We are finishing our cob house in Colombia webpage, and a very important part of it is rainwater harvesting. So we decided to try to build a eartbag tank.
First we build the concrete slab. Then we build 10 layers of bags. It can hold 5000 litres. Next steps: cement plaster inside, cob plaster outside. Roofing... we don't know what kind of roof it will be. An almost flat green roof would be nice.
More than a year has passed since the last post, time to put some updates! We have been quite busy, with travels, design consultancies and permaculture workshops, but the work on the house is going well.
In July 2018 we more or less finished the interior walls. Then of course because the shrank, we had to refill the top part between roof and wall 2-3 times, quite an exhausting job, given that you have to work around rafters and beam. If we had to do it again, we would definitly build all the walls (interior and exterior) at the same time, to ensure better cohesion, and faster drying.
In March 2019 we covered the roof. In order to keep it as light as possible, we put sod (actually more grass than soil) directly on the HDPE membrane in some places, and gravel in others, so we could create a kind of drainage. It has rained a lot since, with hail and everything, and nothing happened: no collapse, no rain inside, so I assume it's safe to say the roof is sound
We also finished the floor. First we put the basic layers: gravel, vapor barrier and cob. It was not so great to put cob, as it shrank and cracked and was quite uneven... the best we could do was filling the largest cracks, and then we put the final (for now) layer: a lime mortar made with 1 part hydrated lime and 3 parts sand. We bought the lime in a local producer, and the quality was quite different between bags. Some produced a very nice and smoot layer that did not crack, while another batch would crack a lot and even had some kind of bubbles popping up. Now the floor is quite ok, strengthening by the day, but we will probably cover it with a water-based epoxy paint or resin for durability and easy cleaning.
We installed the electric system, which consists of a 100W solar panel, a charge controller, a 65 Ah 12 V battery and a 600W inverter. It works like a charm, we have no problems working all day on the computer, plus watching 3 hours of shows in the evening. LED lights, computer and phone charging are our only requirements for the moment, but we may have a small fridge or coolbox in the future, as well as a water pump and maybe a small washing machine.
We finished covering the outer part of the exterior walls with what we call "sticky plaster": 1 part sieved soil and 1 part cow manure. It provides a protective layer, which is also somewhat waterproof.
The interior walls were also covered with the sticky plaster, and then, because it is very work intensive to apply a clay plaster, as we previously did with the interior part of the exterior walls, we decided to paint them with limewash. We bought a better quality lime, called "type N" and put 2 coats on all walls. It looks great. The transition between the cream colored clay and the white limewash is also nice.
Finally we brought some furniture: gas stove, kitchen, table and chairs, as well as a bed.
We also advanced with the garden.
Next steps: finish the shower, which currently has a lime plaster. We will either put an epoxy on it, or a sealant they use for concrete water tanks. Then finish the water tank, and install the water system. Hopefully by the end of January we will have everyting done (even if the tank might not be full, as the dry season will start soon).
I am going to buy the last piece of my solar kit: an AGM battery (12V, 100Ah) (the other elements are: solar panel 100W, a 300W inverter and a 20A charge controller), and I am now a bit confused about where to wire the inverter.
1) According to Renogy, you should NEVER wire the inverter to the charge controller, but to the battery.
2) According to this video it is better to wire the inverter to the charge controller.
thanks for your appreciation To be honest, from time to time we are in awe too. Now that we are building the inner walls, which are thinner and lower than the exterior walls, we keep thinking: "how were we able to build those huge exterior walls, only the two of us???" It must be the magic of cob. And the luxury to have the time to do it.
We put the HDPE membrane on the roof just before Christmas, and after some heavy rainfalls, there are no signs of leakage.
Even though we designed 4 skylights, in case it was going to be too dark inside, now that the membrane is installed, a lot of light enters through the windows, to we will leave the skylights close. It will be easy to cut the opening in the future, sould we require it.
The next steps are: building inner walls, putting grey water pipes, floors, plasters, building a ferrocement rainwater tank,...
Rene: Thanks for your honesty better safe than sorry. The structural engineer calculated a load of 130 kg/m2 for the roof, with the rafters size we are using, so you're absolutely right, we need to keep the soil layer as thin as possible. Metal roof could be an option, but I do not like them that much. I would prefer going with some 3-5 cm of soil, mixed with gravel. I calculated that a layer of 5 cm of wet soil weighs about 80 kg/m2, so I do hope we are safe with it.
Jeremy: in workdays, let's say about 60 to build the cob wall, 6 hours/day, 2 people. (and an excavator). What we spent so far. Stones and gravel for foundation: 200$, wood boards for frames and roof 400$, excavator for cob mixing and leveling 500 $, HDPE 400$ so in total around 1500 US$ so far.
