by Ann V. Edminster – Pacifica, California
This paper was presented at an Ecopsychology Conference held at Boise State University during April 1996.
This paper focuses on people’s relationship to the built environment. Building is a fundamental human activity, and yet our relationship to the built environment has gone way off course. This is due, in large part, to people’s disconnectedness from the natural process of building, and instead turning over the responsibility for housing themselves to highly industrialized mass building practices. These practices have had catastrophic ecological consequences, are responsible for high rates of homelessness, and their social and psychological costs are devastating and incalculable.
Today I’m going to talk about how strawbale construction facilitates people making their dwellings their own, in various ways, and strengthening their connections to place.
A little over two-and-one-half years ago, I first heard about using straw bales to build with. I was immediately captivated by the idea: here was a material that was completely renewable (in a single growing season), non toxic, plentiful, and cheap. And it actually produced remarkably appealing buildings. It sounded like the ideal building material.
My interest in straw bales sprang primarily from a sense that they offer an environmentally sound, potentially affordable alternative to conventional stick framed houses. But, the more I pursued my research through talking to people and working, hands-on, on strawbale projects, the more I realized that there was an exciting human dimension to this method, as well. This was a building process that contributed to people’s emotional possession of place, to their sense of belonging.
While many wall raisings are now being done under the tutelage of experienced strawbale builders, and there are a good many contractor-built strawbale homes, there are also numerous stories of homeowners successfully building on their own, armed solely with a pamphlet or video for guidance. Strawbale home construction is usually done at least in some part by the ultimate inhabitants themselves. It may be this quality most of all that makes straw bales an appealing building material, one that contributes to that sought after sense of belonging. When one participates in the making of one’s own home, how can it not engender a greater, deeper feeling of ownership than when one does not?
A LITTLE HISTORY
The history of bale construction is not as brief as most people initially suppose. In the cosmic scheme of things, however, it is pretty recent: the first bale structures were built in the late nineteenth century in the Sandhills of Nebraska.
Without going too far out on a limb, it certainly seems safe to venture that strawbale construction is the most significant vernacular building system that has emerged in this country in the last century. This unique stature, in and of itself, suggests that building with straw bales is a process that people “own,” wholly and naturally. It is not a system that was “invented,” and promulgated academically or commercially; it simply arose, spontaneously, from people’s needs, resources, and ingenuity. It is also interesting to note that it is quite different from most other building techniques in that it represents the adoption of a product of another industry, created originally for quite different purposes. Brick, adobe, and dimensional lumber, by contrast, were devised specifically for building. (Michael Reynolds’ Earthship rammed-earth-tire method may be the only other system like strawbale in this respect.)
I’ll start off with a brief review of the building system. Strawbale buildings are most often built on conventional foundations of one sort or another, usually with concrete slab floors and perimeter footings. Because moisture is the biggest threat to the integrity of a strawbale structure, the bale walls are typically built above a curb to raise them above the surrounding grade. Obviously, the extent of this precaution should be in direct proportion to local climatic and microclimatic conditions. Embedded in the perimeter concrete are “imbalers,” steel rebar pins whose ends protrude the height of a bale or somewhat less and on which the first row of bales is skewered. Strawbale walls are assembled much like brick masonry, in running bond fashion; the bales are, in effect, giant, lightweight, scratchy building blocks. Conventional wisdom is to allow a strawbale wall to rise no more than seven courses high unsupported—this makes a wall up to ten feet or so tall, depending on the height of the bales. As the walls go up, lengths of rebar or bamboo are typically spiked through layers of bales to knit them together, forming a sort of thick basketry matrix. Alternative wall stabilization methods include polyester strapping tie-downs and the “Gripple” system, which uses 12-gauge agricultural wire and clamps from the hops growing industry.
Rough wooden window and door frames, called “bucks,” are inserted into the wall as it is being assembled. They are secured to the bales on either side with rebar pins or dowels.
