by Kaki Hunter and Doni Kiffmeyer – Utah, USA

We live in the heart of the great Southwestern United States, surrounded by examples of one-thousand-year-old ruins left behind by the ancient civilizations of the Anasazi, Hohokam, Pueblo and many others. It was these original natural builders that inspired us to consider building with earth as a way to create beautiful, low-impact, energy-efficient housing that has endured the test of time to this day.

We started by teaching ourselves how to make adobe bricks, the most common earthbuilding technique native to the U.S. Making adobe bricks turned out to be a lengthy process that involved mixing the mud, pouring it into forms, lifting the forms, and then turning the blocks over the next several days to facilitate even curing. The blocks then had to be stacked and protected until ready for use. Manufacturing the adobes required a considerable amount of space for both the pouring process, as well as for storage of the dirt needed to make them, and then the storage of the adobe bricks themselves until they were ready for building. We live right in the heart of a small town, which made this process a little tight.

The dirt for adobe block and most other forms of earthen architecture require a specific ratio of clay to sand, ideally about 25 to 30 percent clay to 75 to 70 percent well-graded sand. In some cases, a stabilizing agent may be added to an earthen soil to increase its compressive strength and make it resistant to the affects of water. Some earth building techniques like cob require copious amounts of straw fiber added to the mix. In most cases, adobe brick also benefits from the addition of straw or some other kind of natural fiber.

Honey House

After our initial foray into homemade adobes, we read about the work of international award-winning architect Nader Khalili. Nader is an Iranian-born architect who abandoned a successful career designing skyscrapers to follow his heart, which led him to create an innovative sandbag/superadobe/earthbag architecture as a means of providing low-tech, enduring affordable housing. Inspired by the ingenious monolithic adobe buildings of his homeland of Iran, Nader conceived the idea of building domed and vaulted structures with…bags of earth. We took a one-day workshop with Nader and we were hooked! We returned home excited to build our first earthbag-wall project, a privacy wall opposite the busy baseball field across from our house. However, our interest quickly zeroed in on the building process itself. We began innovating tools, tricks, and techniques that we felt made the building process more enjoyable and the results cleaner and predictably solid. We coined the acronym FQSS which stands for Fun, Quick, Simple and Solid. The process has to be Fun, which makes the work go Quickly as long as the procedure is kept Simple and the end results are Solid. Hence the FQSS stamp of approval became our dirtbag golden guideline.

Earthbags (as we were soon to discover) had the advantage of being able to use a wider range of soil types than traditional earth building techniques – “Wow, this dirt’s just got five percent clay and it still works!” We have been able to adapt soils for use in earthbags that have ranged from zero clay to 50 percent clay content. No type of fiber was needed within the soil. Since the bag acts as a textile container for the earth, the woven fibers do the job of stabilizing the soil in place so the soil can have a lesser quality binding strength than required for most other types of earthen construction. When necessary, even dry sand can be used as fill, as could be the case in providing emergency relief shelter. The Earthbag System is a contemporary form of earthen construction that uses modern woven polypropylene feedbags (usually misprints) or long tubes as a flexible textile container (or what we call a flexible form) preferably filled with dampened soil. The bags or tubes are filled in place on the wall being built so there is no heavy lifting. After a whole row is laid, the bags are compacted from above with hand tampers. The compacted earth later cures to a cement-like hardness. Two strands of four-point barbed wire are laid in between every row that act as a “Velcro” hook-and-latch mortar, cinching the bags together while providing continuous built-in tensile strength. Tensile strength inhibits the walls from being pulled apart during stressful conditions like earthquakes, floods, hurricanes, and load-bearing and lateral forces. The combined strength of the four-point barbed wire sandwiched in between the woven textile fabric of every row of earthbags adds a significant degree of tensile resilience that is lacking in most traditional forms of earthen architecture.

The soil we selected for our initial earthbag building projects was delivered from our local gravel yard at 80 cents per ton. That was ten years ago. Today we pay about $1.80 per ton. Reject sand or crusher fines are common names for the clay fines that are the byproduct from the manufacture of washed sand and gravel produced at most developed gravel yards. Often, this reject material has sufficient clay-to-sand ratio to produce strong compacted earthen blocks. However, over the years, we have had considerable success with using almost any type of soil available on site by paying particular attention to adjusting the moisture-to-soil ratio that produces the optimal strength block.

Building the earthbags around temporary rigid box and arch forms creates door and window openings. After compaction of the keystone bags, the forms are then removed. Wood-strip anchors are installed during the wall-building process, providing an attachment for bolting on doorjambs, cabinetry or wood-frame intersecting walls, electrical outlets and plumbing systems.

Wall plastering options range from thick natural earthen plaster applied directly over the surface of the bags (yes, it sticks!) or, for additional protection, lime plaster can be applied over an earthen plaster. Cement/lime based plasters perform well when the earthbags are filled with a stable, well-draining sandy soil and applied over stucco mesh (chicken wire). Plasters can be applied by hand or sprayed on with a pressurized plaster sprayer for a unique contoured effect that accents the shape of the bags or tubes.

Earthbag Architecture can be designed to suit a wide variety of climates. Since the woven polypropylene bags are virtually rot proof, earthbags are an excellent choice for underground structures: root cellars, storm shelters, bermed homes and greenhouses. In climates where wood is scarce, whole houses can be built exclusively with earthbags including the foundation and roof, as is the case for corbelled earthbag domes. Earthbags also combine well with other natural building materials that can be combined together to create hybrid structures. Straw bales can be interlocked with earthbags to build sturdy arch entryways or to add thermal mass to the interior wall of an attached sunroom. Or we may choose to use earthbags for the sunken first level of a structure and then switch to strawbale, post-andbeam, cob or adobe brick for the rest of the wall above grade to make use of an available resource or add aesthetic variety.

The advantage of combining two alternative natural building mediums: load-bearing earthbag walls provide mega-thermal mass, while an exterior straw-bale wrap provides mega-insulation.

Insulation strategies for earthbag walls offer a variety of options. Narrow tubes provide a sturdy load-bearing wall with plenty of thermal mass, while straw bales secured to the exterior of the wall provide ample insulation. Now, we have mega mass coupled with mega insulation to provide the best use of both of these materials in one building. Another way to add interior mass is to build our interior walls with earthbags and our exterior walls with straw bales alone. Another approach we have experimented with is mixing a percentage of 3/4-inch pumice to a quality rammed earth soil that captures air spaces within the earthbag itself. A 50/50 mix of suitable earth and pumice make the bags one third lighter than their normal all dirt weight yet still makes a nice hard compacted earthbag.

Building codes

The advantage of combining two alternative natural building mediums: load-bearing earthbag walls provide mega-thermal mass, while an exterior straw-bale wrap
provides mega-insulation.

The earthbag building system has been extensively tested by Nader Khalili in conjunction with the ICBO (International Conference of Building Inspectors) and the Hesperia Building Department in Hesperia, California, at the California Institute of Earth Art and Architecture for earthquake resilience, loadbearing, and shear strength stability, all of which were proven to far exceed conventional code standard acceptance. (See Building Standards issue Sandbag/Superadobe/ Superblock Sept-Oct 1998 for a full article on the merits of Earthbag structural nitty-gritty).

Resources

Sources for bags and tubes can be found on the Internet under woven polypropylene feed bags. Our favorite U.S. supplier for both pillow-pack and gusseted misprint bags is www.innpack.com, toll-free 800.622.3695 in Tennessee. Typical prices for 50-lb misprints are approximately $.17 each (USD), and 100-lb bags are $.25 each (USD). Both come in bales of 1,000 bags. Smaller quantities for bags and tubes are available from a Kansas City, Missouri, source www.centralbagcompany.com 816.471.0388. Ask for Chris Klimek for prices and selection. Also try 800.521.1414 www.fultonpacific.com.