We've been busy the last 6 months, and now is time for a little update.
In August, we finished to build the roof of our cob straw house. We were quite happy, putting all the boards, and then covering them with a 40 mil HDPE membrane, and some gravel for the green roof.
As you may notice in the second picture, something very VERY important is missing... And a Permies contributor, Glenn Herbert, did mention it... Unfortunately, I did not pay enough attention to.... CROSS BRACING!!
Well, what had to happen... just happened. On August 16, the roof felt down... Fortunately, without damage for us (I was on the roof, my wife under it, she noticed someting was wrong and could escape just in time...).
After this unfortunately event, we decided to 1) bury the posts (not let them standing on stones like before) and 2) start building a thick cob wall.
We started the next phase of our cob straw cob house in September, and we are nearly done. We started mixing the cob by foot, but with only the 2 of us, it takes a lot of time, so we asked an excavator to come and help us, and it really helped (it mixed in 3 hours what we had mixed in 3 weeks...).
We are rebuilding the roof right now, and honestly, it feels much more secure than before.
We hope to finish the roof before Christmas, so we can move in for New Year (good thing we are in the Tropics: no dead season).
Hi, I've used a ceramic water filter in Nicaragua for 1 year, and I've been very happy about it. The one I had was coated with colloidal silver, to increase efficiency. Now I'm going to live off grid in Colombia, and fortunately I will be able to buy one here again.
Hi there, time to put some news of our project. Actually, I'd like to move this post from the "cob" to "project" forum, as we decided to change the building material a little bit, and build with strawbale. Also, I'd like to add the other stuff we are doing in the farm, that has nothing to do with cob. If someone knows how to do it, I'd be very thankful
We finally got our building permit, and now we are building the round timber frame for the green roof. It takes a bit of time, as we are only between 2 and 4 people, without electricity, but with much ingenuity!
We started with lifting the beams with pulleys and with a kind of pulley used in car workshops to lift motors (I don't know the name in English).
Then we put the beams (previously charred using the Yakisugi method) on stones under the beam, and attached them to the beam.
Once we had all beams and posts in place, we continued with the rafters
And now we are in the process of putting the rest of the rafters
We attached the beams to the huge posts we used for the pulleys, in order to secure them. The base of those posts is 60 cm deep into the soil, so they are not going to move.
There are not many joints as for now. The beams "fit" on the posts thanks to a simple V-shaped cut. The rafters have a simple joint to fit in the lower beam.
There are some "diagonal" beams, which will require some more elaborate joints, we are doing them right now.
So, as for now, the frame is made only of natural material, we used no concrete, not even a nail
finally we applied for the building permit!! we found a good architect and civil engineer who helped us with the blueprints.
Now we are trying to figure out how to join the different posts and beams together. As you can see in the images, some unions could be tricky. We will use eucalpyptus roundwood.
The posts diameter is about 20 cm, while the beams diameter is about 15 cm.
We plan to build on the floor the 4 main sections (VC-01 to VC-04), and then rise them up, and on the top put the 3 remaining parts (VC-05). The exterior beams (VC-06 to VC-11) would be placed at the end.
For VC02, VC03 and VC04, we are wondering whether to use 4 beams per section, only 2 beams, connected on the central post?
Do you recommend to put the beam on the top of the post, or on the side of it? what kind of joint would you use?
My wife and I have a farm in the Colombian highlands, and as some of you may know, the country was hit recently by a severe drought event. In order to be more drought-proof, we decided to hire (April 2016) a backhoe to dig us a pond, which would be connected to a swale.
We first marked the pond perimeter, which has a rectangular shape, about 8m long, 4m width, and 3.5m deep (for the deepest section). The soil has a high clay content, which is good for sealing.
The terrain is quite flat, therefore we just built a small dam.
The backhoe driver already had experience making ponds, which may explain why he dug the side walls so steep. That was actually my concern: I thought the side walls should not be so steep so the backhoe could drive back and forth on them to compact them. In this case, the driver just used the shovel of his machine to "compact" the walls.
My concerns were not justified, as a few days later the pond was half full, and now it's almost totally full, probably by a mix of runoff and groundwater.
As for now we did not see any overflow from pond to swale or vice-versa. By the way, the spillway of the whole system is located in the middle of the swale.
