(Czech language version printed in 'Klickova Dirka' 03/09)
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‘Pig Oven’, Bouzov Svojanov 2002 |
As a Natural Builder I’m often confronted with the popular conception that I’m simply a happy amateur playing as a pig in mud, and building something like ‘semianka’; the simple underground shelters made in Russia, and afraid of using machinery etc.
While I’ve more or less given up trying to change the opinion of such view, then the truth is somewhat different; Fact is that for the past 10 years I’ve attended numerous scientific international ‘Lehm’ conferences in Germany, (as well as the more regional conferences in Brno and Bratislava), studied at the Adobe Construction College in El Rito, New Mexico, learned about cob at the Cob Cottage Company in Oregon, Earthships in New Mexico, CEB’s when I worked for Oskam (producer of machines for Compressed Earth Blocks), and hosted and attended numerous courses with some of the most experienced earth plasterers in Europe; not bad for a happy amateur! (And the list does not include how I've learned about non-earthen materials; straw, papercrete, wood, etc.)
The above experiences has taught me that earth is one of the most versatile and healthy building materials we know of, in edition to the fact that it’s plentiful, local, renewable and inexpensive. But what is actually Earth? Or rather what is it we use for building?
In common language we talk about earth consisting of sand, clay and silt. However when we’re judging earth for its building qualities we look at a series of essential properties, which Prof. Gernot Minke describes as follows: Degree of dry shrinkage, binding strength (adhesion of the clay plaster), abrasion resistance, compression strength, tensile strength, edge fastness and absorption capacity (moisture uptake). There’s also the color property, in case you’re considering to paint or plaster with it.
These properties are all influenced by a variety of qualities such as what kind of clay molecules it is, amount and kind of sand, size of sand molecules, even the water quality; There’s big difference if you apply basic or acid water to your mix!
In addition to this there’s the element of fibre you add to the mix, which basically means that you can change the earth from suitable to paint on a wall, to fine 2-3mm plaster, or to the extreme of making hard pressed building blocks or cob (a mix with about 60-70% straw for building walls by hand).
The good part about this ‘science’ is that the best way to learn is ‘Just Do It’! Nothing beats digging up your local soil, mixing it with water and chopped or whole straw and simply trying out a small project, weather it’s plastering a small wall or building an earthen oven. You’ll likely feel the healing effect of the earth on your body, or simply experience that now you’re allowed to do what your parents told you not to do because you’d get dirty!
Once you have gotten that far you may want to read various books about earth building. Our ‘bible’ is called ‘The Hand-sculptured House’ By the Cob Cottage Company. It will teach you almost all what you need to know to situate, design and build a lovely home. If you are of a more scientific nature you should read the books by Prof. Gernot Minke as well. At this stage it would be beneficial for you to come to some courses; I’d naturally recommend the ones we arrange at our Centre for Natural Building, as they are very hands-on and together with an American experienced educator and Natural Builder, we offer internships and special courses in 2010, however there’s several others offered during the season.
I recently took part in a course at the European School for Earth Building in Germany titled “Clay Plaster, Module 2: Pedagogical Methodology in Sustainable Natural Building”.
The course is rather expensive, and aimed at educators, however it is of high quality. We learned a series of different tests, perhaps with the simplest being the most eye-opening; take a kilo of earth from 2 different sites, perhaps some km’s apart. Now, try to make 5-7 small piles of each of the types of earth of exactly 200 grams, and first add 20 ml to one pile, 40 ml to the next, 60 ml and so on, while you’re trying to make the pile stick together and create as tall a ‘tower’ as you can make stand on the table.
Such simple comparative test easily demonstrates the diversity of the clay minerals, and you’ll be able to judge which soil to use for your next job: Did it crack? Does it bind well and so on.
The course covered a long list of techniques, and I especially enjoyed learning the Sgraffiti technique; You plaster an area with several layers of different colored plaster, and by scraping at various depths, with various tools, you gradually create your art work, as you can see on the index page of www.permalot.org.
I hope you also feel inspired to take the step and ‘Do It In Mud’!
Ing. Planning and the Environment.
