An introduction to building houses with straw bales.
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A venerable Japanese rice farmer once said, "The ultimate goal of farming is not the growing of crops, but the cultivation and perfection of human beings". This was a profound thought for me, who as a permaculture designer valued so much the practical and functional aspects of my labors. Then it dawned on me that just as individuals can only find spiritual balance within themselves by resolving internal conflicts before resolving external conflicts, so too can we only find environmental harmony in our settlements by turning inward to fulfill our physical needs before turning outward. Instead of depending on remote sites and resources for water, food, shelter, income, education, and medical care, we should first turn inward to what we already have available on site and all of the potential uses we can design into our settlements.
If you had asked me a year ago whether or not I could turn a field of grass into comfortable and safe home I would have chuckled and asked if you knew the tale of the three little pigs. Today I live in a straw bale house built from a pasture of klein grass grown less than a mile away. If you had asked me if it was possible to obtain drinking water from anywhere else than a well or a municipal water purification plant I would have looked to the sky and only shook my head. Now I look to the sky with eager anticipation for the drops of rain which we harvest off of our roof in a ferro-cement cistern, and when we are done using that water for drinking and washing we will harvest it yet again in the form of food and water for our fruit trees!
At the Cross Timbers Permaculture Institute of north central Texas (my home and place of work), we decided last August to build a straw bale residence to better accommodate our staff and growing number of apprentices. We felt that the emphasis we placed on creating a natural garden to grow our foods applied equally to the homes in which we grow ourselves. Consequently we have combined three designs which we hope will merge into a well centered, natural dwelling - a straw bale house, a ferro- cement cistern to collect rain water from the roof, and a pumice-wick system to aerate and harvest our toilet and sink's "black water".
Natural building like natural farming encompasses the ethics of permaculture - care of the earth, care of all species, and the return of excess to the land. It calls for a greater awareness of the materials we build with, urging that they be indigenous, and locally available. Building materials should also be human friendly and non-toxic, and our techniques of construction should be sound and enduring. A designer should not rely on over-manufactured products which are high in toxics and energy inputs. Building naturally involves the intelligent siting and orientation of our settlements and requires that they be designed into the landscape rather than super-imposed on it. Natural building is also less expensive, better for us, and more fun!
We find the origin of straw bale construction tucked away in a chapter of our own North American history. This building system was begun by settlers in the Sand Hills of Nebraska during the late 1800's, coinciding with the advent of the horse and steam powered baler. The Nebraskan settlers used bales of prairie grasses (stacked much like a mason lays bricks) for their walls and covered them inside and out with an adobe plaster. It was advantageous then to use grass as a building material because timber was not abundantly available and straw bale homes could be built larger and more efficiently than sod homes. These wall systems were structurally sound and supported the entire weight of the roof. We now refer to straw bale homes with load bearing walls as "Nebraska-style" homes. Some of the original Nebraska-style structures are still standing, now nearly one hundred years old.
Straw bale construction faded from popularity between the 1950's and 1980's probably because of the increased availability of massed-produced construction materials. Today, however, the US is experiencing a natural building renaissance and the revival of straw bale construction is evident in the states of New Mexico, Arizona, Texas and California. This renaissance is quite likely due to today's prohibitively high cost of building and our waxing interest in more ecologically sound homes and gardens. With the abundance of information now available on building with straw bales, the straw bale house is one of the most affordable and feasible options for the owner-builder.
Our institute's straw bale house for example - we have managed to build a 560 square foot residence for approximately $2,500 dollars or $4.50 per square foot! We relied on our own labor, and salvaged most of our materials, which demonstrate that if you have the will to do so, affordable housing has not escaped our generation. By using straw bales in our walls instead of timber studs and sheet rock we will also save substantial amounts of energy on heating and cooling due to the bale wall's high insulative properties (R42 for straw vs. R24 for timber and sheet rock). For the owner-builder there is hardly a more elegant solution. If you would like a definitive reference on straw bale construction, you may want to acquire The Straw Bale House, from The Canelo Project (a non-profit organization) in Elgin, Arizona at 520-455- 5548.