What do people with experience with this kind of earthworks think about it? was it well done? would you have done it differently? I guess we'll have to wait until the next dry season (December-March) to see if there is any infiltration.
thanks for the advices, indeed the wall thickness of the toolshed is too small, and of course for the house walls will be thicker. Actually we read in "the hand-sculpted house" that a circular shape is more stable and allows a reduced wall thickness, so we decided to try it with the toolshed, and so far it still stands A proper roof is still missing, we want to try to make our own clay tiles...
Also we will build a higher stone foundation for the house, really this toolshed was an experiment, and we did not take all the care requiered for a proper cob building.
As for now we are in the final steps of levelling the terrace for the construction. It takes time, because we do it with human power only, but actually it's ok because we are still in the process of getting a building permit.
A friend of ours is architect, and he helping us with the official part of blueprints and civil engineering paperwork. Incredibly, earth is not officially recognized as load-bearing material in Colombia, but fortunately wood is, and as we plan to start building the shell with posts and the roof structure, and then fill it up with cob, that'ok. You can see a model in the photos below. We don't know yet if the posts will be partially embedded in cob, or outside the structure, but probably it will be the second option, so we can put a hammock
We are very excited to try natural ways to fix and treat our eucalyptus roundwood posts. Jay White Cloud is an awesome source of inspiration in this regard. To fix them, either cobblestone foundation, or in the soil. For wood treatment, Yakisugi sounds very good.
Hi there, finally we did start with the construction. Not directly the house though, but a little toolshed that allowed us to test our material and become more familiar with cob building. It was great fun to do it, and fairly quick also: about 20 days, 4-5 hours per day, 2 people. We did learn a lot of stuff, like to brace well the door frame, unless we want a funny entrance... We are now waiting for the building permits, and will start our house soon
Hi Darren, I'm one of your old students (Greece 2010) and very happy I took this PDC with you.
My question is about keyline, a technique you said that works well to increase water infiltration on broad acre. A friend of yours in Latin America, Eugenio Grass, is giving keyline courses to poor farmers, and I'm wondering how relevant it is for a poor farmer to learn something as tricky to implement as a keyline system with a Yeomans' plough. Unfortunately, I have to bring swales in the discussion to make my point ("unfortunately", because I know there are kind of opposing schools).
1) Intellectual understanding. Let's face it: it is much easier to teach how to define contour lines, rather than keylines. With contour lines, you just need an A-Frame. With keyline, you need to teach topography (how to find the keypoint), then A-Frame to define the keyline, then a way to define the lines downside and upside of the keyline, parallel to it.
2) Hardware. Did you try to make keylines without a tractor? I do not think that's possible. While this is not a problem in rich countries, poor and small farmers in many regions of the world would NEVER be able to even rent a tractor to do the keyline plowing. But then, why does Grass teach in regions like rural Nicaragua (where I've been the past year)? A swale, at least small ones, can be done by hand, and if the farmer has some money, it's cheaper to hire people than a tractor.
3) Cost. I don't remember exactly the numbers, but during the PDC you said the cost for 1 m of keyline is something like 0.5 cents while 1 m of swale is 2-5 cents, meaning it's way cheaper to do keyline. What is missing, is that you build the swale once, but you have to use the yeoman's plough once a year during at least 2 years, most probably during 3 - 4, so at the end the costs are similar.
4) Ecological biodiversity. When I see images of broad acres with keyline, I miss the trees! Yes, you may increase water infiltration, yes, you may get better pasture, but at the end of the day, it's still a huge piece of land without trees... By the way I have the same issue with holistic management: huge and fertile pieces of land, but no trees on sight. The only notable exception is when you plant trees using a keyline geometry: that looks wonderful! The nice part of swales is that they are a tree growing system.
So, for all those reasons, I would not recommend keyline plowing to people who don't have money, or who have difficulties understanding abstract stuff, like how to identifiy a keypoint (and during my teacher's training, I've seen a LOT of people with a PDC but no idea about how to identify a keypoint). But maybe I'm wrong, and I'm looking forward to hearing your comments
@ catlow: will an anaerobic process still occur if the bucket is not airtight? I am interested in exhausting all low-tech options before considering a commercial model.
@ Lisa: I LOVE the system you guys promote! Just a question: how do you lift the batch once full?
@ Jennifer: that's a very nice way to solve the pee issue.
@ Fred: I was considering any city. I personally live on the land, so I have no problems to process humanure, but there is a 8 million people city (Bogota) not so far away, which means a LOT of potential clients for such a system
I also feel Geoff is investing less time in his Q&A this year. They are still super interesting, but did you listen to the ones about Methods? He said twice "all those questions have already been answered" probably meaning in the comments sections. That's something he did not do (so far) in 2013 or 2014. Actually I'm ok with that, if he considers that questions have been answered in the previous years, because I see all videos, but I don't read all comments. Anyway, as long as he keeps relaxed when answering questions, I'm fine.