For step-by-step nitpicking details about building with earthbags, check out our book Earthbag Building, the Tools Tricks and Techniques by Kaki Hunter and Donald Kiffmeyer, New Society Publishers, 2004. Or call us at 435.259.8378, or visit our web site www.okokok.org.

Donald Kiffmeyer and Kaki Hunter have been involved in alternative construction since 1993, specializing in affordable, low impact and natural building methods. Inspired by the work of visionary architect Nader Khalili, the grandfather of Sandbag/ Superadobe/Earthbag architecture, they wrote a screenplay entitled “Honey’s House,” a film about truth, justice and affordable housing. From these innocent beginnings, they were launched into the alternative building movement where they were encouraged to share their combined innovations to establish the Flexible Form Rammed Earth technique. Together they co-authored the book Earthbag Building, the Tools, Tricks and Techniques by New Society Publishers. They live in Moab, Utah, where they continue to focus on the research and development of fun, quick, simple and solid natural and alternative building techniques that are inspired by this fabulous planet.

Slope pan flashing to outside.

Included in TLS #49 (Myths and Realities, Spring 2005) was a discussion of ways to deal with moisture at the bottom of windows. David Eisenberg shared a written design detail for a pan under the window to carry water away from rather than down the wall. We wanted to share a drawing of this detail and David kindly provided one for us to share in Tech Tips.

Here’s the portion of the discussion in which David details this design idea.

“Protecting the bales beneath the windows requires that you catch the water under the window and make sure it gets all the way out of the wall. In other words, ideally, you would have a pan of sorts under the window, sloped slightly to the outside, extending a bit beyond each side and with a lip at the back and on each end (so water can’t just run off the ends), and extending out beyond the exterior wall surface, with a drip edge – so that any water that leaks through or runs down the sides of the window ends up in this pan and is shown the exit. You can make these pans out of metal, plastic, ice and water shield, cast this shape into a concrete sill, anything that will keep the water from leaking through it, but the principal thing here is to make sure that the water can’t get into the wall below the window. You can put your window sill material, whatever it is, on top of this pan flashing being careful not to punch unsealed holes when you install the sill. It can take a little thought and ingenuity to do this, but it assures you that, when the windows leak, the water leaves the building.

Concept of pan flashing turned up at back and sides extending beyond exterior finished wall with drip edge. Extending behind finish or trim at each side of opening.

“That old practice of just putting roofing paper or plastic over the top of the bales and setting your windows on it and then plastering over it just leads the water down inside the plaster to the bales wherever the water protection ends unless it runs continuously down the wall under the window to below the bales (and we don’t recommend doing that).  It just temporarily moved the problem down, didn’t solve it.”

What is the ratio of your mix? Let your sand tell you!

This article is original content and has not appeared in The Last Straw.

St. Astier Natural Limes, a producer of hydraulic lime products from France, is offering a set of DVD videos called The Master Stroke DVD Tutorial Series.  The Master Stroke is a 4-disc series beginning with lime mortars.  Other discs cover plastering and rendering with lime, and building and pointing with lime.  In this article we will review the first in the series, Making Lime Mortars.

The content of the DVD is laid out very clearly and is easy to follow.  The quality of the video is very polished. The main purpose of the DVD is to show the construction worker how to create a consistent, high-quality mortar or render.  Tips include how to properly keep your sand dry, how to measure each bucket of sand, etc.  But there was one piece of information that really make this video important.  Nearly half of the video is dedicated to the concept of the sand void ratio and how it affects your mix.

Have you ever wondered where the ratios we use for our mixes come from?  This video explains how they are derived.  Without going into too much detail, the ratio of sand to lime is determined by finding the void ratio of your sand.  Once you know how much air is between the grains of sand you can find the volume of binder.  If you use too much binder, the sand particles will be far apart, separated by water and lime.  If you use too little lime you are not filling all the voids with lime and you will have pockets of air and water.  The perfect ratio is one that fills all the voids and leaves little room for air or water.  Once you know this ratio, based on your sand, you can then adjust the ratio to achieve your desired results.  Don’t think you can just figure this out on your own through this article.  There is a proper way to do this, and each step is clearly defined in the video.

To know the proper ratio of sand to lime (or any other binder – clay, cement, gypsum, etc) is like an enlightenment for most of us.  Have you ever wondered why the code says 4:1:3/4 (sand:cement:lime), or why your friends used 1:2:9 (cement:lime:sand)?  Now you don’t have to guess.  Watch this video and learn how to properly measure the void ratio of your sand and the ratio of sand to binder.  It will become apparent that the mix your friends are using on their project has little bearing on your mix.

Mortars, renders and plasters all folow the same ratio and mixing concepts.

Learning how to derive the ratio of sand to binder is obviously very valuable.  The rest of the video walks you through the measuring and mixing process, showing how a professional would prepare his or her mortar.  After being a sub-contractor and mixing thousands of batches of plaster, this video would have been great as a tool for estimating.  In my mind it creates a baseline for high-quality that a builder can use to determine costs.

In summary, I would say buy this video!  It can be purchased at the link above for $39.  From novice to professional, you will find value.  Good luck.

This review is intended to be objective.  No compensation of any form has been accepted in connection with this article.

by Wayne Bingham and Colleen Smith – Idaho, USA

Our interest in straw-bale construction grew out of our concern for energy efficiency. Our research into building energy efficiency grew into an awareness of sustainable building practices. An urge to build an energy-efficient home of materials that are sustainable grew as we explored these issues.

As we examined the site conditions for our home in Idaho, we found prevalent winds came from the southwest, passive solar orientation was due south, and views were predominantly southeast toward the Teton mountain range. The homestead to the west anchored the place visually and the rolling grass and grain fields to the north and east held their own hypnotic beauty.

We asked ourselves, “How do we place a building here and what would it look and feel like?”

From Small Strawbale by Bill Steen, Athena Swentzell Steen and Wayne J. Bingham. Published by Gibbs Smith

We walked the site many times over several years, searching for the right place to build and the right kind of structure to build to respond to the soil, views, and
weather. When the irrefutable drive to build overwhelmed us, we went to the land and stayed for three days, walking, feeling, talking, and looking for the right place. We examined alternative ways of achieving solar gain while maintaining prominent views and avoiding challenging weather patterns.

The summer sun in our high mountain desert can be intense. The days can be hot, evenings cool down fast when the sun goes down, and the nights are cold. So a porch wrapped around straw-bale walls made sense to us. It can protect us from the sun, provide outdoor living space, and allow the straw bales and the internal thermal mass to moderate and maintain a relatively even temperature inside the house. The porch would also serve to protect the earthen-plastered bales from the weather.

We wanted the house to sit lightly on the land and allow the rolling surface of the earth to flow unimpeded past the house. We raised the porch surface only six inches
above the adjacent ground around the entire perimeter to require only one step to grade.

We have visited and experienced several houses that deeply impressed us and we developed several drawings to reflect this approach. They were approximately square, had hip roofs and wrap-around porches. The deep porches were occupied with plants, chairs, tables, firewood, clotheslines, and other apparatus for living out-of-doors under cover.

After consideration of many schemes, we settled on one that is 34-ft. square, providing 1,156 gross sf and 961 net usable sf. Seventeen percent of the total area is in straw bales and the house is 83 percent efficient. It has a kitchen/living area, one bath, a master bedroom and guest room. There is a loft for the grandchildren.

Photos by Wayne J. Bingham

Colleen had researched the area for organic straw bales that were 14-in. high x 18-in. wide. We found a farmer in Blackfoot, about 90 miles away, who had grown straw without herbicides or pesticides. Because the crop had matured and there was rain forecast, he cut and baled the straw. We had been working to have the house dried-in before taking delivery of the bales. We were able to place the bales under the newly finished roof before rains. Bale installation took only one week, notching and fitting under the roof and between columns and windows and doors.