There are two basic approaches to supporting the roof. In the first, which is referred to as load-bearing or “Nebraska style,” the bale walls themselves support the roof. The other approach is to carry roof loads with a structural framework, and use the bale walls as nonstructural infill. There are many variations on these two basic approaches, as well as countless hybrids.
strawbale buildings are almost always covered with a conventional roof frame, usually wooden—sometimes trusses, sometimes rafters. Steel trusses have also been used.
Walls are usually finished, inside and out, with plaster or stucco. Although cement plaster and stucco appear to predominate, there are also numerous examples using mud, lime, and gypsum plaster. Cement stucco on a wire mesh is often used to contribute to the building’s lateral (wind/seismic) load resistance capability. The plaster or stucco wall coatings protect the walls both from surface moisture (rain, e.g.) and from pests; the walls are sealed as wood frame walls are sealed, so insects and rodents cannot penetrate. Plastering, like wall-raising, can be great fun as a group enterprise.
Besides pests, other aspects of strawbale construction about which performance questions frequently arise include vulnerability to decay and fire. Straw, like wood, needs to be protected from both of these natural phenomena. In simplest terms, the strategies for decay- and fire-prevention are the same as for wood-framed walls—again: seal them up so moisture can’t get in, and cover them with fire-resistant coverings, such as stucco. Stuccoed strawbale walls have been tested to withstand fire twice as long as conventional wood framed walls. Practical experience also supports this result: late in 1994 a Southern California fire decimated an entire neighborhood, leaving the only structure unscathed a plastered strawbale garden bench at the home of Ken Haggard and Polly Cooper (architects of the Noland house, the first code approved strawbale building in California).
In addition, strawbale buildings offer superior thermal and acoustic performance, and, according to many fans, a more appealing aesthetic than stick-framed buildings. They also hold the potential for significant environmental benefits, as demonstrated in three different master’s theses. In the first, Joe McCabe established that straw bales have insulating values ranging from R49 to R55. Paul Fritz, using the DOE2 computer simulation model, showed that substantial operating energy savings could be achieved using straw bales instead of wood frame walls. I developed a method for comparing the measurable environmental impacts associated with different building systems—embodied energy, water consumption, and waste production—and found that strawbale systems have the potential for far lower impact than conventional systems.
Further, the vast majority of straw, an agricultural byproduct, is presently burned in the fields. Making productive use of waste straw would lessen air pollution while reducing demand on the timber industry (which most leaders in architecture and construction recognize as a dire necessity).
Finally, the porous bulk of strawbale walls provides such effective acoustic protection that they are being considered for use in freeway walls and have already been used in such applications as school yard boundary fences.
There are numerous qualitative virtues of strawbale construction, as well. It is these, I believe, which make this building system such an effective means of connecting people to the processes of dwelling.
People respond joyously and gleefully to the experience of handling and building with straw. The excitement of participating in a strawbale building project is palpable. Particularly for women, traditionally excluded from the process of creating homes and other buildings, it is a powerful experience. At a barn raising I attended in Sonoma, California, at least half of the participants were women, ranging in age from twenties up to sixties. There was a task for everyone, regardless of age, gender, or ability. Many of the men were white collar workers who had delightedly shed their office garb in favor of “grubbies” for the day’s work.
There is a little of the architect or builder in each of us, and the strawbale wall raising experience is like the ultimate “dress up” or “playing contractor.” Even better, because the results are real—everyone in attendance can claim a piece of the project. This is important in fostering a sense of ownership of or belonging to one’s place in the world. I now have a stake in the little community of Sonoma, and that community garden, in a way I never would have otherwise.
I have a friend, a builder, who contends that ordinary people are quite capable of building for themselves in conventional ways, too—we just don’t know it. What strawbale construction does, perhaps better than any other contemporary building system, is to lure people into using it, building with their own hands—people who would never consider touching a framing square or Skil-Saw. This process, for a variety of reasons, gets us over the hump of disbelief in our own abilities.