By the way, the bonus courses earthworks and reading the landscape are also part of the 2015 course. And we will have access to the online content until December 31 2015.
I also wish old students could come and help people who have super specific questions about their piece of land.
Apart of that, great course! looking forward to learning more about earthworks
Do you old students have access to the online PDC videos right now? I'm wondering because as he gives an extra bonus every year (first, earthworks, now reading the landscape), it would be nice for old students to be able to see the extra bonus as well.
Hi all, I'm looking for a cheap, clean and efficient way to use a dry toilet in an apartment in a city, without access to a larger compost pile where you would dump it once full.
I was wondering if using a 15-20 liters bucket, just adding sawdust, and then closing it and letting it decompose somewhere below a table, would work. The bucket number used would be about 15-18 per year.
Only small amounts of pee would go in this bucket. Pee would go in another bucket filled with sawdust.
Only one/two people would use it.
Worms could be added to speed the composting process.
After one year or so, the compost would be put in a nearby park to fertilize the trees.
great suggestions! thanks a lot for taking the time to photoshop the blueprint! May I do some comments/questions:
1) we love the idea of building in 2 phases, finishing the master bedroom, office and extra toilet later. I guess we would probably finish the roof for the whole house, then add those 3 rooms. Any recommendation about this?
2) we love also the skylight. Actually we did consider putting one, then discarded the idea because we thouht we would loose quite a lot of heat, but it's easy to build a sort of curtain to close it overnight.
3) we love the idea of a circular roof around the skylight. In our context, would you consider another option for the roof, like wood or anything else?
4) there are no earthquakes record in the area, however there is a strong earthquake region 400 km away, and some shaking can be felt sometimes. We don't know how much rain falls during the worst events.
5) there are times of the year without much sun, which means no heat in the roof mass, does it mean insulation is a must?
6) what about walls insulation?
Thanks a lot Glenn, looking forward to hearing from you
IMHO we should try to avoid putting dams in permanent creeks and rivers, as they can block wildlife. (agreed, with a good design and a well-placed spillway, this should not happen). This is why I like the idea of a belowground pond. Also, in case of a 100 year rain event, because there is no dam, then there is nothing that can be destroyed.
I wouldn't consider this technique for a large pond with potentially serious consequences in the event of a failure
mmh, what could be the serious consequences?
Then for the upstream part of the pond: if I use an excavator, then I would not be interested in the slow erosion process where the water enters the pond, maybe I would do a sort of backcut (to avoid the waterfall) so that any wildlife (fish) can continue to swim upstream. In other words, the water stream after the earthworks would continue as before, just passing through a pond that was not there before
Thanks you, again, and best greetings from Latin America,
width is 15 m and 9.5 m deep (front to back wall). Area is more or less 100 sq meters, that is ca. 1076 sq feet.
Thanks for your advise, yes, the house is sort of big, we will probably start with a smaller project to gain some experience, like a cob dry toilet.
Plumbing... we thought a lot about putting all water supply together... we are sort of between to small hills and may build a water tank on each of them, so each section would have a separate water supply.
For the roof, the water barrier will probably be some plastic membrane (the only unnatural part with the plumbing, but how to avoid it? the flatter the roof, the more tricky it gets)... thanks for the advice about insulation, straw and clay sounds good
Hi Zach, nice to have you here. We (my girlfriend and I) have a small creek flowing in our land, and we would like to build a large pond. There are 2 options: putting a dam, or making a below ground pond. I prefer the second idea, I seems more natural to me. I can imagine something like this:
Also I very like the natural (and slow) way to build it, I was planning to dig the pond, using the clay to build our house. The question is: how to best avoid erosion where the water falls into the pond? Indeed, I expect to create a 0.5 to 1 m high fall, and am a bit concerned about erosion problems. I was thinking to 1) put logs, like in the link above, and enjoy a waterfall 2) put a flow form or 3) avoid the fall by creating a gentle slope starting 5-10 meters upstream, with some kind of "stairs" in case the slope is still too steep.
What do you recommend? When it rains, the small creek can grow, but not too much, as the watershed is not that big and the soils quite good. By the way, I'd love to know what you would recommend if the creek could grow big, like in dry/arid places and destroy any logs or flowforms we put in.
