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Archive for May, 2010

We often get questions about where in the U.S. it is possible to build a home without some authority looking over your back and telling you what can and can’t be done. This is especially pertinent to earthbag building since as yet there are no codes that directly apply to this method, meaning that it may be difficult to convince the authorities that it is a safe and sensible thing to do.

I scanned through a new e-book titled “No Building Codes: A Guide to States with No Building Codes”, written by Terry Herb,  to see what he has to say. Most states do have mandatory building codes, but there are still 15 states where the existence of codes is a matter of local jurisdiction. Often it is the larger cities that opt for control of building practice, while the the more rural areas are freer. This is true in Alabama, Arkansas, Hawaii, Michigan, Missouri, North Dakota, South Dakota, and Wyoming.

Some states have just a few counties that have yet to establish code requirements. In Arizona there is only one such county (Greenlee); in California there are three (Mendocino, Humbolt, and Nevada) that have adopted the liberal “Limited Density Rural Dwellings” program; Colorado has 15 open counties (including Saguache county where I live); Iowa has eight free counties; Mississippi is mostly free, except for coastal areas where wind and flood codes are enforced.

Special cases are Tennessee, which is now in transition from having no codes to having mandatory control, and Texas, which does have state codes, but enforcement seems to be very lax. Of course the situation is always changing, so it behooves anyone planning to move to a code-free region to find out specifically what the situation is there.

The book that provided this information contains a wealth of other related advise and data that is well worth the price of the book, and since it is an e-book it can easily be kept up to date.

Since I have lived in a code-free county for many years, I have witnessed the effect that this has had on the type of building being done. One might think that with this freedom would come much sloppy and irresponsible construction, and there is certainly some of this…but not much. Most people want to live in a safe, durable home that will hold its value over time, so most building is just as carefully researched and executed as in areas with codes. The main difference is that there is greater diversity in styles and materials choices, with many people opting for more sustainable and natural approaches to building.

Where I live you can easily find homes built with strawbales, earthbags, adobe, cordwood, rammed earth, and recycled materials. It actually seems that people here are being more responsible, since they are actively seeking to live more sustainably. This attitude is slowing moving more into the mainstream; California is the first state that has actually adopted new green building codes.

I lived in Mexico for many years, and building codes are virtually unknown there. They don’t really need them because building practice is so standardized that the same methods are in use from one end of the country to the other. That cultural uniformity assures that most buildings are actually built to high seismic standards, with reinforced concrete bond beams and columns and masonry infill. Nobody has fire insurance because their buildings will not burn. Obviously building codes do not necessary make for safer buildings.

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Using earthbags for interior walls would take up too much space and so they’re generally not recommended for this purpose. Thinner interior walls are more efficient. The easiest solution is to frame interior walls with 2x4s or, for plumbing walls, 2x6s.

But there are more sustainable alternatives. On some of my plans I use adobe, CEBs, recycled brick or stone around wood stoves for thermal mass. (These materials retain the heat and gradually radiant it back into the house.)

You could also do slipform straw clay (also called light straw clay). I like this method because it avoids sheetrock and the associated taping and texturing, and enables the use of earthen plaster throughout the home. The basic process involves building a recycled or sustainably harvested wood-framed wall 24″ on center, drilling holes and adding saplings through the center of studs, screwing 24″ wide strips of plywood to each side, then stuffing with light straw clay (straw covered with a thin coating of clay slip). Do one course at a time and then move forms up the wall after it has set up. Plaster the walls after drying. This method creates soundproofing between rooms and doesn’t offgass toxic fumes like manmade materials.

Tie interior walls into exterior earthbag walls for strength and rigidity. There are numerous attachment methods, including burying wood blocking in earthbag walls, and using sheet metal anchors.

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Do earthbags really become hard as rock or is this exaggeration? I did a little experiment on the roundhouse we’re currently building to find out.

The answer depends primarily on the choice of fill material and the degree of compaction. The moisture content and curing process also play a role. We used road base – the material used under roads in many parts of the world – moistened slightly and tamped solid. The video shows the result after about one or two weeks of drying.