Several friends called out of the blue and said that they heard that plastering was about to happen and could they come to help. Yes! Stan, John, Joe, Susan and I spent the weekend hand applying the beautiful chocolate colored earthen plaster mixed with long fibers of straw. We were at the end of summer and we wanted the plaster to dry before it could freeze, rendering earthen plasters no good. We were able to apply a rough coat on three walls over a three-day weekend. Brian and I finished the final wall in two days. The first weather coat had taken about one week. The building season ended and we left for the winter, planning to return the next spring.

When we returned in June 2003, we turned our attention to the final plastering on the main house. Sift clay, chop straw, mix clay to water, add straw and sand and apply to the rough coat completed last year. Check proportions, read the newly published book Natural Plasters, do tests and define how we want to do the work. Out of the research and study and questioning came a process we are very pleased with. We applied an infill coat of stiff plaster to the existing hand-applied rough coat using wood floats. We then brought the surface to within 1/4-in. of the /finish surface using a plaster that has more sand and less straw, sent through the chopper a second
time.

The final coat was applied with a steel trowel with curved corners, and polished with stainless steel Japanese trowels. It turned out quite nicely, with soft rounded corners and the bottom edge flared out to meet the metal drip edge.

We had read of clay “alis” paint. We read recipes in the two books and called the Steens asking for their advice. “Start with one part wheat paste glue, add two parts water, add clay until it covers your finger without showing a print.” We added one small scoop of burnt umber and about four cups of medium-sized mica flakes. We painted it on with 4-in. brushes, allowed it to become almost dry, and then polished with a damp (not wet) sponge.

Wow! What a difference it made. When plastering, the joints between one day’s work and another were visible, even though we tried diligently to feather it out. The alis unified the whole surface, and no joints were visible. It has a soft sheen from the mica, and it invites touch, as everyone who comes to the house exemplifies. Some have said it looks like leather. We think it looks like the earth around the house, but is refined by plastering and polishing. It looks like it belongs to its surroundings.

Building our house started out as a dream, a desire to do something sustainable, to build with one’s hands. Our project then became something physical, real, as we worked with the foundations, concrete, rebar, straw bales, earthen plaster, roofs, wiring, and all the rest.

In the summer of 2004, we installed a photovoltaic system to serve electrical needs of the house. We mounted the solar collectors on the garage porch. Batteries and inverter are in the garage with underground feeds to the house.

Well drilling estimates came in at $20,000, so we looked for another alternative. We built an 18,000-gallon underground cistern for a fraction of the cost that takes rainwater from the house and garage that passes through a filter before going to the tank. Before use in the house, it also goes through a charcoal and UV filter. It filled completely the first winter. With the exception of propane for heating and cooking, we are entirely off-the-grid. What a feeling of freedom!

Our home developed meaning for us beyond our wildest expectations. There has been a profound change in direction of our lives and satisfaction since we explored ways of becoming involved in sustainable building and focused on strawbale as a preferred method. Thirty-five years of life energy are focused on building our home. Feeling through our needs, responding to the site, and building the house day-by-day have been the most satisfying and meaningful experiences of our lives.

———————————————————————–

Wayne J. Bingham and Colleen F. Smith, a husband and wife team, have been involved since 1998 in straw-bale design and building. Their interest is an outgrowth of an exploration of energy efficiency and sustainable building techniques. In the mid-1990s, they attended several American Institute of Architect Green Building conferences where they began to understand the need for finding new ways to build without endangering the earth and its resources or future generations.  Seeking a direction of their own, they went on a natural building odyssey to the Southwest U.S. evaluating cob, adobe, rammed earth, earthship and straw-bale buildings, visiting or staying in each. They evaluated thermal performance, beauty, the feel, construction techniques and concluded that straw-bale building held the greatest possibility to satisfy their interest.

They attended The Canelo Project straw-bale and earthen plaster workshops and came away with a love affair with strawbale and earthen plaster that has not abated. Wayne immediately plastered their concrete block garden wall in their backyard with earthen plaster (see p 11 of this issue). They returned to the Steens in 1999 to spend a year involved with workshops, construction and collaboration with Bill and Athena on the development and production of Small Strawbale published in 2005 by Gibbs Smith Publishers.

Avid photographers and travelers, Wayne and Colleen have searched out and documented indigenous buildings in the United States, Greece, Great Britain and Italy and have developed a large library of images that were the start of the book. They took additional trips to explore and further record specific straw-bale buildings that now constitute a new book called Strawbale Plans.

In addition to Wayne’s working with owners and builders on straw-bale home designs and conducting workshops, Colleen and Wayne have put their experience into building this straw-bale home of their own in Teton Valley, Idaho. www.wjbingham.com

by Rene Kilian – Denmark

Save money on your black and grey water while protecting the environment!

Reeds and iris clean the wastewater in the planted filter.

All properties without sewage facilities in rural areas of Europe must meet minimum standards for wastewater treatment. It can be expensive joining on to the main sewage lines. A planted filter’ – a modern kind of reed-bed system with vertical waterflow – has low operating costs and is an inexpensive alternative.

Approximately 30 of these filters have been built in Denmark. The systems are planted with wetland plants, and occupy around 16m² per dwelling.

The system complies with the latest Danish standards, which are stricter than the European standard.

Along with this, environmental impact is reduced and the homeowner can save money on sewage connection and payments.  The investment can be paid for through savings in less than five years, when compared to a standard sewage connection. Here is an example.

Reuse of treated wastewater
Søren Raffnsøe built his own straw-bale house, went about it in a way that was as environmentally and economically friendly as possible. The way that water comes in and out of the house has
been considered in a holistic manner, and is the first of its kind in Denmark.

The house has its own planted filter to treat wastewater. The system is only 8m2 because the house has a composting toilet.

The planted filter is a biological-cleaning system. The system, designed by René Kilian, is an effective alternative to a sewage connection. The system can even be integrated into a garden where it could resemble a garden bed growing with thatching reeds, iris and bullrushes.

Figure 1. A recycling system with the planted filter where water is reused in the washing machine and garden. 1. Sedimentation Sedimentation tank for grey wastewater only. The source of the water may vary depending on local codes or regulations but might include water from bath, washing machine and kitchen. 2. Pump well with a level controlled pump. 3. Reed bed system or constructed wetland. 4. Tank for treated wastewater and treated rainwater. 5. “Green” pipe for reuse water to washing machine and garden. 6. Water vitalizer in drinking water pipe. 7. Fine filter for treatment of rainwater. 8. Untreated rainwater toward sand catcher and infiltration unit. 9. “Black”’wastewater from toilet to compost container. 10. Urine from toilet to urine container Design by Kilian Water Ltd., Denmark

The recycled water becomes so clean that you can reuse it to flush the toilet, wash clothes and water the garden. As compost toilets don’t use water, Søren uses the water only in his washing machine and garden. See Figure 1.

Along with this, he saves 50 percent in his usage of drinking-quality water. To collect the excess recycled water, he has made a little pond in the garden, where there is an extra cleaning process that created a habitat for plants and animals. The drinking water itself is also special. He has installed a ’vitalizer’ in his drinking water pipes. This revitalizes the water so it attains the same quality as spring water.

Payback in less than five years

A planted filter of 16m2 suitable for a normal household, will cost around 60,000 Danish kroner/$11,083.80 USD. Connection to public sewage costs one household around 40,000 kroner/$7,389.21 USD. The investment can be paid back in less than five years, as you can save on annual wastewater bill payments. Ongoing costs for a planted filter are 0 kroner /m3; there is just a government tax of 1.60 kroner /m3. Costs for sewage are approximately 35 kroner /m3. This means a dífference of nearly 33.50 kroner / m3. With an average consumption of 170m3 per year, a household would save around 5,700 kroner/$1,052.96 USD per year, or 140,000 kroner/$25,862.20 USD after 25 years.