Hi Chris and Linda, nice to have you here, we (my girlfriend and I) plan to build a natural house near Bogota, Colombia. It's in the tropics, but it's not hot: 14°C average, at 2600m above sea level, 900 mm precipitation quite well distributed during the year. Nights are usually cool year-round (5°C) and days warm (25°C). It's like a permanent central-european spring (or autumn). We want to heat the house somehow, in order to enjoy the evening reading books or playing, and to use the sun seems difficult, as we are close to the equator, and the midday sun is often vertical above the house. By the way, we have a design of the house in the cob section. So, here are the questions:
1) which natural material do you recommend, considering that we have clay and wood easily available? we strongly consider building a cob house.
2) if we build a cob house, and use a rocket mass heater to heat it, do you recommend to insulate to walls outside?
3) what kind of roof do you recommend? we strongly consider green roof.
4) is it ok to build a green roof with a 2° slope? the front wall would be 2.5 m high, the back wall would be 2 m high.
5) what is the insulation capability of a green roof? do you recommend, in our context, adding extra insulation?
7) what is the best way to make the exterior plaster waterproof (against rain) as well as the walls where the shover is.
Is our context, would it be more easy to make a earth floor, or a wooden floor?
9) we would like to build a small storage cellar inside a hill, just outside the kitchen, any idea how deep it should be, and the best way to avoid rodents eating our food? How to prevent any moisture/water infiltration?
Wow, so many questions! don't worry if you can't answer them all thanks a lot for you help!
my girlfriend and I are going to build our cob house in the Andes of Colombia, near a place called Paipa, which has a temperate oceanic climate (Cfb, like London or Seattle an average temperature of 14°C (day around 25, night around 5, year-round) and 911 mm of rain, without dry months.
We are just starting to think about the design, and would love to get advices or tips. One interesting challenge is that even though we are in the tropics, we are in the high tropics (2600 m), and nights are cool/cold. It would be nice to go solar passive, but... the sun just passes above us most of the year, there is no way we can use the midday sun to warm the house (unless we put a transparent roof). So we want to build a nice RMH in the center of the house (and another reason to support the kickstarter Oh, and against to wall would be a rumford fireplace, we would connect the pipe of the RMH to the one of the fireplace to have only one pipe outlet.
We also would like to build a green roof, and are wondering whether to insulate the roof. you can see in the images below that the roof would have a small angle, and rainwater would be collected in a water tank behind the house.
The outer walls would support the roof, while the inner walls would be thinner, just separating rooms.
We want to use a dry toilet system, probably one with bucket/barrel that we leave decompose outside. Not sure yet about it. We want something that can be replicated in big cities like Bogota.
We'd like to have a small greenhouse where the shover is.
Water from kitchen and bathroom would go into 2 greywater systems.
The door in the kitchen would lead to a small hill, inside which we plan to build a small storage cellar for food. Anyone has done it?
Ok, we will keep posting here the construction process, which should start in August.
I'm so happy there are enthusiastic people around to promote permaculture teaching.
Congratulations to Matt Powers (and thank you Permies for reaching his goal in only 4 days!
Rowe Morrow's digital platform is also on good tracks: 10'100 $ raised, only 5000 left! and 11 days... and then ANYONE with permaculture experience will get tips and tools to share his/her knowledge with others, and that's great!
Hi everybody, I wish all of you the best for 2015, and beyond.
The campaign to get Rosemary's knowledge for free online needs your support. Imagine how lucky we are: thanks Geoff Lawton, it's possible to get a PDC online. And for those who feel like teaching, it would also be possible to learn how to be a permaculture teacher online, for free. Any place worldwide with an internet connection could thus become a small hub for permaculture dispersion.
Hi everybody, I'd like to share Alfred Decker's message:
The campaign went online today: http://www.wethetrees.com/campaigns/rosemary-morrow-s-teaching-permaculture-teachers
Thanks for all of your feedback and comments, they were *very* helpful!
We need your help to make a successful campaign and to build the platform. Once we have accomplished this as a base, we can look into translating the materials into other languages and doing outreach to people and places that can really use the information that will be made available for free download.
Aside from making a donation, here is how you can help:
* Share the campaign and Facebook pages <www.facebook.com/groups/rosemarymorrow> widely through your personal and professional networks. Write about your experiences with Rosemary and why her empowering teaching methodology is so valuable.
* Email your friends and family and propose to make matching donations, especially as holiday or birthday gifts.
* Translate the campaign text into different languages and distribute it with a personal comment from you.
* Post photos and comments on the Facebook page.
If you have other suggestions on how to help the campaign, please send them along!
Happy solstice and holidays, and thanks for your time and energy,"
I had the chance to take a TT with Rowe, she's an AMAZING teacher. This another great online initiative will for sure increase the speed of dispersion of permaculture worldwide. Thumbs up