J - Technical Series

Center for Resourceful Building Technology

EO. Box 100 Missoula, *Montana 59806 * (4 0 6) 5 4 9-7678

Strawba les as a Building

Element

October 1995

Center for A Resourceful 141 Technology - Building

Fosten'ng Efficimt R e s m Use.

The Center for Resourceful Building Technology

The Center for Resourceful Building Tech nology (CRBT) is a nonprofit organization whose purpose is to educate the public on a variety of issues relating to housing and the environment, with particular emphasis on innovative building materials and technologies which place less stress on regional and global ecosystems.

CRBT strives to identify and encourage the use of resource efficient building materials and design elements that exemplify:

efficient use of limited resources demonstrated recyclability or reusability Energy efficiency in manufacture and use

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Introduction .................................................... 5 Historical Use of Straw as a Building Element ... 8 Utilization of Straw ........................................ 10 Environmental Concerns ................................ 11 Building with Straw Bales .............................. 13 Straw Varieties ............................................................................ 13 Bale Density ................................................................................ 13 Moisture Content ........................................................................ 14 Sizes and Weights ....................................................................... 15 Planning With Bales .................................................................... 15 Custom Bales .............................................................................. 16 Orientation of Bales .................................................................... 17 Advantages of Strawbale Building ................. 18 Aesthetics ................................................................................... 18 Labor ........................................................................................... 18 Cost-efficiency ............................................................................. 18 Insulation and Soundproofing ..................................................... 21 Pest Resistance ............................................................................ 22 Seismic Performance ..................................................................... 22 Disadvantages of Strawbale Construction ....... 23 Unfamiliarity ............................................................................... 23 Lack of Testing ............................................................................ 23 Reduction In Floor Space ............................................................. 24 Potential for Complications .......................................................... 24 Extensive Use of Cement and Steel .............................................. 25 Difficulty in Financing ................................................................. 26 Bale Wall Construction ................................... 27 Bales as lnfill within Structural Systems ......................................... 27 Use of the Bale as a Load-bearing Element .................................. 28 Foundations for Straw Bale Structures ............ 32 Types of Foundations .................................................................. 32 Finishing Bale Walls ....................................... 34 Roofing ......................................................... 39 Code Considerations ...................................... 40 Testing Data .................................................. 41 Individual Bales ........................................................................... 41 Wall Panels ................................................................................. 41 Strawbale Building Resources ......................... 46

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Introduction Alternative methods and materials for building are

of increasing interest to Americans. Many people are frustrated by the high price of conventional houses and seek more affordable options. Increasingly too, Ameri- cans are becoming aware that the demand for buildings and the materials to build them takes a heavy toll on the environment. People seeking affordable and/or environ- mentally responsible building methods have created a resurgence of interest in the use of indigenous materials.

Both the financial and the environmental costs of construction can be reduced by using minimally pro- cessed materials native to the building area. Most savings are gained by avoiding the expenditure of en- ergy that would ordinarily be consumed in importing and processing the material. Some examples of present- day indigenous building methods include: strawbale construction, rammed earth, cordwood masonry, cob or bourrine (using clay and straw), adobe, stonework, and the use of salvaged materials and locally available "waste" products.

In general, indigenous building methods allow owners to be involved in the construction process, even if they have little prior building experience. Relatively simple techniques allow owner-builders to save on labor costs by supplementing the labor time of construction professionals with their own or other low-cost unskilled labor. For these reasons, many people are eager to learn more about methods such as strawbale building and seek to determine whether these methods will work for them. This paper has been written with the intent of providing enough information to enable the reader to

determine whether the use of strawbales as a building element is feasible for his or her particular project. This is not a "how-to" book. The booklet contains historical accounts of methods that have been used for building, but these descriptions are not prescriptive guidelines. All of the information presented here must be interpreted by the builder with care and forethought if it is to be incorporated into building design or construction.

Over the past four years interest in strawbale construction has increased dramatically. This surge of interest has been accompanied by considerable hyper- bole, incomplete and misleading media coverage, and the sale of misinformation. People considering building with strawbales should beware of over-enthusiastic claims, and seek an honest assessment of the technology.

Agricultural fibers, including straw, have a largely untapped potential as resource efficient construction materials. For example, straw can be used to manufac- ture sheet stock similar to particleboard. Current testing shows that straw may be a suitable fiber source for fiber cement composite building materials. Straw also finds applications as insulation, both in structural insulated panels and in strawbale block walls. Although straw has been utilized in construction for centuries, little formal monitoring of its performance has been done, and few standards for straw construction exist. As straw-based building products become more popular and an increas- ing number of companies undertake commercial production of straw-based structures, testing and certifi- cation are becoming increasingly important.

At this time, the long-term performance of strawbales as a building element is incompletely under- stood and engineering data are largely unavailable. Standards and generally accepted practices with build- ing code definitions are just beginning to come into

existence. CRBT seeks to convey that strawbale building and related technologies can be used to create structures that are both resource efficient and well engineered. We also seek to encourage further research into the establishment and application of engineering guidelines for strawbale building.

Purpose This technical paper is designed to familiarize code

officials, architects and potential builders with the tech nology, materials, methods, and considerations involved in strawbale building. It is not meant to be a compre- hensive textbook on the subject, nor is it a how-to guide. While the existence of 90-year-old strawbale structures demonstrates that the use of bales as durable building elements is a viable concept, at the same time the potential for construction of unstable and dangerous strawbale structures is very real.

At this time, CRBT believes that further engineering tests and development of guidelines are needed before builders and architects can comfortably specify bales as primary load-bearing elements in residential structures. Until that time bales should be used cautiously, with measures that ensure the structural integrity of the building. The practice of using bales as insulative infill in structural wall frameworks will also benefit from more rigorous testing and clearer description of the limitations and characteristics of strawbales as a building element.

The Center for Resourceful Building Tech- nology accepts no liability for design or application decisions made by owners, builders, architects or others who have read this publica- tion. We urge individuals building with straw bales to learn and practice safe construction techniques, and to design and build according to accepted principles of structural engineering.

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Historical Use of Straw as a Building Element

Straw, grasses and reeds were probably the very first materials used in the intentional construction of human shelter. Straw-like materials are widely available, easy to harvest and transport, insulative and adaptable to a variety of uses. Historical uses of straw in construc- tion are widespread and well documented. Straw or reed thatching provides durable roofing for millions of homes throughout the world, in a wide range of climatic conditions. Additionally, straw is used as fiber reinforce- ment in earth building techniques practiced throughout the world, such as adobe, cob, strawday and bourrine construction. In an old European technique called leichtenbau, the major wall component is the straw itself, cemented with a light clay coating and rammed into wall forms.

In the United States, the first use of baled prairie hay or straw as a primary building element echoed a common practice of Native American plains tribes such as the Wichita and Caddo that used indigenous supplies of coarse grass or straw for houses. The use of strawbale buildings by European settlers in the Great Plains area of the United States also drew inspiration from centuries-old European building methods.