The planted filter at 8m2 in front of the newly built straw-bale house.

If you chose a reuse system in addition to this, and saved 50 percent on water consumption, you save 7,000 kroner/$1,293.11 USD per year. After 25 years, you will have saved 175,000 kroner /$32,327.80 USD. With the correct wastewater solution, you can really save money and protect the environment.

This article does not appear in The Last Straw and is original content.

Prepared by Joyce Coppinger, Managing Editor/Publisher, The Last Straw Journal

402.483.5135, <thelaststraw@thelaststraw.org> www.thelaststraw.org

INSULATION

The R-value used for straw-bale walls is R-30. Most conventional stick-built construction has an R-value of around 15 with as high as R-30 in ceilings.

Testing under controlled conditions allows the researcher to estimate the thermal resistance to heat flow through the material. This is expressed as an R-value. (R = resistance) R-value is the inverse of U-factor, or conductivity. U-factor is a measure of Btu/(hr. s.f. °F), or British thermal units per hour, per square foot of material, per degree Fahrenheit of temperature difference between the two sides of the material.

Conclusions from the document Thermal Performance of Straw Bale Wall Systems available at www.ecobuildnetwork.org/strawbale.htm

Tests have shown a range of values from R-17 (for an 18-in. bale wall) to R-65 (for a 23-in. bale).

Analysis at Oak Ridge National Lab, among other places, has shown that R-values for insulation materials used in standard walls are generally much higher than the R-value for the wall as an assembly of disparate materials. Joe McCabe recently postulated that the same phenomenon could account for the difference between the high values from his testing of bales and the lower values obtained in the 1998 Oak Ridge test of a straw-bale wall system. While it is possible that the relatively low densities where bales abut each other might contribute to greater heat loss than would be measured through an individual bale, it is unlikely that this would account for the entire difference. This difference between bales and bale walls is nothing like the difference between standard insulation and what is found in stud framed walls (insulation voids, thermal bridges, uninsulated headers, and other faults).

It is noteworthy that all tests of straw-bale wall systems prior to the Oak Ridge test in 1998 had potentially significant shortcomings and should not be considered particularly reliable. The last Oak Ridge test had no identified deficiencies and is considered by most to be an accurate determination of the thermal resistance of straw-bale walls. ORNL determined the R-value to be R-27.5 (or R-1.45/inch), or R-33 for three string (23-in.) bale wall systems. Shaving a bit off the top just for conservatism’s sake, the California Energy Commission officially regards a plastered straw-bale wall to have an R-value of 30.

A final note is a reiteration of a point made earlier: it matters little whether the final truth about the R-value of straw bales walls is R-33 or R-43 or even R-53. Above R-30, the differences are minor and will usually be overshadowed by windows, floors, doors and ceiling/roof details.

Whatever the value, it is at least three times better than the average -in.R-19-in. wood stud-wall system.

FIRE

In July 2006, the Ecological Building Network in California funded and oversaw the following ASTM E119-05a – Straw Bale Fire Tests done in Texas. Both walls withstood the fire and hose stream tests, as described below.

(Documents are available at www.ecobuildnetwork.org/strawbale.htm)

One-hour Fire Resistance of a Non-Loadbearing Wall w/ Earth-Plaster Coating.

A 12 ft x 14 ft non-loadbearing wall constructed with 7.5 pcf rectangular wheat straw bales stacked in a running-bond pattern, clad on each surface with 1-inch of earthen-plaster, produced, assembled and tested as described in the documentation, successfully met the conditions of acceptance as outlined in ASTM Method E119-05a Fire Tests of Building Construction and Materials for a fire endurance rating of one hour.

Two-hour Fire Resistance of a Non-Loadbearing Wall w/ Cement-Stucco Coating.

A 10 ft x 10 ft non-loadbearing wall constructed with 7.5 pcf rectangular wheat straw bales stacked in a running-bond pattern, clad on each surface with 17 GA stucco netting and 1-inch of cement/stucco, produced, assembled and tested as described in the documentation, successfully met the conditions of acceptance in ASTM Method E119-05a Fire Tests of Building Construction and Materials for a fire endurance rating of two hours.

The EcoBuilding Network’s Board of Directors is currently Ann Edminster (Pacifica, California) Architect, author of Efficient Wood Use in Residential Construction-in., and co-chair of the development committee for LEED(TM) Residential standards.

Bruce King (San Rafael, California) Director, Founder, Structural Engineer, author of Buildings of Earth and Straw-in. (1996), -Making Better Concrete-in. (2005), and Design of Straw Bale Buildings-in. (2006); Sarah Weller King (San Rafael, California) Secretary and Treasurer Peter Loafer (Boulder, Colorado) Attorney and property developer; Drew Moran (Palo Alto, California) President, Drew Moran Construction; Anne Tilt (Berkeley, California) Architect and partner, Akin-Tilt Architects; Carol Vilonia (Santa Rosa, California) Architect, contributing columnist for Natural Home magazine, co-author of Natural Home Remodeling (2006).

MOISTURE

From House of Straw – Straw Bale Construction Comes of Age, U.S. Department of Energy, Energy Efficiency and Renewable Energy, April 1995. www.eren.doe.gov/buildings/documents/strawbale.html

Will the bales rot? Without adequate safeguards, rot can occur. The most important safeguard is to buy dry bales.

Paint for interior and exterior wall surfaces should be permeable to water vapor so that moisture doesn’t get trapped inside the wall. Construction design must prevent water from gathering where the first course of bales meets the foundation. Even if straw bales are plastered, the foundation upon which the bales rest should be elevated above outside ground level by at least six inches or more. This protects bales from rainwater splashing off the roof.

From Moisture properties of straw and plaster/straw assemblies by Dr. John Straube in Canada as a result of testing done there. John holds a joint appointment as Associate Professor in both the Department of Civil Engineering and the School of Architecture at the University of Waterloo and teaches courses in structural design, material science, and building science to both disciplines. At the university, John is also the director of the Building Engineering Group. John is a founding principal of Building Science Consulting, a frequent contributor to buildingscience.com.

Based on the test data and literature review, several conclusions can be drawn:

1. A 450 mm (18-in.) thick straw bale should have a vapor permeance of approximately 110 to 220 ng/ Pa•s•m2 (2 to 4 US perms).

2. Cement: sand stuccos are relatively vapour impermeable. In fact a 38 mm (1.5-in.) thick cement : sand stucco may act as a vapor barrier (i.e., have a permeance of less than 1 US Perm).

3. The addition of lime to a cement stucco mix increases permeance. As the proportion of lime is increased, the permeance increases. Pure lime: sand stuccos are very vapor permeable. The permeance of a 38 mm (1.5-in.) thick cement : sand stucco can be increased to 5 or 10 US Perms by replacing half the cement with lime and to 15 to 30 US Perms by using a pure lime : sand stucco. The addition of even a small amount of lime (0.2 parts) may increase the permeance of cement stucco dramatically (e.g., from under 1 to 3 to 6 US Perms).

4. Earth plasters are generally more permeable than even lime plasters. The addition of straw increases the permeability further. A 38 mm (1.5-in.) thick earth plaster can have a permeance of over 1200 metric perms (over 20 US Perms), in the same order as building papers and house wraps.

5. Applying an oil paint to a moderately permeable 1:1:6 stucco will provide a permeance of less than 60 metric perms (1 US perms) and thus meet the code requirements of a vapour barrier.

6. Earth plasters were not found to have significantly different water absorption than cement and lime stuccos. The earth plasters, regardless of density and straw content, resisted 24 hour of constant wetting easily, although the topmost 1/8-in. of surface became quite muddy. In a real rainstorm this behavior may cause erosion.

