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Mountains and Domes: A B&B in Thailand built using rice husks

By Asia, Design, Earth Buildings, Issue 70, Roofs No Comments

This article first appeared in The Owner Builder 192 December 2015/ January 2016. www.theownerbuilder.com.au

By Maggi McKerron

Ten years ago I fell in love with a mountain. Mt Chiang Dao rises 2173 metres out of the forests of northern Thailand, its jungle covered peaks dressed in swirls of clouds. I leased a piece of land on a small hill facing the mountain. Under half a hectare, the land slopes down to a small rural Thai village under the mountain, clustered around the nationally famous Chiang Dao Cave.

Planning a B&B

I was approaching upper middle age and realised I needed to make some sort of plan for older age when my life might possibly slow down a little. This piece of land would be perfect for a B&B!

I did not have the money to develop the land, so I took off for the UK to make some. Although I am British, I was born in India and have always lived in Asia. Going to the UK to work was a challenging experience, as I had to learn to live in a western culture for the first time, at the age of 56.

mckerron-_24

Earthbag B&B

While in the UK I took the opportunity to study natural building, beginning with an inspirational earthbag building workshop taught by Paulina Wojciechowska, author of the first book on earthbag building. Making a dome out of earthbags sold me on domes and round dwellings. I was determined to build round domes back in Thailand!

Rice husks

But using earth as the building material did not sit right with me. I am mildly asthmatic and need dry air and did not relish the thought of being enclosed in an earthen dome during six months of monsoon rains. I thought about rice husks. This is a product that no one wants. It takes ages to break down if added to compost, and is difficult to burn. It is also a desiccant, which means that it will draw moisture out of the atmosphere. Perfect!

After seven years in the UK I finally had enough money to return to Thailand. At least I hoped it was enough. There was no way I could calculate the costs of the buildings in any detail, as I did not really know how I was going to build my rice husk domes. I couldn’t find any information on the internet: no plans available, no books on building with rice husks. I worked out a financial guesstimate, which I finally reached in savings, and I bought a one way ticket back to Thailand.

My beautiful land was covered in towering brush and it was not until a team of machete wielding villagers cleared it that I discovered how steeply it sloped. What a challenge this was going to be!

I should mention here that where I was building, out in the scarcely populated countryside, planning permission, although preferred by the local council, was not an issue. In towns and cities I would have had to submit plans. My local council signed off the building after it was finished.

Beginning the build

Ready to begin my adventure, I posted on social media that I would welcome anyone who would like to help with the project, and people turned up. I hired some local day labourers from the village. We found the flattest area, at the top of the property, and one of the first steps was to prepare for a concrete base. I had been warned by locals that the termites were ferocious and there really was no alternative to concrete.

We marked out a circle 5.5 metres in diameter with some bamboo stakes. Then we got some tubing and filled it with water, and tried to find a level. No one believed what the water in the tubes was telling us, so I went and bought a spirit level. This confirmed the water’s message; there was still a big slope, even though compared with the rest of the land it looked practically flat. Leveling the area was our first task.

My very rough plan showed a concrete cap on the dome, as this was all I could think of to keep out the monsoon rain, so our next task was putting up six concrete posts to carry the weight of the concrete cap. Then the base of sub soil and stones went in, pounded flat
by enthusiastic volunteers, a trellis of bamboo for strengthening, a sheet of plastic as a damp proof membrane to stop moisture leaching upward, some sand and a final topping of concrete.

The dome

Now I needed to seriously consider the dome. I could not for the life of me work out how to construct it. Unlike earthbags, which are load bearing and could support a concrete cap, I was working with lightweight, not at all solid, bags of rice husks. I spent ages in hardware stores, second-hand wood shops and looking through books. I asked various local builders, but one after the other they shook their heads, mystified with the ideas of the crazy foreign lady.

At one point I decided to forget the dome and just build a hexagonal roof using the steel for conventional roof frames. One of the volunteers said: ‘But Maggi, your dream is a dome. You must follow your dream.’ So I thought again.

