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Paramo Permacultura Colombia - project for homesteading and education in the tropical highlands  RSS feed

 
Greg Amos
Posts: 40
Location: Colombia
2
solar trees woodworking
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Hi Permies,

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.

All the best

greg and angela

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2d view with rooms
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3d view
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lateral view
 
Daniel Ray
pollinator
Posts: 122
Location: Stevensville, Montana; Zone 4b
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What is the approximate sq. footage? Seems somewhat large for a starter project for two people, cob requires thinking small. I would also think about designing all water supply in one section of the house. Try to keep the kitchen, bath and wash somewhat close so you don't have to run as much plumbing.

Definitely insulate the roof. Cardboard, bottles, carpet, straw/clay works really well as insulators if your looking for low cost or free. What type of water barrier were you planning to use?

Sounds like an awesome project, gotta love cob.
 
Greg Amos
Posts: 40
Location: Colombia
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Hi Daniel,

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

greg
 
Glenn Herbert
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Location: Upstate NY, zone 5
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What kind of roof support structure are you planning for interior areas? Cob walls the thickness you show would not be strong or stable enough to safely support a green roof over that area. Spans up to 9 meters would require significant beams even for a lightweight roof, and truly massive beams for a green roof.

Given your latitude, average temperature and annual constancy, I think a green roof would not want significant insulation, as you will get a lot of solar input into its surface. Enough mass to carry the heat overnight should moderate it nicely.

I would advise designing the structure to build part first, leaving say the master bedroom, half bath and office for later. You can live in the other rooms and not be disrupted as you add the second set. This would be compatible with a structural inner wall to cut roof spans considerably as well. As a general rule, I would not advise more than about 5 meter spans between supports, and any main beams that carry other beams need individual support posts, not just cob. Is there any history of earthquakes in your region? If so, you cannot safely depend on pure cob walls for roof support but will need to have wood or other reinforced posts inside the cob that can carry the roof. What kind of rainfall does your area get in the worst storms? A low-slope green roof will have to account for all that water weight added to the earth.
 
Glenn Herbert
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As an architectural designer, I really like your overall organic shape and layout. However, the bathroom wastes a bunch of space to no particular effect, and you don't need to worry about minimizing exterior envelope as you would in a cold climate. Pulling the exterior wall in to move the bathroom functional space closer to the door would reduce the amount you need to build at first, and the master bedroom/office part can perfectly well have its own organic shape as an addition.

You have the sun directly overhead at midday and wide overhangs to protect the cob, so your windows are going to admit relatively little daylight without being bigger than cob wants to allow. I would consider having the high point of the roof at the center with a skylight, and the roof sloping away on all sides to ease sealing. This would also mean that all the exterior cob walls would not have to be too tall. An extra couple of feet/half meter of height require the wall to be correspondingly thicker. Support posts around this center would reduce the roof beam spans to manageable levels for a self-built structure.
 
Glenn Herbert
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I have done a crude photoshop modification to your plan to indicate the type of thing you could do. In reality, you would reshape the entire upper curve a bit to optimize those spaces, and give the second set of rooms its own curves.

 
Greg Amos
Posts: 40
Location: Colombia
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Hi Glenn,

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

greg and angela
 
Glenn Herbert
gardener
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1) Finishing the whole roof first kind of negates the staged building idea - you would have to fully support and brace the whole thing and leave part exposed to some weather until the second phase. As the walls that would separate the stages would be fairly close to the slope line of the roof, you would not have water pouring off the exposed edge, and some minor temporary finishing would give a safe edge that can be extended later.

2 & 3) Any roof surface that was not "green" or a solid rubber/plastic material would need to be higher slope than you show in your side view and thus make the center taller - nice for spaciousness and cooling, not so much for heating and constructing.

4) That strengthens my general inclination that it is better to have independent support for the roof. It will help construction anyway, to put up the posts at the inner face of your proposed cob wall, with diagonal bracing, and the roof structure and membrane so you can work on cob under cover.

5) Are the sunless times also the coldest times? If so, then you definitely want some insulation in the roof. If not, you will have to weigh the balance between spending real money on insulation that can work in your roof, and running the RMH for more of the year to keep the chill off.

