Read reviews of the first three books in the Sustainable Essential Building Series by New Society Publishers – Hempcrete Construction, Building Science and Prefab Straw Bale Construction.
This article first appeared in The Owner Builder 196 August/September 2016. www.theownerbuilder.com.au
By Hannah Moloney
As we live on a steep slope we’ve had to build a lot of retaining walls in order to create functionality around access, water management and food production. We’ve used a range of techniques to do this including working with old car tires to build a big earthship-style retaining wall near our house.
Earthship construction is a building technique developed by American architect Mike Reynolds. He’s famous for using ‘rubbish’ and earth as building materials. We love his work. We chose to build an earthship-style wall as we had a small budget and a lot of excess subsoil left over from our initial earth works. We also knew we could get car tires for free from the local car yard who have to pay to get rid of them.
Check your soil
We hadn’t built one of these before, so we spent some time on YouTube learning how – there are plenty videos to watch. While it’s pretty easy, it’s also a lot of hard work. It would have been whole lot easier if we had heaps of people to help, one of those cool Wacker Packer tools and dry, gravelly soil instead of the wet and sticky clay subsoil we’ve got at our place.
This last tip is really important: the YouTube video we watched made it look like a walk in the park with dry, sandy soil in New Mexico. The builder just poured it into the tire and patted it down; in contrast we shoveled, packed, wacked and shoveled some more. It was a bit of a mission. But it’s an incredibly strong wall and used up much of our excess subsoil, for which we were grateful.
Plug, pat and pound
Starting out, we cleared the space, tacked some white geofabric to the bank to keep it from dropping crumbs and made a level pad to start laying tires. As we were almost on bedrock, we didn’t have to lay any sand or concrete for footings; we just leveled it off.
As soon as you start building up from your first tire, you have to find a way to plug the holes so the earth doesn’t just fall through. We had a pile of carpet tiles the previous owner had left under our house, which fitted perfectly, so we used them. We backfilled the area directly behind the tires with 20mm blue metal and agricultural pipe to guide excess water out of this area. In addition, drainage holes are also necessary, as you never want any water building up behind a retaining wall.
We went five tires high and angled them all slightly towards the back for structural integrity. An important thing to note is that if you go over one meter high for a retaining wall you need an engineer (in our region at least) to design and approve things, which can get complicated and expensive. Because of this, we didn’t exceed this limit – it might look taller below, but that’s because the earth around the wall had been excavated and the paving hadn’t been put down yet.
Plug the gaps
The next step involved plugging the holes between tires with subsoil. The best approach was to simply form balls of sticky soil, ‘peg it’ (throw it really hard) into the gaps and then pat it in to make sure it’s all bedded down. After that, we wrapped the whole wall in chicken wire. This is what the external renders ‘hang on’ and it helps create a smooth, level surface.
We chose concrete render instead of earth for two reasons: firstly, this wall is in the coldest, dampest area of the whole property so it needs to be able to handle long months of never seeing the sun and being constantly wet. Secondly, we’re not overly experienced with earth building, so we took the conservative approach.
The finishing touches
Recently we (as in, Anton) did the paving around this area using recycled bricks that were pulled up from our local town square. This was the final job to do before we painted the wall bright blue with a colorful patterned border.
Another nifty feature of our new wall is little steps leading up to our food gardens. The only downside to these steps is that our little daughter Frida Maria loves climbing them. When you’re not looking she’ll be up there in two seconds! We’re happy she has a great time there, but it’s just that the potential of falling onto the hard bricks below is a little too stressful for us. A little gate may be in order.
We’d love to see more people using recycled materials to build inside and outside their homes. The amount of ‘rubbish’ in our world is mind-boggling and when we look closer at so-called rubbish, you’ll notice that most of it could actually be re-purposed into a valuable resource. The possibilities are endless – we just have to pull our socks up and get creative!
*Just a quick note: car tires can have some leaching of chemicals, which we wouldn’t personally be comfortable putting near food gardens. So this wall isn’t near our growing beds. Everything downhill from it (the leaching will move with gravity) is all brick paving and house.
Hannah Moloney is the co-founder of Good Life Permaculture offering design and teaching centered around the concept of radical homemaking, placing home and community at the core in order to create a good life. www.goodlifepermaculture.com.au
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.
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!
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.
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.
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.
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
Sharing her adventures of living – and building – in Chiang Dao, northern Thailand.
Chiang Dao Roundhouses
Set on the side of a hill overlooking the spectacular Mt Chiang Dao, offering rice husk workshops and B&B accommodation.
This article first appeared in The Owner Builder 196 August/September 2016. www.theownerbuilder.com.au
By Brian Hodge
As we embark on our 20th owner-built home, I reflect back over the progress since purchasing property last year.
We were surprised the property didn’t have power, sewer, or water but discovered it actually had sewer connection just over the back fence. We were somewhat pleased when we received the quote for electricity connection of $5,050. Mind you, that did not include the connection of the power to our meter box.