Weaving the bamboo

Weaving the bamboo

Bird cage

I found reinforced steel rods, rebar, bendable and long. I could buy quite thick pieces and long enough to go from one side of a dome to the other. First a piece of rebar was bent into a circle to go around the building, sitting on the top of the concrete posts. Then up went the rebar making the dome shape and we wired it onto the posts and horizontal rebar. Using different thicknesses of rebar and adding bamboo we made a dome shaped trellis.

The bamboo for the trellis in the dome came from bamboo poles we harvested from the land. These we cut and prepared and wove as needed. We used the same trellis idea for the walls, and our bags of rice husks would be attached to this frame. The whole thing looked like a giant bird cage!

The windows and doors were added as we built the bamboo trellis. This was complicated as the walls were going to be quite thick, so windows and doors needed frames to sit in. We learned as we went along. At no point in the building did we use any electrical tools – there was no electricity!

Rice husk walls

Filling in the walls came next. I found a place that sold second-hand polypropylene bags and had bought several hundred. Then I found a rice mill that agreed to fill the bags for me with their waste husks, 200 a week. These we had been collecting in preparation.

The first layer of bags was filled with gravel to guard against water and moisture damaging the walls, with a layer of sand on top of that, then the bags filled with rice husks. We experimented with different types of string, and different knots and found the method that worked best. They went up quickly and easily in a couple of days, and soon we were at the level where the curve of the dome began.

The bags were too big. They would be too unwieldy and heavy to attach. We had to empty them, refill them with less rice husks, then tie them up in the shape of a sausage. Our sausages were quite complicated to put up as we were attaching them to the inside of the dome to continue the inside line of the walls.

The dome looked wonderful! The next step was to put on the concrete cap. We used plastic sheet covered with chicken wire and put the concrete on top. We made deep overhangs to protect the walls.

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Finished dome

Mud render

The last step was the mud on the walls. It took a while to perfect our recipe as putting plaster on bags of rice husks is not the same as putting it onto earthbags or straw bales. The bags were not solid, so plaster had to be built up slowly in several layers until it was firm and strong. Then a final layer of lime plaster, followed by some decorations, and our dome was finished!

The big lesson I learned was never to put a concrete cap on a dome in the kind of climate found in Thailand. It cracked, and cracked again! But because the rice husks dry out so easily it has not caused any lasting problems. The second lesson was to attach the bags to the outside of the dome trellis. Much easier!

Three years have gone by since the beginning of the adventure. I have three domes and five roundhouses with thatched roofs. All the buildings with their thick walls of rice husks covered with earthen plaster are cool in summer and warm in winter. I have a beautiful home, made from three of the five metre roundhouses, joined by thatched walkways. My B&B is up and running. And every day and all day I can see my mountain. My dream has come true.

Maggi will be running a roundhouse building workshop in November 2017.  See website for details: www.chiangdao-roundhouses.com

Links & resources

Maggie’s Blog

Sharing her adventures of living – and building – in Chiang Dao, northern Thailand.

maggimck.wordpress.com

Chiang Dao Roundhouses

Set on the side of a hill overlooking the spectacular Mt Chiang Dao, offering rice husk workshops and B&B accommodation.

www.chiangdao-roundhouses.com

A Straw-bale Home in Idaho – TLS #55

By Bales, Design, Plaster, Roofs, Straw Bale Construction, Walls One Comment

This article originally appeared in TLS #55 and was the feature article in that issue.

house1by 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

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

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.

diningWhen 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.

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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

Why We Build with Earthbags – TLS #55

By Roofs, Walls 4 Comments

This article originally appeared in TLS #55.  This article is one of several natural building materials covered in the issue. There are earthbag articles in these other issues: #52 An Earthbag/Papercrete House; #28 Earthbag Construction; #16 Earth Shoes: Earthbags (used as foundation); #57 Earthbag Structures in Disaster and Poverty-stricken Areas.  Subscribe to TLS to enjoy more articles like this or purchase back-issues at The Last Straw website.

by Kaki Hunter and Doni Kiffmeyer – Utah, USA

earthbag1We 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 Home

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.

earthbag3-240x300The 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.

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.