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

Loose Strings: Technical Discussions
by Jeff Ruppert – Colorado, USA
T e c h T i p s

A little known fact in the bale building realm is that a handful of people scattered across different continents have experimented with the idea of finishing their bale walls with wood or some type of manufactured siding. The technical term for siding over a bale wall assembly is a “rain screen.” The use of a rain screen (sometimes referred to a “multiple defense assembly”) on a bale wall plays the role of keeping rainwater off of the bale portion of the wall. This is in contrast to the standard way of finishing a bale wall with plaster and allowing moisture to come into contact with it on a regular basis (also referred to as “faceseal” walls). In fact, almost all of the literature to date on bale-wall construction makes the assumption that they are faceseal assemblies.

In this article, we are going to take a look at the pros and cons of in-stalling siding over a bale wall. To some people the idea of not having a plaster finish on a bale house would seem weird, mainly due to aesthetic reasons. However, for those who have chosen to use siding, aesthetics take a backseat to function due to high rates of rainfall throughout the year, as well as constant high humidity. The option of allowing bale walls to even get wet in the first place is not an option and therefore other systems must be considered.

For those of us who live in drier climates, the consideration of moisture is not as dire, therefore giving us more choices. However, doesn’t the siding option make sense if you are concerned about moisture at all? If you would like to design a building with mixed finishes, such as a combination of plaster, masonry and siding, this would open up the opportunity to include bale walls as an option on those projects. In fact, by installing a rain screen over bale walls are we not greatly reducing the potential for moisture damage, as David Eisenberg puts it, by “designing problems out of the project” from the start? We will explore these issues and hopefully offer you another choice in your search for solutions.

Rain Screens
In the old days, a rain screen was simply an exo-barrier that was attached to a building to catch rainwater and shed it before it could hit the structure behind it. The Norwegians titled this approach the “open-jointed barn technique,” since originally it was used in conjunction with the construction of barns¹.

With tighter construction and newer forms of finishes, the technology of rain screens has evolved into a science. One of the advantages of using a rain screen on a bale wall is that, no matter
how you do it, it will probably add a significant layer of protection that would otherwise not exist. This assumes that you do not install the siding to accidentally direct water into the wall. The potential exists for this to happen, so just like any other type of finish, pay attention to the details!

Siding over bale walls

No matter what type of wall you build, the driving forces of moisture will be:

• Air pressure difference (gradient)
• Gravity
• Surface tension
• Capillary action
• Rain drop momentum.

The dominant force acting on your walls will be the difference in air pressure across the siding itself.  As the wind blusters around your house, there are pockets of less and more pressure ever changing within and around your wall assemblies. The main goal is to minimize any pressure differences so water is not accidentally driven into the wall assembly. By minimizing pressure differences, the main force acting on nearby moisture will then be gravity, drawing water down to the ground where it belongs, before it reaches your bales.

In order to equalize pressure, an air gap behind the cladding (siding) needs to be well ventilated to the atmosphere. This can be achieved through different methods, but whatever you do, make sure not to create a gap for wind to blow rain behind the cladding. This means providing ventilation behind the siding so air can pass through easily, but including a barrier at the points of ventilation to keep wind-driven rain from entering.

The advantages of using a rain screen are:

• Adds another option for finishing bale walls (aesthetic),
• Keeps moisture completely off the bale portion of the wall assembly,
• Provides replaceable/changeable finish,
• Has low or no maintenance (depending on material),
• Uses local materials in northern climates near forested areas.

The disadvantages of using a rain screen are:

• Plaster finish is not an option on a bale wall,
• May not be as durable as some types of plaster,
• Materials may not be sustainable or even available in your area,
• Aesthetic of siding may not match your project.

Rain Screen Concept on Bale Walls

It is important to remember that no matter how we finish bale walls, they must be sealed with plaster. This means that even if we choose to use a rain screen, we must apply at least one coat of plaster. One way to install siding on bale walls is to first install nailers for the siding. These can be in the form of 2-in.x2-in. wood strips attached to the sill plate and beam at the top of your bale wall.
We recommend attaching the nailers before stacking the bales, but you can do it afterwards if you like. Once the nailers and bales are in place, one coat of plaster is applied between the nailers. A rough coat of plaster over the bales is all that is necessary. Little or no troweling is required because no one will ever see the results. After plastering, building paper is stapled to the nailers and the siding is then installed, leaving a gap behind the paper for ventilation and drainage.