7. Lime washes appear to be somewhat useful for reducing water absorption while not reducing vapor permeance. The lime wash over earth plaster did not dramatically lower water absorption but will increase the mechanical strength of the plaster after wetting, i.e., they will increase the resistance to rain erosion.

8. Based on Minke’s and Straube’s earlier tests, siloxane appears to have little or no effect on the vapor permeance of cement, cement:lime, lime, and Moisture Properties of Plaster and Stucco for Strawbale Buildings EBNet BalancedSolutions.com 34 earth plasters while almost eliminating water absorption. The use of siloxane can be recommended based on these earlier tests.

9. Sodium silicate did not seem to have much impact on water uptake or vapor permeance. This additive may hold earth plaster together, or increase its erosion resistance, but as tested it had no noticeable impact on moisture properties.

10. Linseed oil at 2% in an earth plaster mix is not a very effective water repellent and does act to restrict vapor permeance somewhat. It may add some strength to an earth plaster in the wet state. Heavy applications of linseed oil to the surface of finished earth plaster will, based on Minke’s tests, reduce the water absorption to almost zero, but will markedly decrease vapor permeance.

11. The test methods described here appear to provide repeatable results, and in general compare well to previous tests on different samples by both the same (Straube) and different researchers (Minke).

Gernot Minke founded the Research Laboratory for Experimental Building at Kassel University in Germany in 1974, studying straw-bale construction and other sustainable building techniques, low-energy and passive house construction, and green roofs. He is also an independent architect and adviser for building ecology.

The full article can be accessed at the EcoBuilding Network’s web site www.ecobuildnetwork.org/strawbale.htm

INSECTS, VARMINTS AND VERMIN

Will the bales rot? Without adequate safeguards, rot can occur. The most important safeguard is to buy dry bales. Fungi and mites can live in wet straw, so it’s best to buy the straw when it’s dry and keep it dry until it is safely sealed into the walls.

Paint for interior and exterior wall surfaces should be permeable to water vapor so that moisture doesn’t get trapped inside the wall. Construction design must prevent water from gathering where the first course of bales meets the foundation. Even if straw bales are plastered, the foundation upon which the bales rest should be elevated above outside ground level by at least six inches or more. This protects bales from rainwater splashing off the roof.

Will pests destroy the walls? Straw bales provide fewer havens for pests such as insects and vermin than conventional wood framing. Once plastered, any chance of access is eliminated.

House of Straw – Straw Bale Construction Comes of Age, U.S. Department of Energy, Energy Efficiency and Renewable Energy,

April 1995

www.eren.doe.gov/buildings/documents/strawbale.html

CODES

There are provisions within the building codes that allow building with bales. David Eisenberg, Development Center for Appropriate Technology (DCAT) in Tucson, Arizona (www.dcat.net), shares these citations from codes that pertain to straw-bale design and construction as an alternative materials, design and methods of construction and equipment. David has been involved with codes issues related to strawbale and other natural building materials and methods for 15 years or more, and as a member of the board of UBC, USGBC and other organizations working with building codes and green building programs.

You can use this information to answer questions codes officials and other regulatory agencies may have.

From the 2003 International Energy Conservation Code (IECC)

SECTION 103

ALTERNATE MATERIALS — METHOD OF CONSTRUCTION, DESIGN OR INSULATING SYSTEMS

103.1 General. The provisions of this code are not intended to prevent the use of any material, method of construction, design or insulating system not specifically prescribed herein, provided that such construction, design or insulating system has been approved by the code official as meeting the intent of the code. Compliance with specific provisions of this code shall be determined through the use of computer software, worksheets, compliance manuals and other similar materials when they have been approved by the code official as meeting the intent of this code.

From the 2006 IECC

SECTION 103

ALTERNATE MATERIALS — METHOD OF CONSTRUCTION, DESIGN OR INSULATING SYSTEMS

103.1 General. This code is not intended to prevent the use of any material, method of construction, design or insulating system not specifically prescribed herein, provided that such construction, design or insulating system has been approved by the code official as meeting the intent of this code. 103.1.1 Above code programs. The code official or other authority having jurisdiction shall be permitted to deem a national, state or local energy efficiency program to exceed the energy efficiency required by this code. Buildings approved in writing by such an energy efficiency program shall be considered in compliance with this code.

From the 2003 International Residential Code (IRC)

R104.11 Alternative materials, design and methods of construction and equipment. The provisions of this code are not intended to prevent the installation of any material or to prohibit any design or method of construction not specifically prescribed by this code, provided that any such alternative has been approved. An alternative material, design or method of construction shall be approved where the building official finds that the proposed design is satisfactory and complies with the intent of the provisions of this code, and that the material, method or work offered is, for the purpose intended, at least the equivalent of that prescribed in this code. Compliance with the specific performance-based provisions of the International Codes in lieu of specific requirements of this code shall also be permitted as an alternate.

R104.11.1 Tests. Whenever there is insufficient evidence of compliance with the provisions of this code, or evidence that a material or method does not conform to the requirements of this code, or in order to substantiate claims for alternative materials or methods, the building official shall have the authority to require tests as evidence of compliance to be made at no expense to the jurisdiction. Test methods shall

be as specified in this code or by other recognized test standards. In the absence of recognized and accepted test methods, the building official shall approve the testing procedures. Tests shall be performed by an approved agency. Reports of such tests shall be retained by the building official for the period required for retention of public

records.

From the 2006 IRC

R104.11 Alternative materials, design and methods of construction and equipment. The provisions of this code are not intended to prevent the installation of any material or to prohibit any design or method of construction not specifically prescribed by this code, provided that any such alternative has been approved. An alternative material, design or method of construction shall be approved where the building official finds that the proposed design is satisfactory and complies with the intent of the provisions of this code, and that the material, method or work offered is, for the purpose intended, at least the equivalent of that prescribed in this code. Compliance with the specific performance-based provisions of the International Codes in lieu of specific requirements of this code shall also be permitted as an alternate.

R104.11.1 Tests. Whenever there is insufficient evidence of compliance with the provisions of this code, or evidence that a material or method does not conform to the requirements of this code, or in order to substantiate claims for alternative materials or methods, the building official shall have the authority to require tests as evidence of compliance to be made at no expense to the jurisdiction. Test methods shall be as specified in this code or by other recognized test standards. In the absence of recognized and accepted test methods, the building official shall approve the testing procedures. Tests shall be performed by an approved agency. Reports of such tests shall be retained by the building official for the period required for retention of public records.

From the 2006 IBC

104.11 Alternative materials, design and methods of construction and equipment. The provisions of this code are not intended to prevent the installation of any material or to prohibit any design or method of construction not specifically prescribed by this code, provided that any such alternative has been approved.

An alternative material, design or method of construction shall be approved where the building official finds that the proposed design is satisfactory and complies with the intent of the provisions of this code, and that the material, method or work offered is, for the purpose intended, at least the equivalent of that prescribed in this code in quality, strength, effectiveness, fire resistance, durability and safety.

104.11.1 Research reports. Supporting data, where necessary to assist in the approval of materials or assemblies not specifically provided for in this code, shall consist of valid research reports from approved sources.

104.11.2 Tests. Whenever there is insufficient evidence of compliance with the provisions of this code, or evidence that a material or method does not conform to the requirements of this code, or in order to substantiate claims for alternative materials or methods, the building official shall have the authority to require tests as evidence of compliance to be made at no expense to the jurisdiction. Test methods shall be as specified in this code or by other recognized test standards. In the absence of recognized and accepted test methods, the building official shall approve the testing procedures. Tests shall be performed by an approved agency. Reports of such tests shall be retained by the building official for the period required for retention of public records.