Strawbale building in the United States evolved during the mid-to-late 1800s. Early European settlers in the Nebraska Sand Hills used straw bales to construct buildings when they encountered an area with few trees, where familiar wood framing was relatively UP available. The strawbale buildings that developed in this sandy-soiled area were probably an adaptation of the sod houses used elsewhere on the plains. Walls of baled

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straw or prairie grass served structurally as support for the roof and served double duty as insulation, similar to the way that blocks of earth and grass roots supported the roofs of sod houses. While the sod and bale houses built by the settlers relied upon conventional roof framing, the overall use of wood was substantially less in these structures than in log and other wooden buildings.

There are strawbale buildings in Nebraska and the adjacent area of Wyoming still standing and in use after 50-1 00 years. Owners of these historic structures claim good thermal efficiency and no pest problems. Some of these buildings are two stories high, and others even used strawbales for basement walls. The existing ex- amples of strawbale construction feature a number of innovative solutions to the construction challenges of their particular times and places.

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Utilization of Straw

Straw is a byproduct of grain production. Grain growers have several options for treatment of this byproduct once the grain has been harvested. Straw may be left in the field to be plowed back into the soil. Often straw stubble is burned in the field to clear the land for a new crop, though air quality regulations now restrict or ban this activity in many areas. A third option for the farmer is to cut, bale and sell the straw. Baled straw can be used as animal bedding, as mulch, for erosion control, as a fiber for textiles and paper making, for the manufacture of building materials, or as a build- ing block.

As air quality regulations turn more farmers from burning to baling, building straw should become even more plentiful than it already is-particularly in heavily cultivated areas. As an example, in one county of east- ern Washington state, it was estimated that over 18,000 acres of straw crops were available for bale production within a 25 mile radius of the city center of Odessa, WA. The amount of straw was estimated at 10,000 pounds per acre (Odessa Chamber of Commerce). In this case labor and fuel costs are judged prohibitive to turning the stubble under. so these fields of straw are usually burned following grain harvest. The financial potential of utiliz- ing this waste resource in manufacturing and building could provide millions of gross dollars per grain-growing county.

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Environmental Concerns

A complete report on the environmental impacts of the use of straw bales for building would have to involve a comprehensive investigation of the energy used in, and pollution and soil depletion caused by, cultivation, harvesting, baling, storage, transportation, processing, placement, and eventual disposal of straw used in build- ing. The other materials combined with straw bales in construction would require similar evaluation. A com- parison of this total to the consumption caused by a building composed entirely of more conventiona build- ing materials such as steel, wood, and concrete would then establish the relative embodied energy and re- source efficiency of strawbale walls.

Using baled straw for building has some environ- mentally positive aspects. It prevents the environmental impacts of the most common disposal method of dealing with this ”waste” product - burning. Carbon dioxide emissions from burning are globally significant and particulate emissions and smoke are detrimental to local air quality.

Straw should not be viewed as a building material without an environmental impact, however. The vast majority of straw available in North America is the prod- uct of industrial agriculture with its very large inputs of fossil fuels, pesticides and fertilizers. These represent a nowrenewable fossil fuel subsidy of what might other- wise be a “renewable” product derived from photosynthetic processes and renewable resources.

Another potential environmental disadvantage of straw harvest is eventual depletion of the soil fostered by continued removal of large amounts of organic matter. We do not at this time have any quantitative studies of this potential, but do consider it to be a valid concern.

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Author and farmer Wendell Berry said that, in his experi- ence, straw could "not be taken every year. There is a threshold of humus content necessary to the health of the soil, below which continuous tillage will eventually take you" (Personal conversation, 1994). There is a danger in operating an "agricultural mine" rather than a "farm". While we cannot, in this limited paper. give a prescription of how much straw can be harvested over the long term in various regions and situations, it would not be prudent to assume that all or even most of the straw produced annually in America could be removed from the field each year without a detrimental effect on future soil fertility.

agriculture on straw-producing cropland would greatly enhance the potential resource efficiency of strawbale building, and promote the long-term viability of the technology.

most strawbale structures are not entirely composed of straw. Almost all strawbale buildings include conven- tional building components in their foundations, roofing, mechanical systems and interior and exterior finishes. The total environmental impact of a strawbale structure must therefore be judged based on the sum of its con stituents, and not on the use of straw alone.

Implementation of the practices of sustainable

Strawbale builders should recognize, however, that

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Building with Straw Bales

Straw Varieties Straw varieties used for building applications

include barley, rice, rye, oat, flax and wheat. Barley straw is somewhat unpleasant to handle because of the irritating barley beards. Straw that has high silica con- tent, such as rice, is considered to be best for building, although farmers may be less likely to bale this type of straw since its abrasiveness can cause accelerated equip- ment wear. Almost all bales will have some seed and grain content, but those with a high seed content are less desirable for building. Seeds do not contribute to insulation value, are more prone to early decomposition than straw, and can attract rodent pests to the bales. Hay generally has a far higher seed content than straw, which is part of the reason straw is most often used for bale construction. A very high seed content in stored straw is revealed by the presence of rodent burrows throughout a bale stack rather than in just those bales touching the ground, which frequently harbor rodents.

Bale Density

erably between different suppliers due to different baling equipment and techniques. Dense bales are desirable for building, since using quality, heavy bales will make construction easier and the finished structure more stable and durable, as well as easier to stucco. Dense bales are less likely to break during handling and they add lateral strength to both load-bearing and non-load- bearing walls, and compressive strength to load-bearing walls. Some builders have constructed bale presses used to compact loose bales or regain compression of partial length bales, but bales that are dense enough not to

Bale densities, weights and sizes may vary consid-

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require additional compaction simplify the construction process.

Establishing a minimum acceptable density, rated by the weight per cubic foot, would ensure more uni- form bales that would provide more predictable performance. According to the City of Tucson/Pima County, Appendix Chapter 72 on Straw-bale structures, "bales in load bearing structures shall have a minimum calculated dry density of 7.0 pounds per cubic foot". The density factor is critically important in load-bearing- wall construction due to the structural stability gained from reducing the amount of deflection a wall experi- ences when lateral forces (such as wind loads) or transverse forces (such as roof or snow loads) act on it. The denser any homogeneous material- in this case the bales of straw- the more structural stability it will provide.

Moisture Content Bales should be well dried to insure proper stability

through initial compaction during placement. If the bales are wet when they are placed into the wall, exces- sive settling as well as obvious problems of decay could occur. Only dry bales are recommended for use in construction, and the dry bales need to be stored in a protected place until used. Wetness in the interior of the bale is revealed by breaking open sample bales. Any bale showing signs of mildew or active fungal growth, or with moisture sensible to the touch, is considered too wet for building use. The standard weights listed in the next section are also good indicators of density and possible moisture content.

bale weight. Moisture content needs to be controlled in order to reach a specified bale density as determined by weight. The city of Tucson code requires moisture content to not exceed 20 percent of the total weight of

The moisture content of a straw bale affects the

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the bale. Moisture content can be determined by insert- ing a probe to the center of the bale, and measuring the moisture content on a moisture meter.

Sizes and Weights

the most common type of bale varying by region. Tradi- tional square bales may have two or three strings of polyethylene binder twine, or occasionally are bound with baling wire. Fairly standard two-wire bales measure approximately 18x1 4"x36", and weigh 50-65 pounds. A typical larger three-wire bale size averages 23"xl6"x40" or longer. and weighs 70 to 85 pounds. Bales lighter than these weights lack sufficient density for structural strength and are considered unsuitable for use as a construction element.