One issue of concern with this method is the gaps that can occur between the plaster and nailers as the nailer wood shrinks over time. These gaps can allow air to ?ow in and out of the bale wall, creating a loss of insulating value, as well as a path for insects and/or rodents. Extra care and/or the application of caulk can take care of these gaps. Also, these gaps can be eliminated if the nailers are installed after plaster is applied. Whatever you do, be sure that a gap remains between the back of the siding and the plaster.

This is but one way to install siding on to a bale wall. There are variations to this concept, but the goals remain the same – keeping rainwater and back-splash off your bale walls. Pay attention to the details and remember the forces that are acting on water that comes into contact with your walls. Holding these basic concepts in mind will help you design your wall system. And most important, do your homework first!

Happy wall building!

Resources
1. Rainscreen Cladding: A Guide to Design Principles and Practice.Anderson, J.M. & Gill, J.R. Butterworth-Heinemann, 1988.
www.shildan.com/Rainscreen/History.htmlhttp://irc.nrc-cnrc.gc.ca/pubs/ctus/17_e.htmlwww.greenhomebuilding.com/pdf/RainScreen.pdfwww.cmhc-schl.gc.ca/en/inpr/bude/himu/coedar/loader.cfm?url=/commonspot/security/get?le.cfm&PageID=70139

Ed.Note: Jeff encourages TLS readers to send in questions and comments to The Last Straw. There may be outstanding issues that builders are dealing with that most laypeople may not aware of. There are always many questions from people new to straw-bale construction. With this in mind, this column is offered and intended to encourage everyone to educate themselves to the fullest extent regarding building construction, and we are here to help in any way we can. This forum endeavors to offer the best of our knowledge, with no claim to its completeness, but to the spirit of bale building as a continuing evolution of one form of habitat within the larger realm of natural building. We offer this forum for dialogue, with no implication of being right or wrong. This forum is for you, the learner, artisan and teacher.

Jeff Ruppert, P.E., Principal, Odisea LLC, Ecological Building, Engineering and Consulting, P.O. Box 1505, Paonia CO 81428, 970.948.5744  <jeff@odiseanet.com> www.odiseanet.com
Jeff has been in the construction trades for over 25 years, beginning as a laborer and draftsman on his father’s construction projects. He has spent many years working on construction projects he designs, and is a licensed engineer in Colorado.

by Habib John Gonzalez – British Columbia, Canada

This article appeared in a slightly longer version in TLS#22/Spring 1998.

Here are the simple steps and materials needed to build your own bale wall moisture sensor:

1. Determine what depth of the bale you want to monitor and cut the 3/4-inch PVC pipe to that length.

2. Make the white pine sensor disk 1/8-in. thick to fit snugly into one end of the pipe.

3. Solder two lengths of telephone wire to two pairs of small bolts. One end of the pair of wires is bolted to a PVC pipe cap so the tips will protrude from the finished interior wall. The other end of the wires will be bolted to the sensor disk.

4. Use epoxy to glue the disk to one end of the pipe; run the wires through the pipe and fasten the other pair of bolts to the interior wall end cap. Glue the cap to the pipe.

5. Glue a perforated pipe cap over the sensor end of the pipe.

6. The sensor is ready for installation in the bale wall.

7.The TimberCheck moisture meter is available from www.leevalley.com

8. A number of bale wall moisture studies were sponsored by the Canadian Mortgage and Housing Corporation (CMHC). You can get a summary of all of the CMHC moisture work on their web site www.cmhc-schl.gc.ca/publications/en/rh-pr/tech/dblist.cfm?mode=year.  Scroll down to the bottom of the list for 00-103 (year 2000, document 103) on straw-bale moisture monitoring.

1. Outer end-cap
2. Perforated PVC pipe
3. Wood disk with screws
4. Wires
5. PVC pipe
6. Inner end-cap
7. Screw contacts

This article originally appeared in Issue #54.  This issue includes a table of straw-bale building codes, guidelines and mandates in the U.S., and links to straw-bale codes, guidelines and supporting documentation; and an extensive review of the status of straw-bale codes and permitting throughout the world.

by Sigi Koko – Pennsylvania, USA

The bottom line is that yes, using straw bales for non-loadbearing infill walls meets existing building codes for both residential and commercial structures throughout the United States. Why is this true? Because building codes are not written to exclude new or alternative construction materials and methods. Rather, each building code begins with an inclusive statement such as the following from the CABO 95 Preface:

“…there are construction materials and practices other than listed in this code which are adequate for the purposes intended. These other methods represent either seldom-used systems or performance-type systems which require individual consideration by the professional architect or engineer based on either test data or engineering analysis and are therefore not included herein.”