6) Your walls will be massive enough that you may not need wall insulation. Using cob high in straw will make it more insulative.
 
Greg Amos
Posts: 40
Location: Colombia
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Hi Glenn, you just gave us a lot a great advices! thanks a lot for this.

our next step will be to read a good cob-building book, and then... well... start!

all the best

greg
 
Glenn Herbert
gardener
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Location: Upstate NY, zone 5
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Good luck! Let us know what you finally decide to do and post pictures as you go. We will be very interested to see the progress. And ask if you have more questions.
 
Greg Amos
Posts: 40
Location: Colombia
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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

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Daniel Ray
pollinator
Posts: 122
Location: Stevensville, Montana; Zone 4b
19
food preservation forest garden hugelkultur
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Hey, awesome to get some cob going and some great practice before starting your home.
You probably know this, but make sure you overkill rather than under do the thickness of your walls. Even for a practice shed, they seem a bit thin. Also, make sure you get the cob up on a nice high footer, you don't want the cob anywhere close to the ground.

You will learn a lot as you build with cob. I learned that everything takes twice as long as I calculated, I also had to do some major work to fix the door frames after finishing the walls.
 
Glenn Herbert
gardener
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Location: Upstate NY, zone 5
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Glad to see your progress! Cob is fun, though it is also a lot of work... er, exercise

I concur that your toolshed walls should be thicker, and most especially your house walls. If you do have the center as the high point, you can make the exterior walls only as tall as needed for doors and windows, and still have mostly high ceilings. This will allow sturdy cob walls with minimal thickness - say a foot to 16" at the base. Cob building books will have more authoritative dimensional recommendations.
 
Greg Amos
Posts: 40
Location: Colombia
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Hi Daniel and Glenn and all,

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.

Happy new year!

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House area December 2015, with cob stove in the back
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Toolshed with plaster and a tree :)
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Model
 
Daniel Ray
pollinator
Posts: 122
Location: Stevensville, Montana; Zone 4b
19
food preservation forest garden hugelkultur
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Hey, great and good luck with building and leveling. I know the pains of hand digging. If you're going post and beam then wall thickness isn't a huge issue as the stress will be on your posts rather than the walls themselves. I still suggest the thickest walls you can manage though, they have benefits other than structural integrity--aesthetics, sound proofing, thermal benefits-- I think your idea of having the posts outside of the walls is smart. Cob Cottage company's cobweb books have an article that discusses embedded beams causing weaknesses in the wall and cracking from the different thermal expansions of those two materials. If you can get your hands on a copy of those books I highly suggest it. Good luck getting your permit and building your house!
 
Greg Amos
Posts: 40
Location: Colombia
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Hi there,

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?

Any other recommendation?

thanks a lot

all the best

greg
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Top: beams, bottom: beams and purlins
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Sideview with the 4 main posts, and roof.
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the new shape of the house
 
Glenn Herbert
gardener
Posts: 2180
Location: Upstate NY, zone 5
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The longer you can make the continuous beam sections, the more rigid and strong the assembly will be. If you can make up VC-02, 03 and 04 from only two beam timbers, do it.

Post-to-beam connections are always stronger if the beam is on top rather than at the side of the post. The beams should be at least spiked to the posts, if not actually joined by mortise and tenon.

You will need some diagonal braces to keep the frame from collapsing while it is being built (before the cob is in place to steady it), and braces will be helpful even after completion.
 
Greg Amos
Posts: 40
Location: Colombia
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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


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Lifting the beams with pulleys
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Attaching the posts to the beams
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The first rafter
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The situation in May 2017
 
Burra Maluca
Mother Tree
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Greg Amos wrote: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


I've made it show up in several forums, with 'projects' as the main one. 

Would you like the title to be changed a bit too?  Just tell me what you think would be best. 

Also, the photos in your last post aren't showing up. Might be that they're no longer there, or maybe the permissions are set wrong. 
 
Greg Amos
Posts: 40
Location: Colombia
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Hi Burra, thanks a lot for your help!

I will attach the photos, it works better.

Yes, I'd be grateful if you could change the title a bit. Maybe something like: "Paramo Permacultura Colombia project for homesteading and education in the tropical highlands".

All the best



 
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