INSURANCE AND FINANCING

See http://sbregistry.greenbuilder.com – the International Straw Bale Registry sponsored by The Last Straw journal, Greenbuilder.com, Development Center for Appropriate Technology and the Texas straw-bale association as a resource and research database pertaining to straw-bale building, including buildings open for tours and visits, descriptions of design, construction, materials, special features and those who were involved in the building project, including homeowners, owner/builders, insurance, mortgage lenders, builders, architects and others.

When planning and building a straw-bale building, it is best to make contacts early in the process about liability insurance coverage during construction as well as homeowners coverage after the building is completed.

Homeowners insurance is available for straw-bale homes and insurance coverage for other straw-bale buildings is available also. Independent insurance agents and companies may be more likely sources, but many other companies offer homeowners and liability insurance.

Many straw-bale buildings are owner-financed or built on a pay-as-you-go basis, but as strawbale and natural building become more popular and generally accepted many structures have been financed through mortgage lenders, banks, credit unions, state and federal funding for housing, and other sources.

Contact your local sources to determine your best options. You may want to prepare detailed financial calculations and a budget for the project before approaching these groups and institutions. And you will need to be well versed about straw-bale projects in your immediate area, identify comparables from real estate companies, if possible, and have already contacted your local codes official about regulations and permits so that you know the project can be permitted.

This is the second of a two-part article on creating a poured adobe or earth floor. See Earth Floor, TLS#52, for the first article describing how to prepare for and install a poured adobe floor.

By Tom Lander – New Mexico, USA

Now, weeks later after your floor is 100 percent dry, it’s time to seal and fill the floor with Linseed oil. Here in the South West our floors can dry in a matter of a few weeks but in humid climates error on the safe side.

Materials:

Linseed oil. We prefer raw linseed oil, less petroleum additives then the common boiled linseed oil but the boiled works if you are not concerned about petroleum out gassing. Even raw linseed oil has carcinogenic warning labels. Ask for an MSDS sheet. Linseed oil is made from flax seed.

Citrus Solvent (thinner) or mineral spirits, again petroleum out gassing

We are still learning how to estimate coverage and quantity so I’m not sure how much material is needed for your size floor. Maybe buy 2 gallons each for starters; you can buy linseed oil in 5-gallon lots.

Equipment:

4” paintbrushes, natural bristle is always best but pricey

Electric hot plate or gas camp stove

Large pot or kettle

Approved vapor mask

Safety glasses or goggles

Fan for air circulation/expelling fumes if you feel this is necessary

Rags,

Gloves

Prep floor:

Sweep or vacuum any loose debris and dust. You might want to do a light mopping or sponging. Give yourself time for the moisture to dry before applying the oil.

Procedure:

Heat the linseed oil to almost boiling (do not boil). We are just trying to heat the oil to aide in soaking, absorbing in. This must be done outside with caution, flammable. Another option is to pour the oil into a large deep baking pan, cover with a piece of glass and let it sit out in the sun. Leave an air gap. With either method start with a small batch to get the hang of heating and applying.

Transfer the oil into a suitable container. You can paint the material on or if you are quick, you can pour some onto the floor and swoosh it around with the brush. The only risk here is that you will not get an even distribution of material. Try it. Be consistent and watch how the floor is absorbing. If more than one person is applying, then you might get varying results but by the time you are done it shouldn’t matter. Use up your first small amount then decide how much more (a large batch) to heat for your next go at it. For reference keep track of how much material you use for each coat and offer this info to others.

The floor will soak up this first coat and there should not be any pooling of the oil on the surface. Plan your route of attack so you end up working yourself out the door, window or hallway. You should be able to go back to the start and do a second full strength coat right a way. Remember your shoes will be picking up dirt and dust from the outside so take steps to minimize this. There are disposable booties one can buy to cover their shoes.

What we are trying to do is seal the floor but think of it more like filling the floor. Filling all the little air voids between the sand and clay particles with oil.

The floor will dictate the timing and how much material. Watch how the material soaks in. You might be able to continue with more heated, thinned coats the same day, unless you are tired or sick from the fumes and not wearing a vapor mask.

Diluting:

The first two coats can be applied full strength. For the third and fourth coat combine 75% oil with 25% thinner, heat and apply. Watch the absorption, watch for pooling or puddling but also give the material some time to soak in; you just don’t want it to dry on the surface. Have a rag and thinner handy to wipe up any excess otherwise the material dries on the floor and becomes sticky. If this happens then it’s quite a job to use thinner and rags to clean the floor. Apply at least two coats of this first diluted mix.

Next is a 50% to 50% heated mix. Hopefully by now you have learned if pouring and brushing works for you (certainly faster) or just brushing or maybe it’s time now to just brush. Isn’t this fun learning as you go? Like all earthen materials, they tell you when and what to do, what’s the word? Experience.

Remember, oily rags and brushes are flammable so hang out to dry and do not leave a pile of rags unless it’s in the middle of a gravel driveway and you want to have some fun.

www.bioshieldpaint.com

Sunny Side http://www.gillroys.com

This article appeared in TLS #59

by Tim Beatley – Virginia, USA
Reprinted with permission from Residential Architect magazine, November 2005.

We live in disconnected times. We occupy space but know little about it. Instead of joining communities or neighborhoods, we buy houses and make real estate investments.

Sustainable design offers us the chance to rekindle these lost connections, to rebuild knowledge of place. New residential development is commonly thought to bring more cars and traffic, higher taxes, overcrowded schools, diminished views, and open spaces. But there is a way to turn this around – if we can imagine new growth connecting with and strengthening our sense of place. This kind of green design might take many forms, but just a few possibilities are mentioned here.

Acting locally

One idea is to locally source building materials. In our globalized economy, such materials can originate hundreds or thousands of miles away from where they are eventually installed or assembled. They contain a high embodied energy, and their extraction often entails substantial ecological impact. Paradoxically, much of the practice of green building has emphasized materials, such as bamboo flooring, that are transported great distances.

We need to look much closer to home, to materials that nurture local livelihoods and reconnect us to place and land. An innovative sustainable wood initiative here in Virginia holds some clues and offers some inspiration. Operated by Appalachian Sustainable Development (ASD), it supports the local economy by working with small wood-lot owners who are willing to manage and harvest sustainably. The wood produced is beautiful, durable, and distinctive (more of the tree is used, with knotty “character” wood a key result), and it is certified under ASD’s Sustainable Wood label. It is then dried in a solar- and wood-waste-powered kiln and cut into flooring at ASD’s mill.

My family and I recently installed ASDcertified white-ash flooring in our home. As a result, I know where the wood was grown, and I have some assurance that the result for the landscape is not destructive but rather restorative. In this case, a sustainable material close to home was actually less expensive than its standard commercial alternative. It is a small expression of commitment to
sustainability but an important step on the way to a deeper connection and duty to place.

Using local materials is a growing practice in sustainable design communities. Innovative green projects like BedZED, the Beddington Zero Energy Development in the London borough of Sutton, have explicit targets for local materials. At BedZED, more than half of the building materials arrive from sources within a 35-mile radius of the site. Wood siding comes from local municipal forests, bricks from a local brick company.

In Western Australia, there has been a creative effort to nurture furniture building and wood artistry. Rather than exporting logs (or allowing them to be converted to low-value wood chips and then exported), there is a growing sentiment that these resources can be the foundation of a highvalue-added, labor-intensive economy, of which sustainably managed forests can serve as a linchpin. Among other steps, a forest heritage center and school of fine furniture making has been established there, and the number of outlets for locally made wood products and crafts is growing.