The intent of building codes to ensure that materials are used safely and suitably, not to limit the use of appropriate materials. The burden of proof is to demonstrate that an alternative construction method meets the intent of the building code for durability, effectiveness, and safety (including fire resistance). This means showing how straw-bale infill wall systems meet the requirements of the building code for insulation value, flame spread, smoke development rating, and fire rating. Demonstrating compliance with the building codes is possible thanks to many pioneers that have dedicated time and money to sponsor third-party ASTM (American Society for Testing and Materials) tests. The results of these tests show that straw-bale wall systems not only meet the building code but, in most cases, surpass the intent of the code compared to standard stud-and-drywall construction.

Several states and counties throughout the U.S. have adopted building code amendments that specifically address straw-bale construction, though most regions do not yet include such provisions. Obtaining a building permit for straw-bale infill in regions without a specific building code is not impossible, but rather entails a non-standard process. The question is not whether you can get a building permit for infill strawbale, but rather how to best communicate with local building officials that strawbale is a viable method of construction that meets the existing building code.

David Eisenberg has written extensively and with great eloquence about how to communicate effectively with building officials, and I encourage anyone wanting more detailed information to review his writings on the topic. I have used the following strategy with success:

1) Schedule a pre-submittal meeting with the permitting official to communicate your intentions to build with strawbale. If they are not already familiar with straw-bale construction, provide printed information and additional resources. (Don’t overload with information unless it is requested; like all busy people, building officials are less likely to review a daunting pile.) Bring to the pre-submittal meeting:

• drawings of the proposed building

• an overview of straw-bale construction (I use “House of Straw: Straw Bale Construction Comes of Age” by the US Department of Energy, available at www.eere.energy.gov)

• copies of ASTM testing data (fire-related ASTM tests are at www.dcat.net)

For the final permit submittal, my experience is that stamped structural drawings greatly facilitate the speed and ease of the permitting process.

2) Remember that your building official is your ally not your adversary, and has the same goal as you: to ensure that what gets built is safely built.Acknowledge your common interest for occupant well being and safety. You will create connection instead of confrontation and open a dialog on how to achieve your common goal.

3) Be informed or hire an advocate that has experience in straw-bale construction, including how to build appropriately in your climate. The building officials will generally have more confidence in your project when they know someone on your team fully understands this non-standard construction technique. At a minimum, be prepared for the following common questions:

• How does your wall system handle liquid water and vapor?
• What is the fire rating and smoke development rating of the wall system?
• Will the straw bales attract pests, such as termites and rodents?
• What is the insulating value of strawbale?
• How is electrical and plumbing installed?

I have to date not experienced any delays during the permitting process using this method of interaction with building officials. Increasingly, I find that building officials already possess some level of knowledge about straw-bale construction, which was not the case in this region of the country (Mid-Atlantic states) even five years ago.

Finally, I would like to address the issue of adopting existing codes and details in different climates. I design structures in a wet, humid climate with hot summers and cold winters. However, many of the now-standard straw-bale details have mostly developed in arid and temperate climates that are not necessarily durable in this mixed climate. For example, I do not recommend using rebar inside a straw-bale wall in a humid climate, since the cold metal creates an artificial dew point inside the straw wall. The result is elevated moisture around the rebar, which can lead to rotting the straw over time. Instead, I recommend external pinning or using materials that are “warm,” such as bamboo. Similarly, pea gravel at the base creates an artificial dew point, as well as creating a thermal break along the entire base of the wall. My point is not that the originally developed details are inadequate, but rather that they are specific to an arid climate. So when adopting codes and details in different regions with different climatic concerns, ensure that what you propose will perform durably in your climate.

Sigi Koko, the founding principal of Down to Earth, a design and consulting firm specializing in natural building, has obtained construction permits for many straw-bale buildings in her area. With a Masters of Architecture and several years of in-the-field construction experience, she has developed written specifications and architectural details for straw-bale and cob construction. www.buildnaturally.com

One of the main reasons for creating this forum is to bring the content of TLS in to real-time so we can discuss what has been written.  We encourage comments even with graphics such as CAD drawings or pictures, or maybe even a video, if it helps get your point across.