Straw is Natural
I believe that one of the reasons people respond so positively to straw as a building material is that it is natural. It is a substance we intuitively understand. We know where it comes from, how it is made. We feel safe and comfortable working with it.
Our innate comprehension of natural materials probably accounts for people’s overwhelming preference, when cost ceases to be the deciding factor, for wood, stone, and tile over sheet vinyl, synthetic carpeting, and even premium products such as Corian. While recognizing that natural resources, too, have environmental costs attached to them, it is important to honor these instincts. Ultimately, we will reduce our impacts on natural systems only if we retreat from our headlong lunge toward ever-higher-technology solutions to all of life’s problems. Lower-tech, less-processed materials, in general, have lower environmental costs. And we like them better.
There are few natural structural materials that are socially acceptable in westernized cultures. Adobe, in the Southwest U.S., is a prized natural construction material, but it is very costly. So is rammed earth. Few people aspire to living in teepees, hogans, or huts made of branches, leaves, skins, and mud. Straw bales, then, are unique as a structural material that is natural, non toxic, environmentally benign, plentiful, widely available, inexpensive, and desirable. Although it has not yet garnered such support in the United States, strawbale construction is viewed by the Canadian government as a sufficiently respectable system that three governmental bodies—the Canadian International Development Agency, the Canada Mortgage and Housing Corporation, and the National Research Council—have expended resources toward strawbale research and demonstration projects.
Besides the straw itself appealing to our basic nature, the shape of the bale is an immediately obvious building block, and the module is “people-friendly.” It is a near perfect marriage between human carrying capacity and large size. Bales weigh 50 to 90 pounds and are easily handled by two people; their size is such that the bales very quickly aggregate into a large assembly. The walls for an entire home are typically raised in a single day, or sometimes two, frequently by an unskilled crew. The tools used are on the same order of delicacy: long handled sledge hammers and large toothed, two foot hay knives are the most common implements.
Rarely is imperfection or irregularity seen as a virtue, but it is patently so with strawbale building. The tolerance of a strawbale wall is measured in inches, not in small fractions. Bulges and hollows are inherent characteristics of the method and in fact add to its beauty, as ridges and drips do to a hand crafted ceramic pot or slubs to a hand woven garment. They are mute and eloquent testimony to the human hands that lovingly shaped the building. This imprecision cannot be underestimated in understanding the appeal of strawbale construction to non-builders.
Also, nearly everyone I have talked to about the manifold virtues of strawbale houses mentions the thick walls. When finished on both sides with plaster or stucco, the walls range from about a foot-and-a-half to two feet thick.
The thick walls are appealing for a variety of reasons, principal among which are the feeling of substance, privacy, enclosure, shelter, and, of course, quiet. They also create the opportunity for variations in the shell of the building, from surface texture and ornament to wall niches. This encourages self-expression which adds the builders’ personal marks to a house in a way that mere “decorating” cannot.
Because bale walls are strongest with fewest penetrations, window and door openings often tend to be relatively small and few in load-bearing strawbale houses. This contributes to a comforting, womblike atmosphere within a strawbale home. However, partial post-and-beam frameworks make it possible to incorporate window walls, as well. The quality of light entering a space from the deep window reveals can also be very beautiful.
Another aspect of strawbale construction that lends itself to individual expression is its amenability to non-rectilinear forms. Curved walls can be made by two methods.
First, individual bales can be made to curve along either longitudinal axis. This is most commonly done by resting one end of the bale on a raised surface such as a beam, slab edge, or another bale; then applying pressure to the middle of the bale, forcing it to bow where it is unsupported between its two ends. This works somewhat better when pressure is applied to the side of the bale without ties than to the one with ties. Bale walls can also be laid up to form curves by rotating each bale slightly with respect to the last. Typically, when this is done, the wedge shaped spaces formed between the bales are stuffed with loose straw (called “chinking”).
