I made a comment on Facebook recently stating how much I love to work with cob more than any other earth building method.
Here’s a selection of techniques and my impressions which help me decide which method to use in a specific location:
We’ve built Earthbag foundations in Canada (OUR Ecovillage ), Tanzania and Cameroon. The earthbag foundations work well and are low cost in places where stone isn’t available.
At a Natural building colloquium I filled long tubes with earth. Friends from the natural building movement have built beautiful domes and other homes with this method. I believe if there’s clay in your soil, forget the bags and build freely with that clay-soil. It’s a matter of location and what’s available.
Another amazing technique producing beautiful and stunning buildings is Rammed Earth. Layers of different colors tell the story of the earth at the location. I’m talking about rammed earth free of cement here, as its being done by several builders in Europe. This way of building requires serious formwork and planning. My personal experience is limited to observation, because in my work I’ve been in locations where that formwork is very difficult (expensive) to build. As a result rammed earth shows up on the high end of building cost and in larger scale buildings.
Many cultures have built with Mud blocks (Adobe) and still do so. Here in Cameroon I see homes being constructed with a mud-block infill system, using concrete for structural support: ringbeams and to bridge large openings. Local people have experience producing these blocks and will make their own when it’s time to build a home. Making blocks doesn’t require much: water and clay-soil. Fiber isn’t so commonly used but is useful to prevent cracks and to strengthen the blocks. You need a flat area to lay out the blocks to dry in the sun- this will take about a week. Then dry storage until construction begins. Building walls with blocks requires some skill- to build a house takes some practice at masonry work. And those blocks are very heavy to lift. However, depending on seasonal patterns and workflow, this can be a great way to build an earth home.
Compressed Earth Blocks
Compressed earth blocks (CEB’s) can be made with or without cement for stabilization in various shapes and sizes. Simple mechanical block presses require at least two people to work together – mixing the clay-soil (sometimes sifted) with a little water, then filling the form and compressing with the power of a long lever. Scale it up and you’ll see machines working with hydraulics taking the hard work out, but driving up the cost . The result is a firm, even block, sometimes interlocking. We’ve just finished building our dormitory walls with CEB’s – because we had the perfect soil on site, were too late in the season for sundried blocks , and had straight walls to build. We hired a local builder to lay the blocks as they came from the press. It got the job done.
Parallel to this process our volunteers were building with cob. We created some hybrid walls with the blocks to add sculptural details and bottles. And we shaped benches and a lounge area. A layer of cob fills awkward spots in the block walls (filling around posts etc) . I watched inexperienced building volunteers mix great batches of cob, build the walls and trim them. Everybody took on designing with bottles- allowing one individual to be the overall artistic eye.
And that’s where that statement came from.
Watching people, who have never built anything, confidently building something beautiful makes my heart sing.
We’ll be moving into Earth plasters next – where sculptures get refined and block-walls disappear behind a hand-applied layer of mud. Earthen plasters can be simple sand/clay mixes applied by hand or more sophisticated ones with additions of ingredients like mica or marble dust, finished with special trowels. It’s up to the availability of materials, skills and taste, desires and budget of the owner.
Hybrid of techniques
The beauty with all of the options above is the possibility of mixing things up. We call it hybrid homes- for example walls of cob on one side and straw-bale on the other. Or adobe with inserts of cob for bottles and other sculpted elements. All tied together with beautiful natural plaster finishes.
I’m heading to Kenya this summer to create a cabin for my host Joannah in a couple of workshops. She’s already collecting beautiful things to incorporate. Dreaming her space. Clearing the site.
When participants arrive we’ll work with a selection of techniques appropriate to the location and learn about decision-making in the process. This opens up the possibility of being creative builders in collaboration with others. We’ll be supporting the first stage of a learning center for permaculture in a protected forest.
So if you are so inclined, come to Kenya this August! You will get your hands muddy and experience a different sort of safari!
Did you know that countless women in Africa cook the family meals on 3-stone fires? I don’t have statistics, but I see the evidence all around us both in the city of Bamenda and when we go to the Village. I have mentioned building improved wood stoves frequently since our arrival here, and many women say “I want one”, but it took initiative and some funding (VSO thank you) to actually start building.
It’s a project!
Wopong Jocelyn Achu asked me to come and teach 15 women in the small community of Pinyin in Santa, to the South of Bamenda. She is working as VSO (Voluntary Service Overseas) national volunteer for HEDECS (Health Education Development Consultancy Services).
We set the goal to build one stove with the women in a workshop, perhaps start a second one and then leave supplies for them to build another five stoves by the end of the month of January. We hope that this will trigger further stoves to be done under people’s own initiative.
Some research into the topic in combination with my own experience from previous stove projects produced a handout with mostly visual instructions. I know what it feels like to learn something in a workshop and try to do it alone the next time: a guideline is helpful, and since not all women read or speak English, it had to be visual.