If the information you find here is useful, just think what you will find in the print and pdf versions of the publication when you subscribe.  Back issues can also be ordered at The Last Straw website here.

As some of you may know, The Last Straw has fallen behind in it’s publication schedule. The quickest way to make issues available as they are published in the coming weeks and months is to post them in PDF format to the online ordering system on the TLS web site. If you want to switch over to PDFs for your subscription, just contact Joyce at <thelaststraw@thelaststraw.org>.  As of this writing TLS#59 is available in PDF format through the TLS online order system. The print version will be published and mailed as soon as possible. The TLS Team is working on #60. The TLS Editor is working on content for #61/Women in Strawbale and Natural Building, #62/Putting a Project Together, and #63/Commercial and Industrial Buildings of strawbale and natural materials.  We are trying very hard to catch up with the backlog and apologize for the delay.

Thank you for visiting. Feel free to look around.  We hope to see you back here often.  Happy baling!

Questions or suggestions can be directed to admin@thelaststrawblog.org.

Ramp next to pump

Merry Mudders

(Stucco Pumping Iron)

by Habib John Gonzalez – British Columbia, Canada

This article, under the title “Stucco Pumping Iron” appeared in TLS#33 (Plaster special issue). [See note at end of article.]

The system I’ve been using for helping owner/builders stucco their bale homes comes from New Mexico. Folks there hire the stucco pump and operator, rent a big (125 cubic foot per minute) compressor with two 50-ft. lengths of air hose with Chicago fittings, two mortar (paddle type) mixers and enslave seven or more friends to help. Two people run the mixers, one runs (literally) the wheelbarrow, three trowel the mud, and one helps me with the hoses. This method worked well for the projects around here.

Experience shows us that nine to twelve workers make the jobs run smoother, with less burnout from the heavy work of mixing and wheel barrowing the mud. It is easier for the trowellers to keep pace with the spraying if there are more hands to help.

If you hire the four legendary Merry Mudders to mix the materials, we usually spray about 2,000 square feet/185.81 square meter of wall per day. These hard-working apprentices are the building and spraying crew for Sustainable Works.

Since most of the trowellers will be inexperienced and tend to overwork the material to make it look “professionally” finished, there is less stress and work if the owner/builder uses a hand-rubbed finish to the walls. As the brown (second) coat begins to harden, the crew rubs the walls with heavy damp sponges, rubber gloves or burlap rags. The trowel marks are removed and the wall takes on a soft porous “sand” finish, like a traditional adobe building. It is beautiful and easy to do.

The equipment rental, stucco materials costs (use prescreened mortar sand to avoid pebbles jamming the spray nozzle which makes me cranky), and prep work are added to the price of the spraying. I helped an architect friend do his load-bearing cottage in Sandpoint, Idaho, and he calculated his cost was half of a commercial job.

When you have evaluated doing your job this way, please let me know what you decide, and we can take the next step from there.

Masking

An important job before spraying is to mask carefully everything you do not want stuccoed with 2-mil. plastic. Where fine, straight stucco lines are desired around posts, window and door bucks, and such, use duct tape to hold the plastic in place. Otherwise, careful stapling will do.

Sifting

In the 1999 season, we introduced a homemade screen to sift the stucco mix as it pours into the wheelbarrows. Owners build a 2×4 frame, large enough to cover most of a wheelbarrow with a brace in the middle to keep the 1/2-in. hardware cloth (galvanized screen) from collapsing with the weight of the mud. This screen catches rocks, sticks, and dry lumps of unmixed materials before they reach the stucco pump to cause clogging stoppages. This saves heaps of time and work clearing the pump, hose and nozzle. I remain a happy camper without all these dramatic “lock-ups” plugging up the works.

A Ramp

The 18-gallon/68.117-liter hopper on the pump is 32 in./81.28 cm high, so we need a ramp and table for the wheelbarrow operators to be able to dump the mud into the machine.

The ramp is generally 16 ft. long and 20 to 24 in. wide. It is built strong enough to carry an adult and a full wheelbarrow of material – about 400 lbs./181.4kg, depending on how well in shape the operator is. A bale or two placed under the ramp keeps it from flexing as the barrowers run up to the table. The well-braced table is built of 2×4s and scrap plywood, 32 in. high, 32 in. wide and 32 in. long.