Courses of bale walls laid in curves can be “corbeled” so each projects inward somewhat from the one below, to form domes and vaults or coved corners or squinches. This method has been experimented with, as shown in this mockup at Ken Haggard and Polly Cooper’s home in Santa Margarita, California. I don’t know that anyone has yet built a permanent structure this way, however.
Another possibility is to tip each course with respect to the last by inserting wedges between the courses at their outer edges; depending on the thickness of the wedge and the bale dimensions, this produces curved wall sections of varying radii and is another method that can be used to form domes and vaults. This is a vault that used 2×4 wedges with straw stuffed between them, built by Dan Smith & Associates in Berkeley, California in late 1994.
In an experimental dome built by Matts Myhrman at the Black Range Lodge in New Mexico last October, Matts used a cob (earthen) mixture both for chinking and between the 2×4 wedges to angle the walls inward.
At the detail level, as well as at the level of the building envelope, straw bales offer flexibility in creating form. Perhaps most importantly, they can be retied into shorter lengths, so custom bales can be made to fit where needed.
Bales also can be trimmed and sculpted using a hay knife, electric carving knife, hedge trimmer, or chain saw. This makes it possible to bevel edges for splayed window and door reveals, for instance. Niches and recesses are also easily carved into the bales. Extra forms such as benches and wing walls are also easily added.
Even more fundamental decisions about the building configuration can potentially be made spontaneously during the course of building a strawbale house.
As anyone who has ever been involved with a custom home or remodeling project knows, having the ultimate occupant involved in the building process means responding to change. As the building unfolds in three dimensions, it becomes possible to grasp the reality in a way that isn’t possible just from the drawings. This inevitably means some ad hoc redesigning while construction is underway.
With strawbale construction, where the homeowners are often intimately involved in the building process, it makes sense to acknowledge and accommodate this tendency from the outset. And bale building lends itself, in at least one fairly simple way, to this kind of accommodation. Because stacking bales to mock up walls is a rather trivial affair, and because these mocked-up walls are opaque, it would be possible to decide upon the sizes and locations of window and door openings from within the actual building envelope, and with a realistic perspective on the ultimate interior space. Although this is not generally done, its only unique demand on the building process would be adjusting the construction schedule to account for ordering lead time for the doors and windows. This approach might conceivably be extended to placement of interior partitions, as well, if the building were designed with that in mind.
strawbale construction is often touted as an inexpensive building method. This is a statement which bears qualification. Most strawbale houses use straw only in the walls. Since the walls represent only ten to 15 percent of the cost of a house, expectations of dramatic savings solely due to the use of straw bales are misplaced.
That said, I believe that the most significant factor in making a strawbale home more affordable to people than a conventional one is that strawbale construction has a way of getting people over the threshold of intimidation that separates most of us from the building process. This is, above all, a participatory experience. Although there are any number of contractor-built strawbale homes, I would venture to guess that there are relatively few in which the owners, their relatives, and friends, did NOT have a hand in the building process. To a greater or lesser extent, then, the fact that strawbale construction gets people involved with building makes it more affordable, because we are contributing our own labor to the process. Very often, strawbale home owner-builders incorporate salvaged or recycled elements into their homes, too. This can result in further cost savings. All of these homes, from the most humble to the most elegant, include some sweat-equity component and some reused building materials. All the other parts of the house—the foundation; electrical, plumbing, and heating systems; finishes; doors and windows; roof; insulation; finish carpentry; and a host of other details—remain as complex as they are in a frame house, and require the same skills (sometimes even more). But because getting the walls up is so exhilarating, so engaging, usually by the time the reality of the rest of the process sinks in, the owner is committed. There’s no going back. Thus a new builder is born, and another person, or household, or family, gets reconnected to one of the most basic of human activities—creating a home, forging an intimate connection to place. This is ownership in the deepest sense.