The wonderful thing about a permaculture site is that everything is more than it seems. For instance, the roof of our straw bale house is not just a roof to keep the rain off of our heads, but also a collector to catch and deliver the rain into a ferro-cement water cistern. Rather than spend the effort and money to drain the rain water off of our land and then import water back into our homes from wells or far away treatment plants, a permaculture settlement holds onto rain water and uses it as many times as possible before allowing it off site. Using rain water as drinking water is usually its first and most valuable use, and though it is difficult for many people to believe drinking rain water is safe, with a few precautions it can be the purest water we ever encounter. Rain water is also excellent for watering gardens as it has a lower pH than ground water and better enables the uptake of minerals, especially phosphorous, in plants.
At Cross Timbers we have built two cylindrical, domed cisterns made from iron re-mesh, re-bar, stucco lathe, and masonry cement - the common name for this type of cistern is a "ferro-cement" cistern. For our 650 square foot roof, and annual 26 inches of rainfall we have built a 6,500 gallon cistern. It needs to be spacious enough to hold all of our spring and fall rains and last through our drier winters and summers. To keep the water clean for drinking we divert the initial wash-off from the roof which may be contaminated with bird droppings into our gardens. The cistern is also opaque which keeps sunlight out and prevents the growth of algae. For added precaution, many folks filter their cistern water at the tap with a standard water purifier.
When we are done using our rain water for drinking, washing and flushing toilets we are challenged to discover even more uses for it. A good permaculture designer views this load of moisture and nutrients as a boon not a bane and sets about incorporating it into a sound, and useful food producing scheme. One of the most effective and least expensive designs I have come across to date is Tom Watson's pumice-wick system - essentially a canal filled with volcanic pumice rock and covered with soil. Just as the wick of a kerosene lamp pulls kerosene upward against the flow of gravity, so too does the porous pumice rock draw the water out and over the rocks' surfaces so the nutrients can be devoured by millions of aerobic soil organisms and taken up by the roots of plants and trees.
There are two important distinctions between the Watson-wick system and conventional septic systems. These distinctions also illustrate the principles which make it so successful. First, the pumice-wick does not depend on an anaerobic septic tank which will often clog up with waxy soap residues and fibrous solids, but instead creates and relies upon a very aerobic substrate, the pumice-wick, where soil organisms are much more active and effective in breaking down nutrients and pathogens. Another distinction relates to the roots of trees and bushes which are naturally drawn to and work their way into the "leaky" dispersion pipes of a conventional leach field. Where the activity of these root systems hinder the performance of a conventional leach field and often cause it to back up or rupture, the roots of plants play a key role in the pumice-wick system, taking up dissolved nutrients and water, and turning them into fruit and/or transpired moisture which may one day rain back down upon us!
Tom Watson's wick system takes what we would normally consider a very smelly mess and turns it instead into the richest garden bed in our landscape. He has built 75 of these systems, the oldest of which is 16 years old and still functioning well. Though root crops are not recommended for growing over a wick system, just about every other type of plant can be grown and will most likely flourish.
All of these designs, the straw bale house, ferro-cement cistern and pumice-wick system, illustrate how we can center ourselves in our landscape by connecting and harvesting the natural flows of energy through and around us. At Cross Timbers we have found that connecting ourselves to natural systems has given us more than just an efficient homestead, it has given us a sense of belonging and contentment. The ultimate goal of being spiritually and physically centered in the landscape is both the cultivation of humans and their settlements - our landscapes are but the reflection of our souls.
Kirby Fry is the Program Coordinator for Cross Timbers Permaculture Institute. Route 1, Box 210-A, Glen Rose, Texas, 76043 USA.
This article was published in New Renaissance magazine Vol. 6, No. 2