Much of our food comes from very far away. It typically travels some 1,500 miles from where it is grown to where it is eaten, according to the 2001 report “Food, Fuel, and Freeways,” and we are usually oblivious to these origins. New developments could begin to think more carefully about the food needs of their future residents, perhaps developing long-term relationships with local growers. This is essentially the concept of Community Supported Agriculture (CSA) residents buy a share in a local farm that provides (often delivered) a basket or box full of produce each week during the growing season. CSA farms are growing in popularity – there are now more than 1,500 of them nationally – and they could be offered as part of the package that goes along with a new home (or at least as an option).

Designing in opportunities to grow food directly is another way of promoting sustainability (and healthier living), strengthening place, and re-earthing us. This is a trend in Europe, where ecological, mixed-use projects such as Viikki in Helsinki, Finland, have left green fingers between major buildings for garden plots. Single-family homes might be designed to facilitate this as well. A model sustainable home in the Perth, Australia, suburb of Subiaco, for instance, includes extensive edible landscaping and a built-in raised-bed vegetable garden in its backyard. The garden is large enough to produce all the vegetables a typical family needs.

Energy use is another way to reconnect with local places. Every place has opportunities to generate its own power, whether through wind, sunlight, or biomass. Strong European examples exist of communities that have been able to redirect community resources to local energy production. In Aeroe Island, Denmark, which aspires to be 100 percent energy independent, small power plants generate energy from the sun and from locally grown straw and hay. Expenditures for energy stay local and help to strengthen, not diminish, the region’s economy.

A more urban example is the redeveloped district of Vastra Hamnen in Malmo, Sweden, where a variety of renewable energy technologies and design ideas have been incorporated into dense housing and the ambitious goal of 100 percent renewable energy from local sources has been met.  Energy production is a visible element of the community, with vertical solar hot-water-heating panels feeding into a district heating grid.

BedZED again offers inspiration with an on-site combined-heat-and power plant fueled by wood waste from tree trimmings. In Freiburg, Germany, the Solar-Fabrik solar-technology factory burns oil from locally grown rapeseed in a carbon-neutral cycle, further demonstrating the power of combining green and local.

The energy consumed by residents and the embodied energy associated with new building materials might also be compensated for in ways that creatively restore and renew bioregions. In the U.K., the Carbon Neutral Company works with banks and building societies to offer a carbon neutral mortgage, which provides for the planting of enough trees to cover the carbon footprint of the home and lifestyle of its occupants. In Australia, similarly, several banks are now offering carbon-neutral car loans. Habitat and place restoration can happen in many ways, of course, but local tree planting holds potential for productively harnessing the green sensibilities of people on behalf of place.

In an increasingly turbulent and globalized world, rebuilding lost place and human connections in a host of creative ways provides solace, strength, and reassurance. Sustainable design must strive not only to reduce its overall ecological impact, but to do so in ways that enable us to be truly native to place.

Resources
Residential Architect magazine www.residentialarchitect.com

Appalachian Sustainable Development
www.asdevelop.org/sustainable_woods.html

www.bedzed.org.uk
Beddington Zero Energy Development, an environmentallyfriendly,
energy-efficient mix of housing and work space in
Beddington, Sutton, United Kingdom.

Viikki Eco Neighbourhood Blocks – Finland
www.cardiff.ac.uk/archi/programmes/cost8/case/holistic/viikki.html

Malmo, Sweden
naturalspace.com_broadband/swedentext.htm
The CarbonNeutral Company, United Kingdom
www.carbonneutral.com/pages/reducingCO2.asp

Sustainable Communities

Toward Sustainable Communities: Resources for Citizens and
Their Governments by Mark Roseland, Sean Connelly, David Hendrickson and Chris Lindberg.

Developing Sustainable Planned Communities by Richard
Franko, Jo Allen Gause, Jim Heid, and Steven Kellenberg.

Sustainable Communities: The Potential for Eco-neighbourhoods
by Hugh Barton.

Designing Sustainable Communities: Learning from Village
Homes by Michael Corbett, Judy Corbett, and Robert L. Thayer.

Fostering Sustainable Behavior: An Introduction to Communitybased
Social Marketing by Doug McKenzie-Mohr and William Smith.

Ecovillages: A Practical Guide to Sustainable Communities
by Jan Martin Bang.

Sustainable Communities: Learning from the Cohousing
Model by Grahm Meltzer.

Green Cities: A Guide for Sustainable Community Development
by Michael Bloomfield and Michael Lithgow.

Sustainable Communities Network www.sustainable.org
Links citizens to the resources they need to implement innovative processes/programs.

Intentional Communities www.ic.org
Information on ecovillages, cohousing, intentional communities, urban housing cooperatives and other related projects.

School of Living www.schoolofliving.org
Nurturing healthy, Community Land Trust Communities.

New Urbanism www.newurbanism.org
Many choices for living in more sustainable, convenient and comfortable places.

Tim Beatley is the Teresa Heinz Professor of Sustainable Communities at the University of Virginia. This article is based, in part, on ideas discussed in his book Native to Nowhere: Sustaining Home and Community in a Global Age (Island Press, 2004).
www.residentialarchitect.com

This article appeared in TLS #59.

Turko Semmes is a licensed general contractor from San Luis Obispo County, California, and one of the foremost experts in straw-bale building techniques.

A graduate from the Architecture Department of Cal Poly State University in 1978 with a degree in Construction Engineering, he has been self-employed since that time, running a custom home building business specializing in energy efficiency and sustainable building techniques. Turko is a co-founder of the California Straw Building Association. He has built several custom homes, agricultural buildings, and wineries throughout central California. He has taught classes and workshops on sustainable building systems to community groups and to students at the elementary, secondary, and university level. He is recognized as an expert on passive solar design concepts and other energy efficient techniques, as well as nontoxic and sustainable building materials.

The Semmes southwest-style straw-bale home (pictured here) is nestled in the Los Padres National Forest in a setting that joins nature with natural building. The courtyard/pool area is an inviting setting filled with flowers and hand-painted artwork at the main entry door leading to Turko’s office and the family den. The lower terrace provides space for relaxing poolside with an outdoor shower nearby. The upper terrace is a covered outdoor cooking and dining area. The formal living and dining rooms and the master bedroom face onto the meadow with views toward the mountains of the Santa Lucia Range. The cool and calming color palette of the master bedroom contrasts with the bright and lively colors of the other living spaces.

Turko Semmes, Semmes & Co. Builders, Inc., Atascadero CA
<turko@semmesco.com> www.semmesco.com
Photo credits: Semmes & Co. Builders, Inc.

by Ken Haggard and Polly Cooper – California, USA

Adopted from an article that appeared in Home Power Magazine.

Straw-bale cottage during construction.

Like many other architectural firms in California, San Luis Obispo Sustainability Group architects had been designing building that utilized passive solar for many years. Like many other architectural firms around the country, and around the world, in recent years we found ourselves shifting our design work to “sustainability,” an extension of passive solar design concepts.

The definition of sustainability we use in our work is to use resources that meet our needs but do not compromise the ability of future generations to meet their needs. As our firm and the work we do evolved, our practice has evolved to encompass broader issues including life cycle impacts of materials, miniaturization of infrastructure, health issues in buildings, permaculture and landscape regeneration.

By 1994, we had developed a comfortable working environment, consisting of a mix-used passive solar complex that included an office, shops and a residence on an old trout farm adjacent to the Los Padres National Forest, 12 minutes north of the city of San Luis Obispo. Little did we imagine that we would endure the trauma of losing nearly everything we owned or that this tragedy would afford an opportunity to redevelop our complex based on our new knowledge of sustainability. In August 1994, the 41 Wild Fire that burned 40,000 acres/16,200 hectares in our area destroyed our entire complex, and forced us into applying these broader principles of sustainable design for ourselves. Once we got over the initial shock of losing an extensive library, slide collection, office and home, it became more and more obvious what an opportunity our natural fire-oriented local ecology offered us – we could start from scratch and build sustainably, without the problem associated with retrofitting existing structures.