Some people have experimented with construction using larger bale sizes, such as those designed for ma- chine handling. This increases the insulative value of the wall, but standard bales produce a wall that is of ad- equate insulative value for most climates, and using larger bales significantly increases the total materials cost of the building, reduces interior floor space and compli- cates handling as the bales are too heavy to lift and place by hand.

Bales come in a variety of sizes and shapes, with

Planning With Bales

wall height and window height dimensions to multiples of bale dimensions. When the wall and window heights are designed around the vertical dimensions of the bale courses, fewer cuts into the bales will be required. It is vital that a designer take into account the thickness of bale walls when planning a strawbale structure, and recognize that the building's "footprint" will be consider- ably larger than the usable interior space. In addition, a designer should not rely upon theoretically perfect bales

Strawbale construction is simplified by designing

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in developing a design, but base plans on the actual dimensions of bales produced by the particular supplier selected for the project. Height and width are generally not variable within a supply, as these dimensions are determined by the design of the baler and the dimen- sion of its compaction chamber.

Length of bales can vary considerably if it is not predetermined and conscientiously monitored. This makes planning more difficult, but can make actual construction easier, since a variety of bale lengths are available to choose from in filling spaces and staggering courses. However, even with careful design planning, some less-than-full-size bales will probably be necessary to fill in at corners and window and door openings. For this reason the designer may wish to plan building lengths to standard increments of plywood or drywall size rather than the more variable bale length. The use of 2-foot centers and 4-fOOt modules reduces materials costs and waste for any building components which are produced in standard-size increments.

Custom Bales Custom size bales are often needed to fill in at

doors and windows, to create specialized niches or partial walls, or to abut the structural framework of a non-load bearing construction. Creating the necessary custom-length bales is usually not complex or difficult. Full-size bales are split and retied by driving a threaded "bale needle" through the bale next to the existing twine at the desired new bale length. After the needle is pulled through the bale, the twine is tied around the new smaller bale, the old twine cut, and the excess straw pulled off and retied with the old twine. m e twine on the new, smaller bale lies along the bale a p proximately where the old twine ran. A "truckers' hitch" is used to cinch down the intact bale before it has time to expand or fall apart.

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Special half-bales produced in the field by the baler may be less dense than full length bales, so it is worth producing the necessary custom bales on site, using the method described above. If necessary the custom bales can be recompressed to an appropriate density using a bale press. Rice straw bales have been reported to be very difficult to cut and to separate.

Sometimes it is not just a shorter bale that is needed, but an odd-shaped bale to fit around plumbing, roof trusses, or framing. If bales need to be notched or trimmed, an antique hay saw, a chainsaw or a crosscut hand saw is used. Care should be used in notching bales: if the twine is unintentionally severed, bale com- pression can be lost, and twine will jam a chainsaw. Straw that is very high in silicates can dull cutting edges rapidly, but is generally not considered otherwise prob- lematic.

Four to five inches of straw can be notched out of the side of a bale before the strings are encountered. An end-notched or beveled bale is created by shortening only one of the bale strings, and pulling off the excess straw by hand.

Orientation of Bales

top and bottom, are dimensionally more stable than bales stacked on edge (with strings running around the sides) and consequently bales are generally used flat in load-bearing applications. When used flat the bales also provide a thicker, more insulative wall. If bale strings break, the straw will be contained by pressure of sur- rounding bales. Bales can be used on edge, however. for specialized nonload-bearing applications and crest- ing partial-height bales or curved walls.

Bales stacked flat, with strings running over the

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Advantages of Strawbale Building

Aesthetics

tion attractive. The wide walls that characterize bale construction make possible window seats and various interior designs and accessories. Strawbale houses can be virtually indistinguishable from the common and popular double-adobe houses of the American South- west. The technology allows a variety of architectural expressions, and a number of ranch-style and even saltbox bale homes have been designed with the specific intent of blending in with their more conventional neighbors.

Many people find the look of straw bale construc-

Labor

advantages over conventional stick framing and over other types of indigenous building. First, it can be less labor intensive than adobe or stone construction. The wall-building process is simple and can proceed quickly, especially for load-bearing wall designs. Individuals with no previous building experience can be taught how to work with strawbales, which can reduce the labor time charged by a contractor and traditional framing laborers.

It must be noted that the use of norwxperienced builders is both a potential advantage and disadvantage of straw building. The potential cost-savings must be weighed against the potential for structural failure or reworking made necessary by improper design or appli- cation.

Strawbale building has a number of potential

Cos t-eff iciency Straw bale building can be a relatively inexpensive

way to create a superinsulated wall structure. Attention

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to maximizing the lowost potential throughout the rest of the building is a must, however, if the entire structure is to be cost efficient. It is true that, based simply on a price per square foot of highly insulated wall area alone, bales themselves are generally inexpensive building materials (although price varies by region and season.) The wall system is superinsulated and simultaneously relatively easy for unskilled labor to assemble.

The hopeful builder should remember, however, that the total materials cost of a structure rises rapidly as other elements besides walls are added: foundation, roofing, flooring, wiring, mechanical systems, cabinetry and finishes, as well as any paid skilled labor costs ac- crued. In addition, the cementitious stuccos commonly used to finish strawbale walls can add significantly to the cost of the walls and, ultimately, the cost of the total structure. Strawbale walls do lend themselves to finish stuccoing with adobe (in most climates), a material which is "dirt cheap" and maximizes the opportunity for owner labor, but which requires vigilant maintenance.

In fact, the cost of walls is usually only 20% of the total cost of a conventionally contracted and built stick- framed house, so substituting bale walls alone does little to reduce the overall cost of a building project. It would be very easy to lose the limited cost savings possible with strawbale walls if time is lost training contractors to tie in floor and roof systems to the unconventional wall sys- tem. The savings of an easy-to-build system are realized only if the owners can actively participate in the work or if they can hire inexpensive unskilled labor. The reputa- tion of strawbale construction as an inexpensive way of building persists because strawbale wall construction can lend itself as a complement to a spectrum of other lowtost design elements.

The reputation persists as well because of the nature of the average straw bale house and the way in which its accomplishments and shortcomings are pre-

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sented by the proud owners. Many houses that have been built have been very modest structures of simple design, with little or no extravagance in interior finish, plumbing and accessories. The materials cost is often presented as the full financial cost of the house, with labor costs often underestimated or understated. Barter and salvaging may leave no trail of receipts, but in fact represent an investment of time and resources often unrecognized in strawbale building cost estimates.

tings; many without engineering or architectural consultation. Urban versions of the same dwellings would necessarily encounter additional expenses for engineering and building code approval, especially during the pioneering stage of this technology’s develop ment.

and complexity and specific structural and finish materi- als chosen by the owner. No average price statement is possible, but the following is a general outline of price ranges, per square foot, for structures built with strawbales and employing various materials and prac- tices:

Very low: less than 1000 sq.ft. at $7-$20. Very simple design. Strawbales are not the only low cost materials. Uses salvaged and reused materials. Owner takes on all labor. Built on a rubble trench foundation. Adobe stucco finish. Many of the lowest cost houses do not have running water or electricity.

