Green, cheap and efficient straw bale dome homes :)

[Jetijs]

Hi all
recently I have been obsessed with dome homes, like the ones here:
Monolithic — Home of the Monolithic Dome




There are a number of advantages of this type of home compared to ordinary homes, you can read about that in the link above. They use an inflatable air form, they inflate it and then spray polyuretane foam insulation on the inside walls of the air form, after that they put some armature and cover that with spray concrete. Simple and fast. We also wanted to try something like this, but could not find a company here that could make those inflatable air forms cheap enough. So the idea stuck for some time till I discovered the simple and elegant geodesic dome idea. There are many web sites online with geodesic dome howto's, diagrams and calculators. You simply get some wood bars, cut them to appropriate length and connect them together according to a diagram. The structure is very rigid and strong. It costs much less than an air form, is much stronger and does not need electricity and air pumps to keep it inflated constantly. A moderate V3 6m diameter dome can be assembled by 3 persons in about 2 hours, depending on the strut connector type. Here is our small test house geodesic dome skeleton and a small model in front of it:





We decided to combine the geodesic dome structure with the straw bale home idea. Using straw bales and clay as the walls. This is very cheap, easy and energy efficient. And this small hut is supposed to be a test house so that we can learn the process and make mistakes and learn. So far we have learned so much stuff what not to do Anyway. We dug out soil about 6m diameter and 0.5m deep, filled that hole with stones, gravel and sand. A perforated drain pipe was put underneath it all to drain the water out to the nearest ditch. On top of that we put the geodesic dome wooden structure with doors and began to cover that structure with straw bales:

[Jetijs]

After that you need to stuff all the gaps between the straw bales with straw and you are ready for the first layer of clay/straw mixture. The first layer is made using very liquid mix, so that it sticks good to the straw. You can not use thick mix for the first layer - it wont stick. Only when the first layer is done, you can begin with the next one.








This first thin layer is needed so that the next layer will stick better. With the next layer you use much thicker mix of clay, sand and straw and fill all the deepenings, voids and cracks till the surface becomes smoother like this:

[Jetijs]

Here are some pictures of the inside:




So far we have completed all the layers on the outside and are starting to work inside. When all the layers are ready, smooth and dried, the surface is covered with linseed oil and turpentine mix in three layers. The linseed oil penetrates inside the clay up to 5mm or so and when it dries, the surface becomes very hard and waterproof. The insulation properties of such a home are great, we have a heat wave here now and sometimes the outside temperature reaches 33 degree celsius, but inside the dome house it is nice and cool We have still much to do, but this is a fun project and if it will survive the winter, then we will start working on a bigger and better house. Overall this is really a cheap, easy to build and efficient house type.
Here are some very useful sites about geodesic domes:
SimplyDifferently.org: Home
Desert Domes - Home
geo-dome prefab geodesic domes

Will keep you updated on our success
Thanks,
Jetijs

[noises]

That's great, jentis. In round figures, what were your material costs like?

Lat year I saw some hemp cement dome houses in Yungaburra, on a licensed hemp farms up there. It was so cool to see a renewable resource being used in such an examplary and innovate way, right on the farm where the raw materials were grown. I mean, you can't go to a wheat farm and see a farmhouse made out of wheat, can you? As far as I know, she prefabbed the dome herself out of marine ply and sprayed the hemp-crete onto that (it weighs a lot less than concrete.) There's some other buildings there she built that are really quite incredible too, and they're modular and cheap. And an awesome permaculture garden she fed us out of.

[Chip Shorter]

Cool. Has anybody looked into underground houses?

[easyrider]

Oh My Good!

Jetjis, i m preparing to buy a piece of land and construct something identical to live in Romania, and i m gathering info for more than 3 years, and you have done it before me.
Very good, you have my admiration and all my atention.
We could say we are neighbours...
Please, do detaliate the process and the learnings, you could help us more than anyone.
Exactly this form of V3 6 m diameter is the one we choosed, with a height of 3 m.
We could not gather data on the resistance of the wood structure, of the load bering of the strawbales, and so on.
So, again, you could be of huge assistance to us...
So please more details, you could save lives... hours of hard work and a lot of money.

[Jetijs]