Buckets

Have lots of 5-gal./18.92-liter plastic buckets on hand (a dozen or so) to measure sand and water and to soak trowels and sponges at the many work sites along the walls. Additional supplies to make life easier are: eight large cellulose sponges for rubbing the brown coat, at least four heavy wheelbarrows to empty a full load of stucco from each mixer (frees the mixer for immediate refill), and three large heavy-duty garbage cans for water (dipping water for the mix is much faster and accurate than waiting for a garden hose).

Estimating Materials

In stick-frame construction, one bag of mixed stucco covers about 80sf./7.43m2. Stucco covers about 35sf/3.25m2 of bale wall due to the thick layer applied, absorption of material by the fibres and the irregularities of the wall surface. One bag of stucco mix (a commercial cement lime stucco product) has a volume of one cubic foot. Measure the length and height of the exterior and interior walls to determine their total area. This figure is the total area per 1/2-in./1.27-cm coat of stucco.

Divide this figure by 35sf/bag to get the number of bags of cement (or stucco mix) needed per coat (scratch and brown). If you are spraying two coats of stucco, multiply this figure by two.

The first or scratch coat is mixed with sand at a ratio of 3:1.

This converts to shovels of material as follows: one bag of stucco mix equals seven shovels in volume, therefore the scratch coat is mixed with 21 shovels of sand per bag of mix. The second or brown coat is mixed at a ratio of 4:1, or 28 shovels of sand per bag of mix.

To calculate the total amount of sand needed, we use the brown coat ratio and multiply the number of bags of mix by four. This gives us the amount of sand in cubic feet; sand is sold by the cubic yard, so this figure is divided by 27. Order the sand by the next greater dump truck load; if you need 7 cubic yards for the project and the supplier has a 10-yard truck, get 10 yards since sand is cheap and a lot can be lost in dumping, and during building.

During the work, water and sand will be added by pre-measured buckets to keep the density of the mix consistent. This avoids wet mixes running off the walls or dry mixes plugging the pump and hose. Anyone seen randomly adding material to the mixers (i.e., “eyeballing” a little extra water or sand) will be drawn and quartered and then considered for serious punishment!

Cold Weather Work

As the daily temperatures drop in the fall, the experts from the Portland Cement Association say to heat the stucco mix water when the daytime temperatures reach 4oC/39.2oF. The other strategy is to enclose the building while stuccoing and for a few days afterwards.

The PCA Stucco Manual states “Water heated to 130oF to 140o F/54o C to 60o C and combined with cold but unfrozen sand will produce plaster in the 70oF to 100oF/21oC to 38oC temperature range. Heating water to raise the mortar temperature has the effect of accelerating the plaster set which protects against early freezing.”

The water can be heated using a large residential water heater to fill the buckets at the mortar mixers.

Another very useful heater is the propane-fired demand water heater; this only burns fuel when a hot water tap is turned on, there is no tank to be constantly heated. Boche and Paloma are two popular makers of demand water heaters.

A third option is to find an old metal trough or several heavy 45-gal./170.29-liter drums which will be heated by a wood fire below. The warm water will be dipped out by the mixing crew.

To ensure against a cold snap, it is helpful to have enough tarps, plastic sheeting, and similar materials available to hang from the eaves to enclose the whole building. This allows the stucco to cure without the threat of spalding (flaking caused by severe frosts).

Lubrication

Buy two large bottles of Joy dishwashing soap. Old Russian plasterers told us a little bit in each mix acts as a lubricant for the pump and they are right!

A Review of Stucco Options

After reading the stucco handout, a contractor still asked what kind of interior finish I trowel onto the bale homes. Here is my reply: The answer is nothing….we spray and mix, advising the owner/builders of their options.

Many are happy to have the trowelling done as a work party to save money, promote community, spread the SB song, etc. The results are not professional, which is why I encourage clients to do a sponge-rubbed “sand” finish on both exterior and interior walls to remove the less than perfect trowel marks and bring out the soft sand texture. If the clients want something more controlled, then I encourage them to hire a professional plasterer to lead the volunteers; otherwise, we cannot help them and ask them to hire a professional crew.

The work party developed as a way to help the owner/builder around here get the plastering done quickly, to protect their building and make it livable sooner. Some larger homes were taking two years to plaster; one commercial building, built with soft shaggy bales burned (according to the fire chief, the fuzz carried the fire up into the rafters and through the 3,000 sf./278.71m2 roof in 23 minutes). The owner delayed plastering a long time while deciding whether or not to use stucco wire.