Note the ringing ‘ching-ching’ sound when I tap the earthbags with a putty knife. It almost sounds like I’m hitting stone. I tap a compressed earth block (CEB) for comparison. CEBs contain about 6% cement and are rammed in a press at high pressure, so you expect them to be harder. But in reality they’re fairly similar as you can hear for yourself. In both examples, densely compacting correct soil mixtures create very strong building materials. They begin to approach the strength of stone at a fraction of the cost and labor.

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Many people want to know the lowest cost way of building. Here’s a short comparison of costs to build an earthbag house using ‘free’ options versus buying the building materials:
hand dig soil on site = free versus deliver soil $200
gather materials and make thatch panels = free versus buy thatch panels $100
hand sift soil for plaster = free versus buying it already pulverized and screened $50
(You could itemize all building costs in a spreadsheet and evaluate various scenarios.)

This shows how you can save money if you want, but at what cost? Do you want to dig for two or three weeks to save $200? Possibly. But maybe your time could be spent more efficiently doing something else. In this example, at 14 days of labor, that’s about $1.79/hour for your time digging soil by hand. (8 hours per day x 14 days = 112 total hours divided into $200 = $1.79/hour.) This includes soil to raise the building site and for the earthbags.

The same is true with thatch. For example, we roofed our roundhouse in one day using $100 of pre-made thatch panels. I can’t even guess how long it would take to do it ourselves from scratch.

Now, I’m not saying to buy everything. I’m just trying to help people understand the options. For our project, we’ve decided to buy these materials because our time (in the case of buying versus digging soil by hand) is worth more than $1.79/hour. In other words, I can do enjoyable, rewarding work and make more than $1.79/hour. I also enjoy natural building, so I’m not going to contract out all the work. But it may make sense to hire someone to fill and carry buckets. There are lots of options and everyone needs to find the right balance that works for them. You may find it advantageous to spend $2,000 and finish your small earthbag house in one month instead of three, and that the least expensive approach is not necessarily the most efficient or best choice for you.

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My Favorite Slider

My Favorite Slider

Here’s a drawing of my favorite earthbag slider that makes it easy to place bags on the wall without getting hooked on the barbed wire. If you want to make one, start out by cutting a sheet of 1/16th thick steel about 13 inches wide by 16” long. Tack weld a piece of 1” by 1-1/4” angle iron on one end for a grip and then weld the back edge. Radius the front corners 2” or so. Grind off sharp edges, remove any rust with sandpaper and then spray paint to protect the metal. Recoat after each project since these sliders really take a beating. And don’t skimp on the steel thickness or the barbed wire will quickly destroy it. Typical galvanized sheet metal is inadequate.

Related: My Favorite Tamper

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Rounded Corners on Earthbags

Rounded Corners on Earthbags

Square corners and tunnel-like window and door openings just don’t look right to me on natural homes. Gently curved openings and corners are much more elegant. Rounded openings have numerous advantages. Around windows, they allow more light into the home and improve the view. And they add a little extra space around doors, making it easier to pass through.

This look is easy to obtain by pinning the bottom of bags. Pull each corner of the bag to the center and pin in place with a nail. Place the bottom of the bag against the rough frame. These rounded corners can be shaped for uniformity with a board, tamper or small sledge hammer before the soil dries.

Rounded Corners on Earthbags

Rounded Corners on Earthbags

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Earthbag Dojo

I just met Disa and Rey at my latest earthbag workshop. I was really impressed with their dojo design and wanted others to see it.

The Dojo and Wellness Center design is an adaptation of Cal-Earth’s eco dome. Our dojo will be built first at the center, and gradually we will build our living quarters around it. Our dome will be much bigger than Cal Earth’s and will not support an earthbag roof, so we are thinking to construct a geodesic dome roof covered with lime plaster or flying concrete.

We have a sea view so we would like a second floor. The walls are 4m high and the top of the dome is another 4m. The kitchen will be outside, and the toilets and shower separate. The toilets will be solar composting and all grey water will be re-cycled. We also aim to make use of wind, solar and wave energy available to us.

Our land will be located on Panglao Island, Bohol, Philippines. We hope to secure the land and start building in 6 months to a year’s time. We will be running workshops and practicing our skills and theories on 5 small pixie dome houses in the ‘garden’. Anyone wishing to see our progress in real time or contact us directly should join our Facebook site Rey and Disa’s Earthbag Dojo page.

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