Low: 1000-1 400 sq.ft. at $20-$50. Simple design. Uses salvaged or inexpensive new materials. Owner- built walls and finishes. Subcontract foundation, plumbing and electrical. Interior walls of adobe stucco or drywall. Exterior finish of stabilized adobe stucco. Strawbales are load bearing.

Moderate: 1400-2400 sq.ft. at $50480. Owner may provide unskilled labor. Predominately contractor

Most bale structures have been built in rural set-

Housing cost is largely dependent on design size

built. Conventional heating and cooling systems. Aver- age priced finishes. Cementitious stucco wall finishes interior and exterior.

Custom design. Luxurious home. Contractor and craftsperson built. Cementitious stucco exterior wall finish. Plaster or cementitious interior wall finish. Cus- tom interior finishes.

In summation; at this time much of the sense of, and advantage of, strawbale construction is realized in rural settings and projects where other elements of design are tailored to equate with the low-cost bale wall. Much remains to be done before urban strawbale build- ings are able to fully utilize the potential cost advantages of building with strawbales.

High: 2400-4000 sq.ft. at $80-5 130 or more.

Insulation and Soundproofing Bale building combines highly insulative walls with

moderate thermal mass properties. A properly built bale wall compares in thermal efficiency to a superinsulated stick-framed wall. Although resistance to heat flow (R- value) depends on bale size, type and density, plaster-finished strawbale walls can achieve R-values as high as R-40-50. Builders should note, however. that for a structure to achieve full insulative value, thermally efficient walls should be combined with well insulated roofs, foundations, windows and doors.

Thick external bale walls also serve to reduce sound transmission. Stand-alone strawbale walls have been built as acoustical barriers and sound walls to screen busy streets from residential areas. Although Sound Transmission Class testing has not yet been done on bale walk, an STC rating for a plastered straw-bale partition with no openings has been estimated by the authors at around 50 dB.

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Disadvantages of Strawbale Construction

Unfamiliarity

that not many people are familiar with their structural properties. Would-be builders should use caution in planning and embarking upon strawbale building projects. Deviations from standard construction practice that are necessary for working with strawbales can cause complications, misunderstandings and delays with architects, builders and subcontractors, as well as insur- ance providers, code officials and bankers. Due to the increased interest in alternative building materials and methods, and educational activities sponsored by strawbale building advocates, many of these difficulties are gradually being overcome. Experienced strawbale builders can often help novices overcome technical and logistical problems.

The foremost disadvantage of using straw bales is

Lack of Testing A correlative disadvantage is that the use of a

relatively highly compressive material such as bales, especially in load-bearing walls, is not well understood from an engineering standpoint, mainly due to the lack of testing and prescriptive standards. The majority of existing buildings were not subject to code review and the engineering that went into them was often of the "intuitive" variety. It should be noted that the success and longevity of many buildings confirms that bales do indeed lend themselves to intuitive usage in small struc- tures. On the other hand, there is little record of the failures experienced by historical strawbale buildings.

At this time there are many people and organiza- tions working towards a prescriptive standard for

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strawbale building and formal codification of the tech- nology. Additional information and updates on this process can be obtained from organizations listed in the reference section of this booklet.

segment of owner-builders to the call for testing and codification of standards. This resistance seems to stem from an assumption that codes will nullify the best as- pects of strawbale construction, namely simplicity and low cost. As code jurisdiction continues to encompass rural areas, however, opportunities to build with strawbales will soon require resolution of questions of engineering and safety. Strawbale construction in most urban areas is already constrained by building codes put in place to ensure structural integrity, durability and safety.

There is a great deal of resistance among a large

Reduction In Floor Space

the usable interior floor space of a building as related to exterior dimensions. About one square foot of floor space is lost for every lineal foot of wall, as compared to a conventional 2x6 stud wall. As a result, plans for living spaces need to be based on interior, rather than exterior room dimensions. As a consequence of the thick wall, strawbale houses leave a larger "footprint" on the land per usable square foot of interior space than their con- ventional counterparts.

Due to their extreme thickness, bale walls reduce

Potential for Complications Simple bale walls can become complicated very

quickly as a builder adds windows, doors, mechanical systems and nailers for cabinetry. Solutions to detail problems require intuition and innovation and cannot simply rely on accepted conventional construction prac- tices. Strawbale construction demands a lot more than simply stacking 4-fOOt long building blocks, and the

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challenges posed by constructing a stable wall and tying the wall to the other elements of the structure should not be dismissed or underestimated. Turning t h i s poten- tially discouraging disadvantage of strawbale wall usage to an advantage requires that the house designer apply an equal amount of ingenuity to solving, simultaneously, the cost and complexity challenges of roof, floor, wiring, heating and cooling systems and finishing details.

Strawbale walls lend themselves best to simple rectangular structures. Creating a complex wall with many angles and levels is a difficult engineering and construction feat. Strawbale walls are best used in applications where their advantages are maximized, and should be used cautiously or avoided in applications where complex designs are needed or desired.

Extensive Use of Cement and Steel

construction is the unexpectedly high price and exhaus- tive labor of applying stucco to poorly built walls. Cement stucco is not cheap, and if the surface to be stuccoed is not as flat and smooth as possible, the amount of stucco necessary to fill in voids for a smooth surface can quintuple finish material and labor expense. An uneven building stuccoed smooth with cement may need such a thick coat that it becomes more of a "ce- ment'' building than a straw building. Using this much energy- and pollution-intensive cement stucco negates much of the environmental advantage that straw build- ing enjoys. Careful construction practices that keep walls plumb and smooth can help to prevent extensive cement use.

rod, clips, pins and wire are usually used. This steel is highly energy intensive to produce, and is non-indig- enous to most areas. Although some of the functions served by the steel can be fulfilled by wood or plastic,

A commonly occurring problem with strawbale

In order to tie bale walls together structurally, steel

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the amount of steel required for structurally sound wall construction should be recognized by anyone consider- ing building with bales. One may want to think about the amount of rebar necessary to tie bales together and consider alternatives such as bamboo or other wood products.

Difficulty in Financing

conventional financing for a strawbale house, there are obstacles. In many cases if the house can get a building permit it can also qualify for a loan. In Bellingham, WA First National Home Mortgage has initiated a program called Greenloan. It is a program to arrange construc- tion and conventional financing on strawbale and other alternative housing styles. This may be a good reference point for anyone trying to get financing for a strawbale house. The loan officer for the program is Jeff Albrecht. He can be reached at 800-738-6720.

Although there are examples of people receiving

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Bale Wall Construction

There are two basic types of strawbale construc- tion: load-bearing bale walls, in which the bales provide both total structural support and insulation, and infill bale wall combinations using metal, wood, or cement structural frames to support loads and straw bales as insulation.