One compromise is for us to spray the scratch coat only as a work party; the work is less exacting than the final coats and we leave the site knowing the bale wall surfaces are safe. Several friends have done two work party spray coats with us and followed them with simple gyprock mud, sometimes tinted with latex paint. This interior finish is either satiny smooth or textured to taste.

Another interior finishing variation is to dilute the drywall mud to the consistency of heavy cream, add sand, and brush it on the walls (bale or drywall) to continue the pattern used on the exterior walls. This worked well for matching the texture of the drywall with the bale walls and required no sanding.

In the summer of 2001, a client decided to use colored finishing stucco as the brown coat. We sprayed it on 1/2 in. thick instead of the usual 1/8 in. depth. The results were astonishingly fine. Imasco brand in Canada works well and their Technical Services Department remained silent when we inquired about using their material in this manner. La Habra in the U.S. discourages the practice but clients have opted to use it anyway and with good results. One job cracked a lot on the south wall but I believe it was the result of too few workers rushing and thereby overworking the material.

In the spring of 2003, a client, who works for LeFarge Cement in southern British Columbia, used two cups of Bayer brand ferrous oxide colourant per 90-lb. bag of stucco to colour the brown coat we sprayed on his house. We used a half bag of colour additive for 2,000 sf./185.81m2 of wall area, the walls were given a sponge finish and the result is a soft, earthy red tone.

Resources

For more information on the Bayer Ferrox Pigments, contact Bayer representative Kieren O’Conner at 1.412.777.3180 in Pittsburg, PA.

Another source is Jennifer Cohill in Phoenix, Arizona, at 602.266.0462 or check with your local stucco supplier.

Concretech in Delta, B.C., supplies a full line of concrete colouring products from www.concretech.com or toll free at 877.952.0157.

Habib John Gonzales is director of Sustainable Works, a consultation service, teaching the fundamentals of straw-bale construction in British Columbia, Alberta and the Yukon Territory, Canada. Habib is a pioneer of load-bearing strawbale in western in Canada, and developed a low-cost, homemade moisture meter (see TLS# 22 for plans as well as the article on p. 10 of this issue.) This article, under the title “Stucco Pumping Iron,” appeared in TLS#33 (Plaster issue) – copies are still available as a back issue order or on the TLS #1-40 CD. The original of this article in TLS#33 has additional info on the stucco pumping iron not present in this updated and condensed version.

Habib’s contact info is <habibg@netidea.com> Sustainable Works, 615 Cedar Street Nelson, British Columbia, Canada V1L-2C4 Tel/fax: 250.352.3731

Bale Walls with Clay Slip

Model of the Building

We departed from Denver International Airport on August 16th and flew to Atlanta where we boarded a flight straight to Moscow.  We were greeted at the airport by our Czech cohort and friend Jakub Wihan (Kuba) who speaks enough Russian to translate for us.  Kuba was present on our 2005 trip and was now playing multiple roles.  Not only was he going to be teaching his skills of wall building but he was to also translate for us when he could with his limited Russian.  In 2005 we were escorted by our leader, Alyson Ewald of the Altai Project, who organized and raised the funds for our travel.  While she was still in the capacity of the two latter roles, she was raising a newborn back home in Missouri on Red Earth Farms.  We missed her on this trip but new she was doing something much more important.

We landed in Moscow on August 17, met Kuba and made our way into the city for a long wait (12 hours) until our flight to Siberia.  The temperature was nearly 100 degrees (F) and the humidity was hovering around 90%.  We ate food, exchanged money and slept on the floor of the airport as jet lag caught up to us despite our best efforts to remain alert.  Kuba was fresh from his travel from England so he remained awake while we caught some much needed sleep.  We boarded our flight around 11p on Aug 17 and attempted to sleep during the five hour flight through three time zones to the east.  We landed around 6a on August 18 very tired and happy to see our Altai friend and hosts.

Sill Plates with Coal Slag Insulation

While the region and some of the folks were familiar to us, the project for this trip was different than 2005.  We were asked to help build a gallery/conference building with attached office and kitchen space for the Institute of Architecture and Design in Barnaul on their “Dacha” land which is directly south of Barnaul about 20 kilometers as the crow flies (If you have Google Earth installed you can see it here).  The building was designed by the architecture students over the past couple years as an ongoing project within their curriculum.  The result was a beautiful building using straw bale walls that stood about 14 feet tall.  The design of the building incorporated large overhangs and wrap around porches to protect the walls from the harsh winter conditions of Siberia.  To say that we were impressed with the design would be an understatement.  We thought it was magnificent, but we had doubts as to our ability to tackle all of the work needed for the walls, and then have a roof installed.  Our Siberian friends would astound us with their abilities and hard work, but more of that later.