One of the first things we realized was that the fire had left us with a large inventory of building material. (We had several strawbale benches on the site before the fire. They turned out to be more fire resistant than most of the stucco-, tile- and metal-clad buildings in the canyon.) It had killed most of the mature trees (except for 2/4 of the fire-adapted oaks), and these trees were now available to use as lumber. We would never have dared touch them while they were alive. In addition, the massive opening-up of the landscape afforded by the fire allowed us to examine our aging infrastructure. We realized it could be redone in a much more sustainable way. Landscape regeneration became an everyday reality, not some theoretical subject. We suddenly could do things that we had only talked about, but never had the time to do – like getting off the electrical grid.

Completed straw-bale cottage.

Right after the fire, it was necessary to develop a base of operations – a place to store tools, plan from and live in. We attempted to combine this need with several others, such as providing future retreat for guests and visitors, as well as a demonstration workshop for our senior sustainable design architecture class at Cal Poly State University. The result was a 500 sf/46m2 cottage that we uilt on a slab that was left from a shed we had removed long ago. his was one of the few slabs in the canyon not destroyed by the re, because it supported no flammable building at the time. For the structure of this building, we used fire-damaged telephone polls with a truss joist frame. We built the walls from rice straw bales laid on edge, which provide good insulation. In addition, the stucco finish provides interior distributed thermal mass. For the ceiling, we used wheat straw bales laid flat between TJI rafters, which also provide good insulation. The roof is corrugated steel sheet, and includes a 4-ft.x 8-ft/1.2mx3.4m skylight with skylid (movable insulation) unit. Our electrical power came from a Pelton wheel (a microhydro system) on the creek connected to storage batteries.

The construction of this building used healthier building materials that produced less waste. The unused straw was used for erosion control on the site. The building also gets much of its heat from the sun, and uses waste as a resource. In addition, the structure served as a prototype to test details that we planned to use in the larger buildings.

Sustainable Materials

In sustainable design circles, there is a lot of talk about the advantages of using regional materials. As practitioners, we always had nagging doubts about how much of this is truth and how much is idealized theory. Once construction of the guest cottage was underway, we turned our attention to testing this theory. There were several stands of mature trees on the site, especially in the creek areas. The oaks, Sargent cypress and several pine species were native. The Douglas fir and redwoods were not, although their natural range on the coast extends to just 10 miles/48 km north of the site. They were planted 33 years ago when the trout pods were developed. After the fire, all the redwoods put our new growth immediately, and three-quarters of the oaks sprouted from at least part of the remaining trunks. The other trees were killed. We now had an opportunity to do what passive solar applications do – use resources directly on the site rather than importing them from far away and exporting the impact elsewhere.

We felt obligated to mill the dead trees into lumber for reconstruction. We hired sawyers to do this during the fall of 1994, suing a wood Miser portable mill. Both we and the sawyers were amazed at the quantity and quality of wood produced in this relatively small area. We harvested 22,000 board feet of lumber, enough for construction of the other buildings with enough left over to be a storage, rain and sun protection chore. The economics of this also created the unusual condition of using straw-bale construction in conjunction with heavy timber construction, as it was more economical to mill big pieces rather than small ones.

The result of this experience was very interesting. The wood we obtained cost about the same as it would have from a lumberyard, but the quality was much higher. In addition, all phases of the life cycle of this material – source, transport, processing, use and source regeneration – happened on the site. Waste could not be exported elsewhere. It became a resource used for erosion control and organic matter for the regenerative process.

It became obvious to us that although the first costs of both milling our own lumber and buying it from a lumber yard were about the same, the long-range environmental costs of milling our own was much less. These costs are not often accounted for in our present economic system.

The Studio/Office

The next step was construction of the studio and office, completed at the end of March 1995. Because of the function of this building, we placed great emphasis on natural lighting in addition to the passive solar design. The studio/office is also off-grid, poweredby photovoltaic (PV) panels over the library/research area, with a Pelton wheel on the adjacent creek for use as backup in the winter when the water is high. (Two streams fed by the nearby mountain range flow through the property.) The studio/office is heavy timber-frame construction with straw-bale infill.

The south side of the office is configured to allow maximum sun
penetration in the winter and begins to shade itself in early April. During the summer months, it is totally in shade, picking up sun again in late September. Parts of this facade are view windows, part unvented 12-in./30cm Trombe walls that also act as shear walls, and part 9-inch-thick/23cm water tanks below the south-facing window on each end that act as indirect gain passive heaters. The Trombe walls and water tanks are painted with a selective surface paint on the sun-facing side.
The wiggly light shelf on this south facade serves two purposes: providing summer shading of the windows and low water tanks and throwing light deeper into the building in winter. This office is also designed for maximum night ventilation. Summer breezes generally flow from southwest to northeast, so the air moves through the long dimension of the office. These breezes, coupled with the large amount of distributed thermal mass in the building, keeps the interior temperatures below 79oF/26oC, even when daytime summer temperatures are quite hot, occasionally reaching 110oF/43oC.

The Residence

The two-story residence of the complex was completed in October 1997. We used construction techniques similar to those in the office, except that the heavy timber structure is placed 6 in./15cm inside the straw-bale walls. This configuration allowed us to expose the beautiful timber frame and create a continuous two-story straw-bale wall without interruption of the north side. The curves of this wall were very easy to achieve with straw bales without any added expense. This is the best arrangement of the timber structure and bale walls we’ve found to date. There are remarkably few cracks in this wall. The contrast to the stuccoed wood shear walls on the east side is very telling.

The residence uses interior 8-in./20cm concrete block walls as shear walls, thermal mass and decorate “gates.” Besides south-facing glass, skylights provide direct gain, with skylids as thermal control. We’ve found that this system offers more flexibility in the fall and spring than fixed overhangs.  The El Nino weather pattern sometimes produces a very unusual cool late spring, which we cannot respond to in the studio with its fixed overhangs. The skylight/skylid arrangement in the residence did allow us to respond to these unusual climatic conditions. The residence is also off-grid, powered by the PV system and Pelton wheel backup that provides electricity to the rest of the complex.

Landscape Regeneration

One of the unexpected joys of this whole ordeal has been to experience the rapid regeneration of the landscape following the fire. Fire is such an integral part of the native California landscape that everything is set up for it. The first spring was dominated by delicate fire poppies, which only appear in newly burned areas. In this case the seeds had been waiting 60 years for their chance – it had been that long since this area last burned. The next year was dominated by morning glories, which spread all over the armature of the burned branches of earlier plants. The third year was the year of low herbal plants – sages, bush poppies, soap roots and others. In the fourth year, we found the Ceonothus (wild lilac) dominating. The regeneration of oak and cypress trees then began to be much more noticeable.

The best wood for reconstruction turned out to be the Sargent cypress, used for the structure and trim. Alder was the best for cabinets. The cypress trees regenerated naturally because they were a fire species whose seeds are stimulated when they are burned. When the office was done, to commemorate the wonderful alder cabinet it contains, we planted several times the number of alders in the creek than were there before the fire.

Better Quality, Ecological Correctness

We’ve found that the application of our design theories to our own situation has helped convince clients and others that sustainability is more than just another theory. It is a way of achieving better value while simultaneously having far less impact on our planet. In fact, once we get beyond the fears of scarcity that haunt our industrial culture, we will see that these two values – better quality and ecological correctness – are interrelated.

Ken Haggard and Polly Cooper are principals with the San Luis Obispo Sustainability Group, 16550 Oracle Oak, Santa Margarita, California 93453; 805.438.4452, fax 805.428.4680 <slosg@slonet.org> www.slosustainability.com

Ed.Note – An article about the curved wall straw-bale workshop building (not pictured in this issue) at Ken and Polly’s complex will be included in TLS#60/Details, Details, Details. It’s amazing in its design and structure.