Bales as lnfill within Structural Systems Bales can be used as infill in a structural system,

and this is the type of bale construction most likely to be approved by building code officials. The structural system most often combined with bales is a traditional pole or timber frame structure. In this type of structure the bales are either installed as an uninterrupted exterior curtain wall outside the structural framework, or are carved to fit between members of the frame.

used in combination with bale walls, and bales have even been used as a retrofit envelope application for existing buildings, including mobile homes. In any strawbale infill application, it is important that the struc- tural framework used conform to engineering standards for loading, shear strength and racking, and that the bales be adequately tied to the structural framework.

Metal frames or other framing systems may also be

Opening 5 When bales are used as infill in a structural system,

there are several options for framing window openings. The window frame can be supported by the foundation, or by adjacent vertical framing members. The window could also float in the wall, as it does in a load-bearing wall, but since the infill bales are not compressed by roof weight, the unsupported window may be more prone to displacement. In a strawbale infill wall, window and

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door openings are spanned by headers adequate to support the weight of the bales above them, even though roof weight is supported by the structural frame.

Finishinq

complicated than finishing a load-bearing wall. A non- load-bearing wall is easier to keep straight during construction because the bales do not get as compacted and possible consequent deflection is lessened. Also, taut wire mesh can be placed on the outside of the wall to define the wall plane. This holds the bales in line during placement and creates reinforcement and an attachment for the stucco.

Finishing a nomload-bearing wall is somewhat less

Use of the Bale as a Load-bearing Element

Load-bearing construction relies on staggered courses (a "running bond") of bales to provide structural strength for the wall and support the roof weight. Mall building is simplified by building the wall to an arbitrary multiple of bale height. Load-bearing ability should be sufficient in a typical onestory structure where the total roof load (live and dead loads) per linear foot is unlikely to exceed 550 pounds. Additionally, load bearing bale structures should be designed to withstand vertical and horizontal loads similar to the code specified for tradi- tionally framed structures.

&? of Top Plam A top plate for the wall is prepared to match the

overhead plan view dimensions of the foundation. The top plate is placed on top of the bale wall (paralleling the foundation) to stabilize the wall, keep it from racking excessively, bowing outward at the top, or losing its intended shape. The top plate does not eliminate the tendency of the wall to twist or corkscrew as it settles.

28

This problem is prevented by using cables or cross- bracing in wall construction.

combinations of lumber and OSB or plywood. They should consist of two pieces running on each edge of the course, with blocking pieces across the bale. Other types of top plate, such as metal or concrete, are also possible. When the wall reaches desired height, the top plate is installed using cable run from anchors in the foundation, up over the top plate and back down to the opposite side of the foundation.

A common rule of thumb is that a load bearing wall will take at least a month to settle from the weight of the bales themselves and the weight of the roof. Loose bales can take even longer to settle. Continued monitoring of the walls will reveal the rate of settling. Slack in the cable is taken up as the wall settles, and the ties from the top plate to the foundation are adjusted continuously to prepare for the possibility of high wind or seismic activity.

Some builders have devised systems that allow the wall to be precompressed using allthread rod or external tensioning systems. Such methods shorten settling time, and allow construction to proceed. In any load-bearing wall, no stucco should be applied while settling is mea- surable.

Top plates can be constructed of wood I-beams or

Cross-Bracing Cross-bracing of some type is generally used in the

wall to add the support of a tension member and im- prove lateral stability. This bracing is accomplished with traditional methods of diagonal bracing using steel bracing strips or building-specific cable systems. The braces are attached to the foundation at the corners of the structure and taken diagonally up to the top plate.

29

Reinforcina Rods Rebar, steel rod, wood stakes or bamboo are com-

monly used to cross tie each course of bales to the ones below as the wall rises. The pins are driven at an angle 10 to 20 degrees from the vertical, in the center of the wall. Driving the pins vertically may allow the pins to slide between the straw flakes that make up the bales and this may compromise the resistance to lateral dis- placement that these pins are meant to create. (These flakes are formed due to the reciprocating piston action of the baler.) An often-quoted rule of thumb is two pins per bale.

Recent testing has been done using twelve 5-fOOt pieces of rebar in a 12'x8' wall panel. This averages out to one rebar for every foot of wall, an extensive use of energy-intensive steel within the walls. This procedure does provide excellent support against lateral loads (see testing section of this paper). Long vertical pins at doors and corners also serve to stabilize the wall. Rebar bent in staple shapes is used to join bales that meet at wall corners.

lmporta nce of E nd Walls and Connections

lateral wind loading is provided by the end walls and inter-wall connections. Reinforcement is built into all corners both vertically and horizontally for the transfer- ence of lateral loads at these points.

The critical support that allows walls to withstand

Alia nment

and aligned by means of temporary corner braces and through careful attention to keeping them plumb. By beginning stacking at corners, full length and "factory edged bales can be used in the corners and fill-in is done at the wall interior or at window and doors where partial bales will need to be manufactured anyway. Small

As they go up, load-bearing walls are kept straight

gaps in the wall are stuffed with loose straw or with the "flakes" of straw from a broken bale. The need to shim courses to keep them level reveals improper stacking, uneven tamping of the bales by walking or working on them, or varying and low density of bales.

Openinas Rough openings and headers for windows and

doors are installed in advance of laying up the bales next to and above them. In a load-bearing wall, window frames often consist of self-contained boxes that are attached with pegs or pins to the surrounding bales, so that they "float" within the wall. If the bales settle exces- sively or unevenly, deforming or displacing the boxes, it can become difficult to install windows in these floating openings, so dense bales are an advantage. Headers are generally installed to span the top of window and door openings, supporting the bales above them and distributing part of the roof weight to the bales around the window. To distribute the load these headers are generally built to extend about 20" on each side beyond the opening onto the surrounding bales.

As with any type of construction, the wider the opening to be spanned, the stronger the header must be. Headers are usually dimensional lumber or engi- neered lumber beams. Depending on opening dimensions and the thickness of the header used, the next bale atop the header may need to be of partial height in order to level the course.

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Foundations for Straw Bale Structures

Straw bales generally rest directly on the founda- tion, with the exception of designs in which pole footings hold up a platform, or designs in which the bale walls rest atop the floor framing. If the bales rest on the foundation, it must be wide enough to support the bales used. The top of the footing should be situated at least 6 inches off the ground to protect the wall from ground moisture and runoff. Sealing the top of the foundation prevents moisture from wicking up into the bale wall. Foundations are sealed with a standard ce- ment sealant, or with roofing felt layered in asphalt emulsion. Roofing felt alone has been used in sites with welldrained soils and a dry climate. Twenty-four inch lengths of rebar placed vertically in the foundation serve to secure the first course of bales to the foundation. Straight rebar is set in the middle of the foundation with about a foot of its length exposed. This length extends upward into the bales above.

ing to below the frost line will use a huge amount of concrete and add considerably to the expense of the structure, a number of alternative foundation designs have been used with straw bale walls.

Because an eighteen inch wide foundation extend-

-pes of Foundations

load-bearing or non-load-bearing strawbale walls. Most of these examples are used to support either

Monolithic Slab Flooc While a monolithic slab floor may intensify the use

of concrete in the project, it eliminates the need for floor framing, and can be designed to contain a radiant heat

32

source. The monolithic slab prevents the need for pour- ing an 18” wide footer that extends below the frost line. Fly ash may be added to the concrete to reduce the total amount of cement used.

the slab for superior insulation and as a heat sink. Two concrete pours are required, one in which the bales are placed, and another in which they are covered with the pour. The result is an insulative, yet twice-as-concrete intensive, twice-as-expensive pour.

Some have suggested the placement of bales in

Rubble Foundations Another option is to develop an indigenous foun-

dation, rather than use the conventional concrete variety. Collected rock, rubble or salvaged masonry and concrete can be used as large aggregate for a cementitious foundation. The collected material is placed in the configuration of a poured concrete founda- tion and then stabilized with concrete, or the materials can be laid as masonry units using concrete as mortar.

A grade beam resting on a rubble trench is also used in very-low-cost structures. The trench is generally designed on a slight slope below grade to drain ground- water away from the walls. The trench needs to be as wide as the beam. Insulation should be run to the bottom of the trench, on the interior or. better, the exterior of the foundation wall.

Pole Footinas

ings. These require significantly less concrete than conventional perimeter foundations, which require a continuous grade or bond beam for the bales to rest on. In a pole footing concrete pillars are placed below the frost line at each corner of the structure, and the walls are built on a platform supported by the pillars. An anchor is placed in each pillar to tie the walls to the foundation.

Bale buildings have also been built on pole foot-

33

Cement Blocks Lightweight cement blocks and cementitious

blocks with recycled wood fiber or foam have been substituted for conventional concrete blocks to form foundations. These blocks are moderately more insulative than ordinary concrete masonry units, but block foundations can be expensive and time consuming to set up. If they are of interlocking design the blocks may be able to be dry-stacked, but otherwise require mortar.

In I Insulated shallow foundations, as recently intro-

duced to this country from Scandinavia, utilize a foundation that does not extend below the frost line. Rigid foam insulation board is attached to the outside of the footing around the foundation perimeter, to reflect the heat of the structure into the ground beneath it. This prevents the ground beneath the building from freezing. By circumventing the need to extend the foundation to below frost line, the insulated shallow foundation reduces the amount of concrete demanded by a footing for wide strawbale walls.

No Foundation Evidence suggests that simple bearing-wall struc-

tures have been built in dry climates with building paper or polyethylene-wrapped lower courses resting directly on 12 inch deep gravel trenches. Precise detailing and an extremely protected site would be obvious require ments of such an approach.

-34

Finishing Bale Walls

PreDarina the Wall for Finish

mesh that will eventually support a stucco or plaster finish, although some builders have applied stucco directly onto bales. The mesh used is usually either standard stuccoing mesh, or 1 " size chicken wire. Pieces of wire mesh can be attached to the ties within the wall, or wired completely through the bale to the reinforcing wife on the other side of the wall. The top and bottom ends of the wire attach to the top plate and to a wooden nailer on the footing. In applications where the bales are used as infill, the wire can be attached to the frame before the bales are put up. If it is stretched tightly enough, the mesh will then help to keep the bale wall straight and smooth as it is assembled. Pieces of wire that won't span a wall can be stitched or wired tightly together in order to provide constant tension across the wall surface. Once the bales are in place, the wire can be snugged securely to the stacked bales across the entire wall surface by sticking bent wire clips shaped like 10" long staples over the reinforcing wire and into the bales. The chicken wire or mesh on both sides of the wall is sometimes sewn onto the bales by using bale needles to stitch through the bale wall.

Before adding the stucco finish to the wall, it may be desirable to attach wood nailers at selected points in the interior wall, to allow for cabinet hanging. Nailers can either be sewn into a notch carved in the bales or (only once the settling is absolutely complete) can be installed to span vertically from the sill plate to the top plate.

Bale walls are usually covered with a reinforcing

35

Moisture Conce rns Trapping moisture within a bale wall can lead to

serious damage from moisture accumulation. Much of the moisture migrating into the walls comes from the interior, not the exterior of the house. Other moisture accumulation in the bales begins during the stucco process. While there is not a clear consensus on where moisture comes from and how to combat moisture, there are two points that are clear. First, as stated previ- ously, moisture content in bales prior to building should not exceed 20 percent; 10 to 15 percent is ideal. Second, when building, considerations should be made to keep moisture from condensing in the bale walls.

interior walls tight and the exterior walls “loose” or able to breathe. This does not necessarily imply the use of Tyvek or other vapor barrier on the interior, but rather the prevention of air leakage from the interior into the wall. Indoor moisture should be exhausted at its source, i.e. quality venting in kitchens and bathrooms. Some have even suggested locating bathrooms in the interior of the house, so that in the case of extensive water damage, bale replacement will not require the breaching of load bearing walls. The exterior wall should not be wrapped in a vapor barrier or other air or moisture trapping material.

In order to keep bales dry, it is best to keep the

Interior and Exterior Finisha

bales, are allowed to finish settling under the weight of the roof before plaster is applied to the surface. Al- though bale walls have been left unplastered for applications such as utility and farm buildings, in most houses the walls are finished with a stucco coat. This adds longevity to the wall through fire and water resis- tance, and helps prevent farm animals from damaging it or insects from infesting it. Wire reinforcement and

Load bearing walls, particularly those with softer

36

stucco finish also add strength and insulation value to the wall. Expanded metal lath at outside corners and openings is applied to help strengthen the stucco coat- ing.

There are a wide variety of stucco-type finishes, ranging from soft to hard. Adobe or gypsum plaster provide a soft finish that can be hand applied. Walls can also be hand-finished with cement plaster, color coat plaster, or stabilized adobe. Some finishes can be me- chanically applied with a sprayer. These include spray stucco, shotcrete and gunite; all of which are mixtures of cement, sand and water mixed at the nozzle of a m e chanical sprayer. In these methods, the force of the sprayer helps the surfacing material bond securely to the straw. Interior walls can be finished with various stuc- cos, conventional drywall or paneling.

A typical hand application process for cementitious stucco involves 3 separate coats: the scratch coat (a rough surface coat applied directly to bales or reinforcing wire), the brown coat (a smooth surfaced coat that fi l ls out low spots) and the color coat (a thin surface finish coat). The same stucco mix can be used for all three coats. Each coat is allowed to dry before the next coat is applied. The bales and the stucco should be misted with water, allowing the process of hydration to harden the stucco. Be warned however. that excessive "watering" of the bales may cause extreme bale deterioration if the bales are not able to dry.

Finishes containing cement can be expensive, particularly if there is variation in the wall that requires especially thick plaster in places in order to create a smooth surface. For this reason some builders use an adobe or asphalt stabilized mud plaster instead of a cementitious stucco. Adobe can often be made from locally available clay soil, but is vulnerable to moisture and requires more regular maintenance than stabilized finishes do when used on exterior walls. Maintenance

37

for adobe finishes is reduced by designing the roof to provide large protective overhangs and using weather- resistant materials such as cement in the splash zone near the ground.

for painting the finished structure. Using an integral color stucco eliminates a need

30

Roofing A hipped roof or "dutch hipped roof is a common

choice for load bearing wall construction, since it distrib- utes weight to all four walls. A hipped roof also allows all walls to be the same height and have level tops. Hipped roofs use less wood in their construction than some other roof types, but do not allow for easy addi- tions to the structure.

the gable construction the top plate is installed when the walls are at level, and the end gables are added above the top plate. To create a gable, bales are laid up in stair step fashion, and the steps are filled with loose straw. Shed or slant roofs are simple, but place greater weight on one wall than on others, which can lead to uneven settling of the walls. In larger buildings a shed roof configuration may be structurally unstable on load bearing walls.