After landing in Barnaul we spent the next few days attending and participating in a seminar for many of the Institute’s important administrators and local officials, we traveled into Barnaul for an art exhibit by one of the students who was also one of our translators, and we visited family of one of the professors and ate dinner.  We spent these days talking with Lena and Sergei, our main hosts and the Deans of the Institute directing the project, about building details and what materials we would need.  There were already bales on the site and the foundation was freshly poured.  There was no wood for the frame, nor any mesh or clay for plaster.  Cindy and Kuba immediately began looking for a source of clay which would prove to be a long and difficult task.

Our first step was to have the carpenters install the sill plates.  These turned out to be 6×6 timbers that were nailed into the foundation with blocking every several feet.  The spaces between the sills were filled with coal slag, which it seems is commonly used as an insulating material in Siberia.  On Aug 21 we built the first post as an example for the carpenters, which they copied many times to creating all of the window and door bucks, as well as corner framing.  The top plate was to be flat 2x material layered with joints staggered at post locations.

Bale Stacking

By the 23rd of August the posts were installed and braced around the main gathering space.  We were pressed by our hosts to teach a “workshop” and educate everyone in bale-stacking.  Paul and I described how stacking bales worked and showed them how to re-tie a bale.  The bales were of marginal quality so treating them delicately was very important.  The eager participants soon took over and were stacking away.  Within an hour three walls were substantially complete and we made everyone stop due to the questionable weather approaching.  We needed to cover our work before it was soaked by rain.  The carpenters also needed to construct the top-plate assembly so the top bales could be installed.

All of the bales on the main room were installed by the 25th and we began using plastic lath, or mesh, to reinforce the joints between straw and wood.  Without a stapler, we attached the mesh to the wood with nails bent over and we had some of the students make pins out of wire for attaching the lath to the bales.  Much of this work was loose by the time we began plastering, but it was still good to have it held in-place with something.  By this time, no clay had been found despite a few forays by Kuba and Cindy into the neighboring countryside.  It seems that any people with a pit of clay did not want to share it.  We were in an ancient floodplain where the river had deposited silt and sand, but left little clay exposed that was available for use. It seemed very frustrating as loads of “clay” would show up that was not suitable as a plaster material.  Cindy was becoming frustrated and unable to find a solution.

By the 27th clay arrived as Cindy and Kuba had found a source.  It was good quality so Cindy had the volunteers begin applying a clay slip to the walls while others prepared cob to stuff into voids.  The work was fun and we could finally see the project happening.  Our hosts, however, had bigger plans.  We were asked our opinions about how far we could go during our three week visit.  We were scheduled to leave on the 31st which was less than a week away.  We strongly encourage our hosts to focus on the main structure and get a roof installed before attempting any more new walls.  They charmingly went ahead with their plan of having the lower walls framed, bales stacked and the shed roof framed.  At this point a group of twenty or so students showed up to work for a few days.  The results were nothing short of miraculous.  Where we thought they were flirting with disaster, they used all of the skills we taught them and managed to not only frame and stack the lower walls, but plaster them with two coats of plaster before we left.  We were amazed!

Having witnessed how slow things can go in Russia, we could not believe the motivation that was instilled by our hosts in their students and other volunteers.  Not only were they dealing with the workshop, but they had a budget that was running out and needed to be refunded by the Institute.  If they failed to meet certain deadlines the building would not be finished.  We watched Lena and Sergei expertly navigate a sea of regulators, engineers, administrators and volunteers, all the while smiling as we appraoched never missing an opportunity to treat us like family.  The experience was humbling to say the least.

Students and Volunteers

Mixing Plaster

As the clay slip was applied to the building, we asked about electrical wiring.  No electrician had been hired and we were getting ready to seal the walls.  I created an electrical plan with Lena and some students, some wire was produced along with boxes.  The boxes were nailed to posts and lathed in-place.  Wiring was run up the posts through the top plate where all wiring would be figured out later.  We decided on the location of the electrical panel so I could plan where runs would be made later.  It was another last-minute detail, but we were able to do what we needed before it was too late.