Hi easyrider.
The dome structure is very solid, it now supports around 3-4 tons of weight with all the clay and straw bales. The work is rather hard and weather dependent, if it is raining, you need to cover the dome with something to prevent water damage, if it is sunny, you need to remove the rain protecting plastic or whatever so that clay can dry better. You need to do all the inside and outside clay works before you can proceed to waterproofing the inner and outer surface. There is also always a possibility of strawbales beginning to rot and other difficulties, that is why you would need to build everything as fast as you can so that straw bales have no chance to get wet. A little wetness is nothing bad, it dries fast, but prolonged wetness can cause problems. This is a timeconsuming but fun project. We are constantly exploring ways of how to do this faster and easier. If you make a clay/water slurry sprayer, that will save you a LOT of work. Anyway, we are now thinking about using polyuretane foam insulation about 70mm thick instead of the straw bales, because it saves a LOT of work, it is faster, just few hours to cover the whole structure, it is rain proof and very light material. Its insulation properties is very great, 100mm thick layer of this foam is equivalent to 1 meter of brick wall. Also nothing can rot or settle down over time. You just need to cover it with decorative coat of UV resistant paint or plaster and that is it. The foam is very hard and firm, you almost can't press your finger in it, much denser and firmer than straw bales. Sure, it will cost a bit more, but that is well worth because it saves you almost 70% of the work you would do otherwise. I have calculated that if I went with the foam from the beginning, I would already be done long time ago and would have saved some money, that I payed my workers. Also it is not very common in our country to store straw in bales anymore, few farmers are doing this and with old and low quality machines. Most farmers roll the straw in a huge bobbins and this is also one thing in favor of the foam. You can get straw only seasonally in autumns or summer ends, but that is already too late for starting building, you need to store the bales properly through the winter. No such problems with foam. We will try to make a 12m diameter two story house using foam next spring, so far we have made a small scale experiment in this area and the results are very encouraging, here are some pictures:





This is a 3/8 V3 dome 1m in diameter. It was built from 20x20mm wood bars, then covered with mesh and sprayed with 10-20mm layer of foam. It is very strong now and looks awesome.

I have calculated that a 2 story house 12m in diameter with combined floor square area of about 150m2 would cost under 18000$ with all the windows, doors, decorative plastering and everything you need except plumbing and furniture. That is considerably cheaper than ordinary houses.


If you have more questions, just ask!
Thanks,
Jetijs

[easyrider]

Hei

Thanks very much for quich reply.
The thing is that i consider that the spray foam is very bad for human life, being a product rated for industrial use, like OSB, that came to civilian buildings but did not forgot the past.
Please search a lot before starting that way, you can not go wrong with the strawbales and mud.
All this new materials are rated to be used in civilian spaceas which use forced continous ventilation.
If you need workers, you might try with volunteers, like a was and the same way i will build for myself.
Here the time is stiil good for 2 months for this type of construction, and we still have machined strawbales.
Can you give me the site form which you took the way of connecting the triangles, and so on, maybe a scann of your project or something like this, the size in diameter of the wood and so on?

[Jetijs]

Hi
This foam is not toxic and does not pose a health threat. Of course it does not breathe, but the same is true if you make your clay/straw bale house waterproof from inside and outside using linseed oil. Anyway, you do what you think is best I will try to help as much as I can. For dome calculations I used online dome calculator from this site:

Desert Domes - The Dome Calculator

Also go through all the links on this page, very informative with lots of pictures:

SimplyDifferently.org: Home

[gerryalton]

Hi all,
I just need a bit of advice really, i would like to know where people suggest buying abroad as an investment.
I would like somewhere cheap, so Bulgaria is at the top of my list, as it is hot in the summer as well! does anyone have any recommendations?
Thanks

[beastman]

Jetijs can you give us an update on this? Have you have adapted/improved the design and could you perhaps give any further information on this brilliant looking build.

thanks

[FRC]

Great work Jetijs

Great work Jetijs, I have built two domes myself. The first, bigger one, is now
situated on my brother in law's farm. The second smaller one I dismantled later.
I did not use a regular geodesic design, instead I came up with a half-hexagon
type system where I was able to use conventional two by fours and nail them together without hubs. The two by fours are covered with shiplap, with sheet roofing material over that. It is movable, with dollies, since it was built on a round grainery floor. I was hoping to make it a small home with a loft but did not
complete the interior. This could still be done and moved to an acerage somewhere.

FRC

[beastman]

I came up with a half-hexagon type system where I was able to use conventional two by fours and nail them together without hubs.

FRC this sounds clever can you tell me how you did this? Better still is there a picture or drawing?

[FRC]

beastman

Sorry I do not have ant pictures or drawings. I will try to make drawings and post pictures. It involved cutting the ends of the two by four's on angles. I did not have a floor to start with, the structure was placed on the floor afterwards.
The base was rectangular sections nailed together to form a flat circle, then the
two by fours were nailed on to this circle. The top roof section was a hexagon.
If you draw a circle with 12 flat sides and then cut it half that is what it looked like from the side view.

FRC

[Jetijs]

Jetijs can you give us an update on this? Have you have adapted/improved the design and could you perhaps give any further information on this brilliant looking build.

thanks

Hi,
we are now in process of building a 10m diameter dome house. The foundation is being built right now. The wooden parts and connectors are ready, the windows in triangle form and the filling polistirol triangles also. When the foundation will be ready, the dome frame will be assembled, windows installed and the remaining triangles will be filled with polystirol foam. After that the guys with foam spraying equipment will come and spray additional layer of foam on the outer shell. After that, some decorative and waterproof plaster will be put on the outer shell. I have no pictures at the moment, but will post them as soon as I get some. In the mean time here is a model of how it will look: