Integrating a channel for fresh air intake in the cob wall

I expect the shelter to become very air-tight. Or at least the ambition is to get it as tight as possible for good temperature control. The only really critical part, where cold air might blow in uncontrolled is the door. But if I buy a ready manufactured door, it should become really tight.

However, it would be desirable to have the possibility to open for some controlled fresh air intake, in particular when the rocket stove is running.

Therefore, I have now integrated an air-intake channel in the cob wall. The channel should give me the possibility to open for some controlled air flow into the shelter. The direction of flow should simply be driven by the draft of the rocket stove.

I got 3 minor pieces of a flexible plastic pipe in a useful diameter from a dump container. I just had to piece them together using a few cable ties.

I have placed the channel with the intake to the west facade to take the air directly under the roof overhang. The tube then runs along the wall, but strictly downwards to release the air about 15 cm above the floor at the northern wall inside. If condensation water would develop, it would run downwards into the shelter and could here be collected in a little container. However, in winter time, the air in the tube would most likely warm up on the way through the intake channel in the cob wall. And therefore I do not really expect much condensation to occur.

At first I hesitated a bit to place the pipe along the wall. I was afraid this may compromise the walls stability. But after having ‘cobbed‘ the pipe in, I feel that the pipe may even improve the strength, because of the direction of the reinforcement by the straw, which – I imagine – after pushing the straw with the rod, will be placed needly and snuggly in the corrugated outer structure of the pipe.


After day 1.

And after day 2.


Last not least, the status quo



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cob shelter, plan and update

I had to apply for permission to raise the shelter in my garden. Because the garden colony area is under nature protection, the regulations are rather strict.


I got a friend who is good at google sketchup to draw a quick sketch.


The south front is all in glass and is directly extended with a greenhouse of 5 m2. The cob construction is thus limited to three walls, west, north and east. The dimensions of the sketch are not quite right, but it still illustrates the idea.

The roof construction will be from wooden logs, used floorboards and topped with a layer of soil.

Last winter and in preparation for the construction I fell a few Nordmann firs in a nearby, old-grown christmas-tree plantation. Of course with permission of the owner.


That was quite challenging as there is hardly any spot in the densely grown forest to let the trees down. And I promised the owner of the forest to not create any clearings, but rather to pick a single tree and then move further to another area. So all trees had to be taken out from another densely grown area. Consequently, the only way to get them down was to clime the trees with a saw and cut all branches and the top before falling the remaining trunk with the power saw. This is probably not the way to pay one s last respect to a tree. But at least I tried to do it quickly.

The axe was used to strip the bark, which was best and easiest done within a few weeks after falling. Preferably immediately.

I left the trunks in the forest, where they are still laying – off the ground – in the dark forest and protected from direct sunlight not to develop cracks.

I just brought a single one home to the garden, because I had to find out if I could do it with the sack barrow as I envisioned.


And yes it worked. By now they are much dryer and lighter.

The west wall is taking shape. With a critical look at the cob work you can still see the different layers of different working periods. When I work day by day, I can on the second – and even the third – day still work the cob from the first day by pushing the rod from the side to punch holes. When I take breaks, the cob dries so much, that it is impossible to form it any longer.

You can see from the form of the wall and the color nuance the result of 4 times 3 days of work. The tiny part of the wall to the very left is by now completely dry and as hard as concrete.


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Improving the techniques (cob)

One of the big advantages with building in cob as compared to other methods is the extreme flexibility. It is almost impossible to mess up. There is always a possibility to correct afterwards. For example, when the wall becomes to thick at some point, you can simply saw the excess down again. You do not even loose your material, because you can soften it with some water or simply add it to the next portion you mix.

However, there is a good reason to develop some routine and to work in a more organized fashion not to do futile work. It is nice that you do not loose you cob material when you take parts down again. But anyway, pounding the mix, forming the balls and working them onto the wall is hard work. You do not want to do this over and over again.

I have developed some routine by now. The first routine concerns mixing and forming the portions. All in order to build a straight wall from the start.

In the beginning I formed the portions as balls. But it turned out to be a lot of extra work for the hands. And it is not easy to get even portions. They turned out to be very different in size. Now I form them as flat discs, also called breads.

It reminds a bit of a bakery, does’nt it? Biscuits left and breads to the right.


And here is how I make them.


Once the mixture is homogenous and the proper amount of straw is added, I collect everything one final time in the center of the tarp.


And now I pound it one final time and as evenly as possible like a flat pancake.


Then I loosen it by pulling the tarp over one time and only in one direction. Now it becomes very easy to pick portions of equal size. I just need to close to edges of the portions to form some bread-like shapes.


Ready. Now its time for a break.


Home made rye bread with ramson pesto.

The other part of the process that deserves some degree of organization is the work on the wall itself. Instead of pushing the rod higgledy piggledy from all sides into the newly places bread, it is advisable to first tag it by firmly and deeply pushing the rod in all directions through the layer of cob underneath.

So far so good. I stopped counting the days. The only thing I know is that I need a day off. 8)


And above all, I do not know how many holes I pushed in the growing wall. Must be in the 10th of thousands by now as judged by the wear out seen on my first pushing rod, which needs a replacement.


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I am building a cob shelter

I have started building a cob shelter in my garden on the country side. The structure is going to be 10 m2 and combines to the south side with a 5 m2 glasshouse. The floor level of the shelter will be about 40 cm below ground. This is just where the top soil layer turns into sand. This will give me a better foundation.


I started by laying down a row of 50 x 50 cm floor tiles as the bottom of the foundation. The tiles do though not provide a capillary insulation from below. Therefore I needed to place some big stones, natural rock, on top of the tiles in order to build my cob wall separated from the capillary forces from below.


It is a bit of a puzzle to place the stones on the flat tiles. Obviously, for a good foundation they need to get into a firm position. It is a matter of try and error.

But in the end I succeeded. Now I can walk over the stones without them moving. The rock foundation is now up to 50 cm broad, enough to build a 30 cm thick cob wall.

Finally I can start building in cob.


After a number of tests I decided to mix 2 parts of my clay rich soil fraction with 3 parts of sand. The amount of water needed to reach the proper consistency is very tricky, and has to be adjusted on the daily bases. Depending on wheather and rain fall.

After mixing by pounding the mass with bare feet on a tarp, I add straw to the mix. Not too much at a time. But the goal is to include as much straw as possible. Straw has many functions to the construction. It increases the tensile strength of the wall. But it also serves as an insulation.


Finally, I take portions of the cob to form to balls ready as building blocks.


30 cm thick, 40 cm high and about 3 m long is the result of 6 days of work. Not too bad for a start.

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Capitalism is a culture of waste

There is two ways to define waste. One is, that an item turns obsolete and cannot be used any longer. The other is that the item is toxic and therefore of concern for the environment.

Ironically, both problems are man-made.

Now it is time to address both of them.

Poor people, in particular in poor countries, generally do not trash things because they always find a use for everything. Things don’t turn worthless, just because they no longer serve the original purpurse. Everything can always be used for something. After all, it exists. Why burning or burrowing it?

Not because poor people were concerned about the waste as toxic waste. Initially not. Now, they are – for good reason-, as trash from industrial production is shipped to and disposed on their land. But in the first place, poor people lack money and therefore live a ressource-based economy, with trash being part of their resource. A very natural behavior indeed.

Recently, a new concept has been promoted that should solve our problems connected to waste: The concept of ‘cradle to cradle’. The idea behind ‘cradle to cradle’ is that all our production should be made of harmless, easily biodegradable material.

Michael Braungart, one of the early proponents of the system, is looking for a society, in which wasting makes sense. And his idea is being celebrated as the next industrial revolution.

The concept suggests that we, the consumers, will not have to make any effort. We are not required to change our habits. Instead, the industry promises to solve the problem with new products of no environmental concern. And we as consumers will be allowed to proceed with business as usual.

Such a revolution is made for the industry, which otherwise is in serious danger to run out of business. Such a revolution is not for the people or the environment.

The idea of ‘cradle to cradle’ is nothing new. ‘Cradle to cradle’ is simply nature’s principle. Coming along to suggest ‘cradle to cradle’ as a new concept for industrial products should make the products commercially viable.

Waste does not need new ideas. The very idea of waste has to vanish. Both because the products should be of no concern for the environment, but also because products have to last and fulfil endless functions in the natural cycle of matter and energy.

One of the reasons that led to the great depression in the 1920th was that the market was saturated. Production, and therefore employment and buying power ran dry, because the market was saturated with sound products of robust quality. Products were designed to last, putting the industry out of business. But putting the industry out of business also put the money out of business.

In the 1920th, people were challenged, but did not succeed to free themselves from the commercial interest, maybe because they did not trust in the power of community. Or, maybe because the industry was too quick to prepare for a plan B: The idea of making industrial products planned obsolescent.

But this time we have all the tools to get this straight. This time we gonna make the money – not the products – obsolete!

Nature is rich and does not economize. But nature doesn’t waste. Waste by definition does not make sense in nature. But Michael Braungart is “seeking for a society were waste makes sense”. Another industrial society selling us, this time harmless waste, but still for money.

We need to find ourselves in nature instead of trying to imitate and remodel our man made commercial system with products that can be wasted with good consciousness. The abundance of nature we can only experience in nature.

Cradle to cradle is nature’s principle.

Trying to imitate it, we will most likely fail.

Doing it for money is criminal.