To make things affordable and easy to repeat I looked for simple, local solutions for elements like form work, chimney building, tools and materials.
We left Bamenda in the early morning by shared taxi to Santa, from where we carried on by motorcycle to Pinyin. Mountainous terrain with densely farmed valleys, this is a highly productive region for vegetables that are distributed throughout Cameroon and beyond.
The women gathered in front of Lillian’s house, where we would be building the stove under a good sheltering roof next to the front door. But not just women wanted to learn, a group of secondary school girls attended as well and many men and youth came by during the course of the day.
The list of materials :
Claysoil ( the pit was in the yard)
Two sacks of sawdust
Small quantity of sand (most precious there because it is brought in)
Tools to have at hand:
Tropical hoe to dig and mix clay
Measuring tape (if unavailable use body measurements)
- Take the largest pot that will be used on the stove and determine its volume
- The volume relates to the size of combustion chamber and heat path through the stove (all the same cm2), a simple chart is available to look this up: download publication
- The width of the stove will be determined by the diameter of the pot plus insulation plus bricks
- The length of it is the sum of the first pot plus a second, smaller pot, plus chimney plus edges and channels.
- Finally the height of the stove as illustrated in the sketch
Building the stove:
- Prepare a 1:1 (by volume) mix of clay and sawdust (estimated 4 wheelbarrows of clay) and a clay mortar mix
- Layout on the ground: position pots, mark center lines and edges on the wall
- Set edges with bricks and configure firewood feed and combustion chamber (considering 5cm insulation)
- Build up edges and combustion chamber.
- Insulate combustion chamber. We used banana stems as guides which I saw in my research, but decided to pull them up as we built up instead of leaving them to rot in place, as suggested)
- Fill voids with compacted earth or bricks
- At appropriate height set the first (larger) pot in place and fill around it with insulation mix.
- At the same height the channel to Pot 2 will be built with insulation mix, followed by pot 2 set into place
- Continue building up around the pots to desired height.
10. Make a channel to the chimney and set up a form to build the pipe (banana stem works here too)
11. Remove the pots and smooth all edges and surfaces inside, scraping down the surface around the pots to create hot air circulation. Place three clay supports to lift the pot- allowing heat to move under and around the pot.
With the experience the women had – they already know how to mix mud, make bricks and lay bricks- we accomplished the first stove in about 4 1/2 hours- with much deliberation and figuring out the process.
To my great surprise everyone got up after the meal that followed, and carried bricks to the next house. And then the women went ahead and within 1 ½ hours built another stove with little input on my part!
We will return to Pinyin to do some surface finishing and to see how things are. And we hope to light the fire in the first stove at that time. When all is done and our feedback is in, I will publish a full report and make it available for download.
At time of publishing this post, the women have built three more stoves and are on track for the last 2. I am now working with another group of women on constructing a cabin, an oven and a stove….stay tuned!
Get your hands into some good African Earth!
Inviting Natural builders to come and help build our first buildings at Ndanifor Permaculture Ecovillage , Bafut, Cameroon.
It’s time to build something this dry season: we have plenty of good building earth, raffia and access to wood.
Come and help create a small cabin as a first place to stay on the beautiful rural site. We have called out to women groups and local youth to participate in community training programs from January until March 2014.
Part of the activities will be the building of a wood-cook-stove and bread oven for the ecovillage learning center.
Work with me to support this community effort and give Better World Cameroon its first real natural building experience. Share what you know and get practice by immersing yourself in a different context. And escape the northern Winter.
You can also find the project on thePOOSH and follow updates there.
Lets’ talk logistics:
- You’ll need a Visa to enter Cameroon– this is usually not difficult, but it poses a time factor. So get on it quickly. We will provide a letter of accommodation or invitation as required for the Visa. Check with your closest Cameroon Embassy.
- You’ll fly into Yaounde or Douala- both are about 6 hours distance from Bamenda by bus. Buses leave mornings or evenings and cost about $10. It’s easier for us to arrange for someone to meet you in Yaounde- Better World has an office there.
- Living in Bamenda is fairly low cost- Better World will help find a suitable place to stay and negotiate a price for you.
- Good food is readily available at low cost. We will share some common meals and spend free time exploring the hills in the area. Our plan is to work on construction for 4 days a week starting January 13. You can join any time until March- we hope to be finished by April 1.
- Better World has a FAQ page that may be helpful.
Can we complete this building in 12 weeks?
If you have time and a travel budget consider our offer. Get your hands into African Earth!
Please email me to discuss details and if this is not for you, share it with someone!
Today I saw this call for support and want to help spread the word.
In 2009 I had the great pleasure to go to Hopiland in Arizona and work with Lillian Hill and Hopi Tutskwa Permaculture to start the construction of a house for Lilian’s Mother Serena. I was touched by the community spirit and the strength of the cultural roots that we experienced there.
Please consider supporting her and her community.
Interesting linksHere are some interesting links for you! Enjoy your stay :)
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