Most of the plaster was mixed by hand due to a malfunctioning mixer.  We limped the mixer along until it was completely dead and then had the students team up in groups to make plaster.  They were able to keep up well with the dozens of people applying it.  By the time we left, a slip coat and one coat of plaster had been applied to the entire building.  Plastic tarps were used to protect the tops of the walls and drape over the rafters of the lower roof.  We held our breaths praying for dry weather.  We had seen rain on and off most of our visit, but not in large quantities.  All we could do was hope for the good fortunes of our amazing friends to continue.

We received pictures of the final building just before Christmas.  The building has been completed!  They have lime-washed the earthen plaster and installed siding where needed.  The roof is on and the interior is finished.  There are two truth windows that are the largest we have ever seen.  They didn’t seem to be swayed by opinions such as “the plaster is a rigid part of this structure.  Leaving it off large expanses of wall may not be desirable,” or “If bugs and rodents do get inside your walls, it will be like a movie theater for visitors.”  The desire of these folks to push their limits gave us pause at times and we are impressed by their resolve in the face of possible disaster.

Clay Delivery

Lessons were learned about working with the locals even if it meant doing something in the wrong order or what seemed to be the wrong way to us.  They have their ways of doing things and even though we thought we could help them, there was great resistance to our ideas at times.  Stepping back and letting the owners of the project remain in control no matter what was happening seemed to give them a sense of determination that would not be derailed.  It turns out that they did not ignore or resist our ideas as we had thought.  They listened and integrated them into their program in the best way they could.  What became clear to me was that we were working with formally trained architects and students of the classical ways of architecture.  They paid attention to details and form.  On this project the function drove their form more than what seemed typical.

Finished Building

This building took all of the lessons they were taught about bale buildings and integrated them in a very functional way.  They used large overhangs.  There was not a single bale wall over 2 feet in height that was not protected by a wrap-around porch.  They used earthen plasters even in their extreme climate where temperatures reach -50 degrees (F).  They finished the plasters with a lime wash that will be easily maintained over time.  They installed two huge masonry fireplaces as thermal mass.  There is almost no solar gain due to the dense forest so they reduced glazing on all walls to what was necessary and functional.

Truth Window

We left Krona on August 30 after a quick award ceremony where everyone received some thank you certificate and a book on the design of straw bale houses – a first of it’s kind in Russia.  Our next stop was the old building that we helped build back in 2005.  That project was 6 hours south by car so we kicked back as best we could in the smallest car we could imagine and rested until we arrived in the heart of the Altai Republic and back in Chemal at The Milky Way.  We were interviewed by a video production group and welcomed generously by our previous hosts.  They had erected a handful of wood-framed cabins for guests and used the bale building as a tourist attraction and gathering space.  The plaster is holding up much better than we thought.  It is also earthen with a lime wash.

The 2005 Project near Chemal

On Sept 3 we were in Barnaul and boarding a plane back to Moscow and then onto Colorado.  It was another magical trip and one that was more successful than any of us thought possible.  The memories of bania (sauna) with friends every other night, meeting the families of our Siberian friends, working alongside our gracious hosts Lena and Sergei, and dancing around the campfire with all the volunteers who showed up for two weeks to help us and learn how to build with bales made for a deeply rich experience.  We look forward to seeing everyone again some day and to visit those two important projects that brought straw bale construction to the Altai region of Siberia.

We would like to thank the following organizations for their contributions and hard work:

The Altai Project
http://altaiproject.org

Trust for Mutual Understanding
http://www.tmuny.org

Builders Without Borders
http://builderswithoutborders.org

Institute of Architecture and Design in Barnaul

Fund for 21st Century Altai

Here is a detail of a window sill that we (Odisea) did on a project in 2000. Of course I can’t find any pics of a flagstone sill, but this one shows a slope of the sill and drip kerf. The CAD detail shows our flashing as a faint green line under the sill, which is extended beyond the plaster. The flashing was our “pan.” This project was done in my early days of really paying attention to the details, so there are subtle things I would do different, but the basics remain the same.

Window sill in Siberia

This second picture is a sill that we did in Siberia back in 2005. I built the window frames from scratch and then installed them into our window bucks. I placed a piece of thick building paper around the window and extended it out under the sill as you can kind of see in the shadow under the sill with the kerf. We were in the middle of nowhere and the people we were working for did not have any money so we used what was available.