Roof trusses can be used in combination with bale walls, and are attached to the top plate. A wider than normal truss, or a raised heel truss, will make installation of roof insulation easier. Roofs for strawbale structures should be designed with wide eaves, gutters and doww spouts in order to protect the walls from the weather as much as possible.

Gable or gambrel roofs are also used frequently. In

39

Code Considerations

One of the biggest barriers to widespread use of strawbale construction is the unfamiliarity of building code officials with the concept and performance of bale walls. The majority of bale structures built thus far have been in areas without building codes, but most cities and towns require code approval before construction.

Recently, the joint City of Tucson/Pima County, Arizona Building Code Advisory Committee approved an appendix chapter on straw bale construction for the Uniform Building Code. In the future this code language could be used to attempt to get strawbale construction written into code in other municipalities.

Code officials will more readily approve a strawbale infill in a familiar structural system than a complete load- bearing strawbale structure. Many code officials will be open to approving strawbale buildings for non-residen- tial uses, such as utility sheds. Working with a building code inspector throughout the design process will en- hance chances of project approval. Touring existing buildings and providing results of performance testing to familiarize officials with the technology will promote understanding and improve the likelihood of project approval.

While building codes are inherently conservative and can sometimes stifle development of alternative or new building technologies, they are enacted with safety in mind. Although strawbale walls have the potential to be very strong, stable and safe, it is also easy to under- engineer or poorly construct walls, which can lead to the construction of unsafe structures. Building codes help to prevent loss, damage and injury caused by unsafe constructions. Even in areas without code re- quirements, responsible construction is imperative and we strongly suggest professional review of structural details for any building project.

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Testing Data

Individual Bales Compression

Individual bale testing was done on three-string bales by a collaboration of people in the Tucson area. This testing, along with other strawbale tests mentioned in this paper, comprised the subject of a master's thesis by Ghailene Bou-Ali. The first set of three-string bale tests were performed on four bales laying flat, with the largest surface area horizontal in orientation. The bales were loaded up to 70,050 Ib. before the first failure was achieved, equivalent to 10,000 Ib. per square ft. The average stress capacity was measured at 75.80 psi and the average strain at 0.495 in./in.

The second set of compressive tests were per- formed on bales laying on edge. In this orientation the bales showed considerably less strength and stability than the bales laying flat. The horizontal bale's average stress capacity was 19.075 psi and average strain at .195 in ./in before failure.

Note: Both bale types rebounded to full height when compression was released, demonstrating elastic rather than plastic deformation.

Wall Panels

Lateral Deflection A testing program on out-of-plane lateral deflection

of straw bale wall panels was undertaken by the Com- munity Information Resource Center. They found that wall panels using 30 inch #4 rebar pins deformed under a light load and deflected severely long before the test reached the goal of the 23 Ibs/sq.ft., equivalent to 100 mph winds. They later replaced the 30 inch rebar with 60 inch rebar, running the rebar through four courses of

41

bales, two per bale. Thus, pins run from the first to fourth course, then the second through fifth course, and so on. With this amount of rebar. the maximum deflec- tion was 1 inch on each wall at the simulated 23 Ibs/ sq.ft. (1 00 mph winds). This extensive use of rebar tested very successfully, although one must consider the environmental and economic costs of using this much rebar. Bamboo or wooden stakes may be used in place of rebar, although driving them through the bales may be difficult.

The Construction Association/SHB AGRA Inc. has also done deflection testing. Using three 4'x8' unfinished wall panels, engineers tested for deflection when the panels were loaded at 20 psf, which is equivalent to 90 mph winds. All three test panels sustained the 20 psf load with an average maximum deflection measured at 1.206 inches. A stuccoed bale wall of the same dimensions was subjected to a 50 psf load and reached a maximum deflection of .22 inches. It should be noted that the parameters of this test were not very specific, as the weight, density, and configuration of the bales were not recorded. Documentation of the reinforcing and anchoring methods was vague as well.

The Mastets Thesis by Ghailene Bou-Ali provides further information on testing of wall panels. The di- mensions of the wall and the amount and placement of the rebar used were the same as those done on the second phase of the Community Information Resource Center test. Out-of-plane and in-plane lateral testing was performed on six 8x1 2' reinforced wall panels to mea- sure the deflection caused by simulated wind loads. The out-of-plane (loads perpendicular to the test panel) testing yielded a maximum deflection of 1 .OO inch occur- ring at the midpoint of the panel when loaded at 23 psf, which is equivalent approximately 100 mph winds. The in-plane (loads parallel to the test panel) lateral testing

42

yielded a maximum deflection of 6.00 inches occurring at the top of the test panel.

Fire testing sponsored by the Strawbale Construc- tion Association was performed by an engineering firm in order to establish codification of strawbale construc- tion in the state of New Mexico. In this testing a small scale E-1 19 fire test in accordance with ASTM standards was performed on both uncoated and stucco-coated strawbale wall panels.

Representing the configuration of a typical strawbale wall section, the test panel was composed of three courses of strawbales placed into a CMU wall and sealed with Kaolinite wool. This panel was then inserted into a sealed chamber and exposed to 1 000' F at five minutes, increasing to 1550" F at thirty minutes and 1750" F at one hour.

that the sample not exceed 250" F above the initial temperature at the exterior face of the wall. The non- reinforced bale reached an average temperature on the unexposed face of +52.8" F at thirty minutes, therefore passing the initial test with acceptable results. The burn- ing characteristics showed the straw to burn slowly with no deformation in the shape of the bales. Charring on the surface of the bales acted as a barrier and protected the interior of the bales from the heat, thereby delaying combustion. When the bales were removed from the CMU wall they burned slowly and did not burst into flames.

The stuccoed bale wall reacted by cracking when exposed to the fire testing, with little evidence of further distress. The stuccoed strawbale resisted flame penetra- tion for over two hours.

The National Research Council of Canada tested fire safety of plastered straw bale walls and found that they passed the small scale fire test with a maximum temperature rise of 1 10°F over four hours. Dense bales

The criteria for passing the ASTM E-1 1 9 test require

43

do not readily support combustion, and a solid bale wall precludes the chimney effect found in stick framed walls. Stucco further enhances the fire resistance of bale walls.

Compression

the strength of mortared bale walls. They found that a 12 x 8 ft wall did not fail when loaded with 18,000 Ib. of compressive load and 71 9 Ib. of transverse force. This translates to 45 Ib/ft2 live load, 60 Ib/ ft2 snow load, 16 Ib/ft2 wind load, and 48 Ib/ft dead load.