Another inescapable part of the strawbale building experience, one that is inseparable from the owner-builder phenomenon, is the aspect of community building. Seldom, if ever, does one build a strawbale home in solitude. Each experience of which I have been a part has been strongly colored by this force. As I described earlier, I now have a connection with the community of Sonoma that I previously did not. Similarly, as I have met and worked side by side with other strawbale enthusiasts, I have forged bonds of common purpose and shared labor with them and their projects. It could be argued that this aspect of strawbale building might be transitory; that, as the method gained acceptance and became widespread, one might find little in common with one’s co workers on a strawbale project, as can be true on a standard construction site. I believe that, ideally, building with straw will be accepted and dispersed precisely because it is a hands on, owner builder method. It will enable more and more people to build—and to have—their own homes. However, examples to date and earlier parallels in our culture and others also suggest that it will remain an activity which at certain stages will involve the cooperation and participation of the wider community. It is today’s equivalent of a barn-raising or quilting bee. Cooperation is an intrinsic part of the strawbale building culture that should be consciously fostered and preserved.
It is certain that there will continue to be those with the means to have others build for them, and they will be the losers in this respect. But the vast majority of the populace cannot afford hired labor to construct their homes; now many can scarcely afford homes at all, let alone professionally built. Therefore, this building process holds the promise to fill a void in the fabric of our communities created by the dominance of mass construction.
Fundamental questions of consuming interest to scientists confronting a new material are, “What are the theoretical limits of this material?” and “What is its best use?” As architects and builders, we apply these questions to straw bales. We are interested in deepening our understanding of this material so that we can use it in the most effective ways. The structural behavior of strawbale walls is one question that has not yet been satisfactorily answered. The Bale Research Advisory Network (BRAN—whose unofficial mandate is to ‘loosen up the bale movement’), is now in the process of developing guidelines for structural testing. The results of this testing will be enormously helpful in advancing the effective use of straw bales in building.
Another one of the perplexing aspects of working with straw is that it is an inherently flexible material and therefore prone to deformation under loading. As a consequence, one of the dominant structural concerns with strawbale buildings is the effect of loading on the outer stucco or plaster shell. If the walls are allowed to deform excessively, the shell can crack and allow moisture to intrude, jeopardizing the integrity of the entire structure. So, somehow, every strawbale structure has to be rendered invulnerable to excessive stresses on the shell. With our currently limited knowledge, this means stiffening the structure to avoid flexure. But ideally, we would devise a wall coating that would accommodate a degree of flexure without cracking. Such a coating has yet to be devised. But there are also other questions about the theoretical limits of the material. Perhaps most significant is, what are the limits in allowing people to build for themselves? How can we make it easier still? Some of these answers will be informed by test results, but others may be needed to inform the tests themselves.
One avenue toward simplification of strawbale construction is to develop systems that are uniform throughout the building walls and roof, instead of necessitating a separate system for each. Forms that are inherently structurally sound, such as domes and vaults, show great promise. Vernacular examples of earthen domes and vaults exist around the globe, many of them still sound after standing for centuries. This is the approach that Dan Smith and Associates has been investigating for the last couple of years. The vault prototype built by DSA, which I showed earlier, was part of an entry to the 7th International Design Competition sponsored by the Japan Design Foundation. The DSA entry proposed this complete strawbale building system as a viable way for even unskilled, low wealth people to create their own homes.
This is just one of many avenues of inquiry being pursued by innovators all over the world.
WHITHER FROM HERE?
A number of issues will have to be resolved for strawbale building to achieve its potential for allowing large numbers of people to truly own their own homes, in psychological and spiritual as well as literal terms. However, the seeds have been sown and there is a growing momentum surrounding this as well as other natural, nurturing building systems. In the next decade I believe we will see great strides made towards more sustainable systems of ownership such as strawbale construction.