I have a serious problem with the idea of manufacturing solar panels. Solar energy has been the principle driver of all energy and material transformation on our planet. I cannot imagine that we will be able to design a more efficient system to capture solar energy than what evolution has developed for us and including us. The vegetation is the perfect solar panel. Removing the vegetation in order to make room for dead, unlasting technical devices to produce electricity can only be in the interest of the industry and money. The vegetation does not only provide us with energy, but with products of all kind. From food to cosmetics. From building material to clothing.

The technology and the solutions for our sustainment are right in place. We only need to share the knowledge about it.

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Maintaining the garden

There is a sheer iron resistance to the idea that farming can be done without heavy machinery. Hundreds of horse powers are out there on our fields. And people have completely lost confidence that it can be done otherwise.

However, maintaining a healthy garden gets down to one  simple  method called “chop and drop”.

Yes, we favor certain plants and crops over others that we call weeds. But it is a serious mistake to try to quantitatively remove those plants we have decided to call weeds. There is a much more simple, efficient and appropriate method than removing weeds with shoots and roots or even poisoning them with herbicides. We gotta change attitude and rather think positively of our crop than being afraid of the weed. You want to concentrate on taking care of your favorite crop, while you chop and prune some of the other plants that otherwise prevent your crop from fully developing. Following this practise, there no waste of any of the nutrients that had been taken up by the weeds. At the contrary: The weeds have – for the time of their own development – accumulated nutrients that are subsequently released for the benefit of your crop. Roots that remain in the soil decay – or at least partly decay, and enter the cycle of natural soil building right at the spot. And the arial parts of the weeds, when dropped at the place, cover the soil, preserve soil moisture and also contribute to the soil building. There is thus no serious competition for nutrients, because surface composting and root pruning recycle the nutrients to the system in favor of your favorite crops.

If you do not interfere in the garden, then it turns wild. Then eventually there is competition for nutrients and light, and certain plants take advantage. Then a succession sets in towards a climax vegetation typical for the particular climatic region. Proper gardening, however, is maintaining a young and open fruit forest. Pruning and chopping is necessary and sufficient to manage and maintain this stage for many decades.

Undisturbed soil is extremely potent in recycling organic matter. All the soil organisms needed for cycling are right in place. This is one reason why it takes a couple of years of transition when you change your practice from digging and tilling to a permanent non-dig garden. The soil fauna has to develop and reach its natural balance. Once you approach this balance, managing becomes easier and easier.

There is no real need to prepare compost other than composting directly on the surface. You may want to use larger patches of nutrient accumulating plants, such as comfrey, for surface composting at another place with the aid to translocate nutrients. But this is a soft and sensitive method which keeps pace with natural cycling for the system, allowing the system to proceed in its most productive form.

People often argue that slugs then take over and harm the cultures. But this is just another temporary problem, until things get into balance again. Firstly, slugs do not particularly go after your crop. They also eat what you chop and drop and thereby assist the composting process. Secondly, the slugs will be followed by their predators such as toads controlling their population. Ducks are an excellent garden keeper too eating the slugs and providing you with eggs. Every problem has a natural solution. No artificial measure can do a better job than inviting the natural predators into your system. Using poison will only address one problem for a short period of time while at the same time removing the basis for survival of the natural predators, pushing the system out of balance.

Modern agriculture is a synthetic system. It is hard to see for many, how to get out of the system. It necessarily requires some time and you may encouter a temporary break down of yield until nature gets back into balance. But yields recover, and takes over far beyond what can be done with a synthetic system. We cannot rely on a single crop anyway. So why not growing a rich mixture of crops together. Monocultures are only practical for the machinery we employ to cultivate them, but neither appropriate for us or nature. Mixed permanent cultures are far more productive and healthy.

Natural farming is about bringing back the natural players into balance. Once this is achieved, gardening becomes the easiest task ever. It is no more than chop and drop, chop and drop, chop …. and drop.

I reckon, once the physical primary work is done, I can manage 2 hectares and maintain them in a state of a paradies just as a single guard, while enjoying plenty of leasure time.

Imagine how much you learn by actually doing it!

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biochar oven

Efter at have afprøvet 3 forskellige versioner af ovne til at lave biochar, var vi mest overbeviste af den sidste model, som vi byggede sammen med kaospiloterne i Århus sidste uge. Derfor lavede vi vores egen i sammen stil i går ved Vadstedet i Christiania.

Denne model er kendt som “the everythingNice stove“, en hjemmelavet version af en “lucia stove“. Men vores version skulle blive en ‘scale up’ af den originale. Med hovedformålet at lave biochar, ikke mad.

Nu blev vores oven afprøvet i dag og det var en stor succes. En super ren forbrænding, og en ordentlig portion biochar som slutprodukt.

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Udover at “the everythingNice stove” brænder meget rent, så kan man fodre den med mere træ i løbet af processen, fordi det indre kammer, der hvor biomassen bliver til trækul, er åbent. Så: everything nice!

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