wood, but often lack adequate insulation. I recommend tying bags of lightweight insulation to the bottom of the frame. Perlite and vermiculite would be excellent choices for ceiling insulation since they’re very lightweight.

This design is portable, just like traditional yurts. The entire structure can be disassembled and transported if necessary. This would be a dream structure for places like Minnesota, Canada, Alaska, Siberia and Mongolia because it would be super comfortable, inexpensive, portable, wind resistant, owner built and could be built in many sizes. Add a skylight, rocket stove, small solar panel and composting toilet and then you can laugh at the wind howling by.

Note: you can use recycled bags if available (often farmers have them). You can also order tubes from poly bag suppliers. They make custom sizes. Tubes are faster to fill since you don’t have to stop and tie the ends as often. A 12″ tube (measured when empty) that provides 10″ of insulation when filled would be ideal for many cold climates. Simply tie the tubes to the yurt frame with twine. Use whatever insulation is most practical in your area.

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In addition to many other uses, earthbags also make great privacy walls. Besides being beautiful, privacy walls help block wind and noise, and keep out stray dogs and prying eyes. You can greatly enhance your home using this dirt cheap building technique.

Privacy Wall

Privacy Wall

Protected from excess wind, plants can thrive even in harsh climates like New Mexico. In fact, you can create a mini oasis behind privacy walls with proper care and adequate watering. I refer you to a great little book called Behind Adobe Walls: The Hidden Homes and Gardens of Santa Fe and Taos, by Lisl and Landt Dennis. They document through beautiful photographs of luxurious homes how thick earth walls shade plants in heat of summer and retain heat for nurturing many types of flowers and other plants through cold spells.

Unlike straw bale privacy walls that are susceptible to moisture damage, earthbag privacy walls can withstand the elements much better. They take more time to build, but you can make earthbag walls as moisture resistant as you would like by stabilizing the soil fill material with lime. Alternatively, you could experiment with building privacy walls of scoria, which is highly resistant to moisture damage, and lightweight and easy to work with.

And because earthbags are so versatile, you can combine earthbag privacy walls with planters, benches, arbors, trellises and garden walkways to create magical spaces that are only limited by your imagination.

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Domes are very strong and perhaps the best option for many areas. However, in rainy climates they are prone to leaks. (Domes originated in desert regions, after all.) In high rainfall areas, roofs with overhangs to protect walls are recommended. Roofs need to be very well built with hurricane tie downs. This is the weakest link in the design because roofs are vulnerable to wind damage, so study up on the specialized building techniques available.

Consider something like this Sand Castle house built by Steve Kemble and Carol Escott. Round, hexagonal or octagonal shapes are all good choices because wind will flow around the building. Same idea applies to the roof.

One big consideration is building on grade versus building on piers off the ground. Try to find some high ground and build on grade (or 1’-2’ above), since this will be stronger and less expensive.

Bag fill: The crushed coral/sand mix used on the Sand Castle is a good choice if available locally. Road base is more commonly available and can be stabilized with lime. Road base is the clay/gravel mixture used to build roads. It’s cheap, plentiful and very strong. And with lime added, walls become virtually waterproof and almost as hard as concrete.

One story structures reduce exposure. Design in fast mounting storm resistant window shutters. Keep roof overhangs to a minimum, maybe 24″, to help prevent uplift.

So in summary, a properly designed earthbag structure is the strongest sustainable building system that I know of. The only thing stronger is reinforced concrete, and that’s not sustainable.

I have numerous plans that could be adapted for hurricane and tornado prone regions at Earthbag House Plans.

These plans are available through Dream Green Homes. I modify plans at no extra cost to meet your codes.

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kikumaKikuma Watanabe is an associate professor of architecture at Kochi University of Technology in Japan and is responsible for the design of several wonderful earthbag projects around the world. He collaborated with Akio Inoue (a Japanese professor of philosophy) on designing an eco-village near Lake Victoria in Uganda, and they have helped the Africans build the first model unit of this village.  A detailed account of this project can be seen at earthbagbuilding.com.

Kikuma Watanabe has a refined sense of design that enables him to combine a variety of  forms into intricately balanced works of art. Elongated domes might be connected with vaulted corridors and intersecting circular forms that create fascinating patterns. These forms are often rooted in the local culture with unique features, such as raised thatched cupolas.

uganda28

Above is one of the nearly finished units of the Uganda Eco-village.

jordan3

In Jordan, he designed a cultural center for the Al-Jawasreh Society that has three architectural components: Jordan’s traditional stone building, modern reinforced concrete, and earthbag domes. As with most of his designs, this one integrates the building forms intimately with the landscape to create a unified whole.

iseger8

Above is the plan of a model unit in the ISEGERO village, also being built in Uganda. The pink circle is the model dome that is being built there.  After the model dome is completed, it will be used for a meditation room. There is a small earthbag house with bedroom, shower room, and toilet.

mandala3

Kikuma Watanabe has also desiged a couple of Mandala Villages for India and Afghanistan that demonstrate how he interweaves functionality with sublime design. When attempting to assist disaster-stricken areas, local people were very pleased with village planning that was shaped with mandalas. These plans may assist in healing the traumatized people.

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