Canada Mortgage and Housing Corporation tested

In order for straw bale construction to gain validity in the general marketplace, it will be necessary to settle some of the remaining uncertainties about the perfor- mance of bales as a building element. A great deal of research and testing is currently underway, including efforts to find answers to some of the following pressing questions:

How do load-bearing walls perform over the long- term, when loading varies with snow and other live loads?

seismic activity? How do load-bearing walls actually perform under

. How can bales be rated for flamespread? . What is the potential for problematic pest infesta- tion conditions? . How do bales perform in varying conditions of moisture and vapor barrier placement? . Are there conditions under which wet stucco should not be applied?

What is the absorption capability and performance character of walls with no vapor barrier? . Can straw be used in lesstompacted form for fill or bagged insulation, and how does it perform?

44

A continuing challenge is to create guidelines for strawbale construction that ensure that it is simulta- neously safe yet lowtost, both in financial and environmental terms. Preserving these qualities is of prime concern if strawbale building is to be a viable alternative for individuals seeking to build affordable, resource efficient housing.

.

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Strawbale Building Resources People all across the North America are building

with bales. One of the best ways to learn more about strawbale building, and techniques that work and don't work in particular climates, is to talk with people who build and live in strawbale structures. The quarterly publication The Last St raw, produced by Out on Bale, offers a wealth of information on human resources and current events in strawbale building. The periodical serves as a connector between the many individuals and groups involved in building with straw.

Some architects and building firms specialize in strawbale construction. There are also a number of how-to manuals and other publications on strawbale building. Many organizations sponsor and conduct public workshops on strawbale building. There is even a strawbale forum on the Internet. This by-nmeans exhaustive listing of resources is meant to help those interested in strawbale building obtain further informa- tion and locate organizations in their area that are active in testing, educating or building.

by CRBT. Inclusion in this list is not a sign of endorsement

Black Range Films Star l?t. 2, Box 1 1 9 Kingston, N.M. 88042

A group offering video packages on strawbale construction.

by Matts Myhrman and Steve MacDonald A book on strawbale building that expands on previous texts by Myhrman and MacDonald. This publication is available from bookstores and organizations in this resource list that retail strawbale information.

The Canels ProjecVAthena and Bill Steen HC 1. Box 324 Elgin, AZ 8561 1

46

Conducts workshops on strawbale building, and offers publications and consultation.

Center for Maximum Potential Building Systems/Pliny Fisk 111 8604 EM. 969 Austin, TX 78724 5 12-928-4786

Developer of the ladder bale truss system, and expert in earth building and related resources.

Center for Resourceful Building Technology PO. Box 100 Missoula, MT 59806 (406) 549-7678

Information on resource efficient building technologies and materials.

DeHavillan Workshops 1039 E. Linden St. Tucson, AZ 857 19

Offers workshops across the nation on bale construction.

Design and Building Consultants, Inc./Paul Weiner 19 E. Fifteenth St. Tucson, AZ 85701

Design and consultation services on strawbale and other indigenous material buildings.

Development Center for Appropriate Technology/David Eisenberg PO. Box 4 1 144 Tucson, AZ 857 17 520-624-6628

Strawbale building research, consulting, and testing. Publications on strawbale building code compliance.

Ed Dunn/Solar Design and Construction 21 West Pine Flagstaff, AZ 8600 1 520-7 74-6308

Builder focusing on strawbale and other resource and energy efficient building practices.

EOS Institute 580 Broadway, Suite 200 Laguna Beach, CA 92651

Publishers of Earthword; Issue 5 devoted to indigenous architecture.

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GreenFire Institute 1509 Oueen Anne Ave. N., #606 Seattle, WA 98 109 tel/fax: 206-284-7470

Offering workshops, courses and retail publications on strawbale building throughout the Pacific Northwest.

The Last Straw Out on Bale (un) Ltd. 1037 East Linden St. Tucson, AZ a57 19

A quarterly newsletter containing updates on strawbale building testing results and regional resources, as well as articles contributed by various builders. Videos and books available. Out on Bale functions as the hub of the strawbale building network.

Tom Luecke 3785 Moorhead Ave. Boulder, CO 80303

Strawbale construction.

New Mexico Straw Bale Construction AssociationITony Perry 3 1 Old Arroyo Channso Santa Fe, NM 87505

Testing and code compliance work.

Jorg Ostrowski 1909 10th Ave. SW Calgary, Alberta T3C OK3

Research, workshops and consulting on strawbale building.

d S-David Bainbridge Biology Department San Diego State University San Diego, CA 92182

Basic publication on bale building, in bulk quantities.

Tom Ponessa 4 12 Palmerston Blvd. Toronto, Ontario tellfax: 4 16-537-1 969 mil: tomp@tvo.org

Architecvbuilder who researches sustainable building methods. Offers workshops/lectures on bale construction.

Resourceful Nest Jim Petersen PO. Box 641 Livingston, MT 59047

Builds strawbale homes.

Solar Energy InternationaVJohnny Weiss PO. Box 71 5 Carbondale, CO 8 1623

Offers intensive instruction on building with indigenous materials including strawbales.

SRW Construction/Stan Welch 1075 Montgomery Rd. Sebastopol. CA 95472

Strawbale construction offered, including seminars on strawbale technology.

Straw Bale Construction AssociationIBeverly Spears, Secretary 1334 Pacheco St. Santa Fe, NM 87501

National association of strawbale builders and designers. Offers technical information on testing and code status.

The Straw Bale House by Steen, et a1 published by Chelsea Green Publishing Company PO. Box 428 White River Junction, VT 0500 1

1994 comprehensive publication on strawbale building, with many illustrations, documentation of existing projects, and description of the elements of strawbale buildings.

Jhe Strawbale Primer/Steve MacDonald PO. Box 58 Gila, NM 88038

Basic publication on strawbale building, available in bulk.

Straw Bale Research Advisory NetwoMBob Theis Daniel Smith and Associates Architecture 1 107 Wrginia St. Berkeley, CA 94702 (51 0) 526-1 935

Fosters coordinated strawbale testing by coordinating regional efforts.

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Sustainable Systems Support/Carol Escott 6 Steve Kemble PO. Box 318 Bisbee, AZ 85603

Offers videos, including The Elegant Solution", and infor mation packet.

Scott Weston 2 1 1 Lakeside Ave. Coeur d'Aene, ID 838 14 tel/fax: 208-773-5776 e-mail: Row WestoC9AOL.com

A building contractor focusing on strawbale design and construction.

lnternetSources The Strawbale Construction Web Information Page

http://solstice.crest.,org/efficiency/straw-insulationh ndex-html

The Hay Bale Construction Party http://solstice.crest.org/efficiency/straw-insulation/eip/ hay. html

View all strawbale posts at the archive of posts http://solstice.crest.org/efficiency/sy/strawbale-list-aKhive/ 0878.html

A list of people associated with strawbale construction can be found at the following:

h t tp : / / so l s t i ce /c res t /o rg /e f f i c i ency /s t r list-members.html

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6

Technology - Fbstering. Efficimt Re"? Use. The Center for Resourcefuf Building Technology

(CRBT), founded in 1990, is a non-profit . ' organization whoke purpose.is t o educate the

public on a variety of issues relating t o housing and the environment, with particular emphasis

on innovative building materials and $ethnologies which place !e55 s t ress on

7

f regional anti global ecosystems.

,