Having mentioned the meter box, I am flooded with the memory of its incorrect positioning in my unavoidable absence and the challenges that we were faced with as a consequence (see TOB 195 June/July 2016). But who can complain. The end result was that we have revisited the design and now have a better one that is more interesting. And who can forget the bonus sewer connection at the back of the block, which will save us around $10,000 that we would have spent for a septic system.
A place to run courses
When we first went looking for land our primary motivation was to get a low cost piece of land on which we could run the practical part of our owner-builder straw bale building workshops. This was a precursor to being willing to sell the straw bale house in Ladys Pass. To be a straw bale building consultant with nowhere to do courses and nothing to show people was not an option and the solution had to make financial sense.
Consequently, I did an internet search for ‘land under $50,000 Victoria.’ The result was land in Loch Sport, which was too small and, from previous experience, has too many mosquitoes, and land in Inglewood, Victoria. Inglewood is in central Victoria about 35 minutes north of Bendigo with a population of a bit over 1,000. It was established in 1859 and is still a great place to find gold. It has a good supermarket, hospital, permanent doctor, pharmacy and most important, a couple of good old fashioned pubs for great meals. It is also the town where my youngest son, his wife and two of my grandchildren are located. However, the criteria were primarily price and size.
There was an 8000m2 block for around $45,000 near a light industrial area, a 2000m2 for $70,000 or a 1000m2 for $35,000. We put in an offer of $33,000 on the last block, which was accepted.
The only issue, which was a big one, was its orientation. It is only 20 metres wide and faces north-west. In order to control heat input and get some passive solar benefit in the design, we had to design a house that is twisted on the property. This option consumes a lot of land, which was complicated by our need for wide eaves for a straw bale house. Regulations stipulate that living area windows must have a minimum of 1000mm of clear sky from the boundary, which meant that we had to be set in from the side boundary a minimum of 1900mm to allow for the 900mm eaves. We also needed truck access to the backyard to take deliveries of bales etc. for workshops, further restricting our build space.
We finally settled on the concept of building a U shaped house with a central courtyard as this would enable us to get passive solar benefit in the master bedroom and living area. Not a huge amount, but enough to make a difference. It also provided us with a outdoor private area, which is important to us as we have lived on country properties for the past 12 years.
I had our energy assessors check to see what difference this adjusted orientation would make on stage one of the construction, as opposed to building parallel to the front boundary. We were surprised that the energy rating actually went up from 5.4 stars to 6.3 stars even though there is only one window that faces north.
As we are building in central Victoria, the energy rating is primarily directed toward the energy required for winter heating. However, we get some really nasty weather in summer with temperatures reaching high 30s and even mid 40s. Consequently the design criteria also included resistance to summer heat. The central courtyard faces due west, however it has a deep verandah to protect smallish windows from the afternoon heat from the west, and the windows facing east are limited.
One of the big concerns for restricting heat input in summer is to avoid doors that open directly into the house from the north, as it is the north wind that brings high temperatures to the area. I have therefore included a good size entry on the northern end of the house with the external door facing east, which will dramatically reduce the impact of those hot northerly winds.
The cooler summer breezes often come from the south-east, so we have included casement windows on the south-eastern boundary to funnel those cool breezes through the house. The benefit of correctly hinged casement windows is that they tend to trap the breeze and funnel it into the house rather than simply working with straight airflow. When you are trying to get cool air into your home it is best to open the windward windows fully but close the windows on the opposite side of the house to 50%, as this creates a vacuum resulting in greater airflow.
As this is a residential block I expect that airflow will be a bit of a challenge as we have boundary fences which will restrict it. I have also incorporated a flat ceiling in part of the house in order to accommodate ducting for an air circulation pump to force the early morning cool air through the house if the temperature in the house is higher than the temperature outside. Our previous straw bale house in Ladys Pass had the same issue, which was overcome using an evaporative cooler as an air circulation pump. The cooling function of the unit was hardly ever used, and would not have been missed, so I am planning on simply fitting an air pump this time.
The master bedroom window faces north onto the central courtyard, however the window is not within the shadow of the verandah roof so we will get good passive solar benefit in winter. It also means that we have a private outlook, and with Molly, our big guard dog, we are assured of security! (Molly is a miniature Maltese Shiatsu)
As this is house number 20 for us personally, it was difficult to find something a bit different to do, so we eventually settled on a curved roof with a curved ceiling. This will be achieved by building box trusses on site. It is a very cost effective method of roof construction and I am looking forward to trying it out, as I have never done it before.
With all the design, engineering and building permit issues behind us it is now time to get to work and build it. I am going to take my time and enjoy the process as I suspect this will be the last home that I build, although many people scoff at this idea, thinking that I am either crazy for building so many or that I am addicted to the process. Personally I am not sure, but I am going to enjoy this project as if it is my last.
Brian Hodge is the director of Anvill Straw Bale Building Consultants. He has nearly 40 years experience in the building trade, and now consults predominantly on straw bale construction. Brian is the author of ‘Building your straw bale home’ and will be blogging about his build. Anvill Straw Bale Building Consultants: Whether you are building a mansion or to a strict budget, we are here to help. www.straw-bale-houses.com