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Earth Bag vs Monolithic vs Cob  RSS feed

 
A. Soto
Posts: 34
Location: FL
books solar tiny house
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Hello!

I'm trying to consider types of structures I'd like to build, and the materials involved. This is a plan for 10-15 years down the road.

I've decided that, for my personal residence, I would like to build a domed structure. There are several advantages to building a domed house, but it seems to me that there is no clear article out there as to which materials are best.


Cob and Earth Bag structures look like works of art. Because you have almost complete control over how the end result looks, and you can practically do whatever you want with them, that customizable aspect of these types of structures is very important to me, because I would like to create my own house the very best I want it per specifications. They are very clean, effective and interesting types.

Monolithic Domes look pristine and are the types of structures used for emergencies, because of how much punishment they can withstand from the elements, and even I even saw a demonstration of ballistic integrity (guys shooting at a dome with different types of ammunition), and I was sold on the concept. You can customize the outside with whatever you want, and you get a clean, nearly impenetrable design. The downside I see to Monolithic is that, because of how resilient the material is, it can be very hard to reconfigure or, for that matter, customize during construction. Also, because of the methods and materials used, Monolithic is known to be more expensive to work with than something like Earthbags or Cob. Can't argue with centuries of integrity, though... that has to speak for itself.


But, I would like to get your take on the issue. Granted, I will probably be using all three of these techniques on my future plot of land, but this is for permanent residence. And because I intend to move to this land in a modified Airstream, I can take my time with construction without worrying too much about shelter and other essentials.


So let me break down the whole collection of ideas and situations, and specifications, so that I may reach a good conclusion.
---
I want for my Personal Residence:
- Dome Structure. Complete or Partial Dome (refer to image. This is a very lavish example, though)
- Almost complete protection from the elements.
- Customizable/Removable
- Environment-Friendly without sacrificing amenities
- 1000-1500 square feet
- Decent Insulation
- Total Cost of Construction: Under $15k preferred, $30k limit

Conditions:
- I will have time to build it
- I will find help to build it
- I will have saved some serious $$$ for it
- Am willing to combine techniques, like Earthbag innard, Rebar integration, Concrete or other outer shell
- Forested, Mountainous region with a clearing
- Choice of State: Wyoming first choice, Idaho second choice, Montana third choice, Washington (WA) fourth

----

I realize after doing some more research that the cost of Monolithics could get extreme, depending on the size and a few other things, but I'd love to hear your suggestions. Thank you!
 
R Scott
Posts: 3357
Location: Kansas Zone 6a
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How big are we talking?

How wild-fire proof do you want/need it to be?

Will you need/want to collect rain water for drinking/irrigation?

Cob and earthbag shouldn't be true domes outside the desert, but a round house with traditional roof.

Cob really needs time to dry before a hard freeze--so you will have a really short building season in some of the places you listed.

Cob and Earthbag both need proper soil mixes (although earthbag has a wider range of allowable mixes) and if you don't have the right clay/sand mix onsite, it can get really expensive really quick.

Don't forget the foundation!!! If you can do a rubble trench, great--but if you need a full concrete foundation you will use more concrete for just a cob or earthbag foundation than the whole monolithic dome. The thick foundation walls for cob, earthbag, or rammed earth are really prohibitive if you have to do them in concrete.



 
A. Soto
Posts: 34
Location: FL
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R Scott wrote:How big are we talking?

How wild-fire proof do you want/need it to be?

Will you need/want to collect rain water for drinking/irrigation?

Cob and earthbag shouldn't be true domes outside the desert, but a round house with traditional roof.

Cob really needs time to dry before a hard freeze--so you will have a really short building season in some of the places you listed.

Cob and Earthbag both need proper soil mixes (although earthbag has a wider range of allowable mixes) and if you don't have the right clay/sand mix onsite, it can get really expensive really quick.

Don't forget the foundation!!! If you can do a rubble trench, great--but if you need a full concrete foundation you will use more concrete for just a cob or earthbag foundation than the whole monolithic dome. The thick foundation walls for cob, earthbag, or rammed earth are really prohibitive if you have to do them in concrete.



Hmm... what is a rubble trench?

I'm talking 2 Bedroom/2 Bath, 1000-1200 square feet.

I'd like it to be very wildfire-proof. Hurricane/Tornado proof, Tremor resistant.

Yes, rainwater will be a function either attached to the house or established closeby.

Why should they not be true domes? Curious...

Ah, I see...
 
R Scott
Posts: 3357
Location: Kansas Zone 6a
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http://en.wikipedia.org/wiki/Rubble_trench_foundation

Wiki actually has good information on this.

If you have to do poured footer and wall from below the frost line to the top of the stem wall for cob or earthbag, the amount of concrete in just the foundation is more than would be used to build the entire structure with concrete block or monolith.

That is big/HUGE for a single dome for cob or earthbag. They lend themselves better to the multi-dome approach. Build a largish main dome then add small bed/bath domes to the sides.

Lots of plans like that at http://www.naturalbuildingblog.com/ and lots of good earthbag info.

The problem with domes and rain is the smallest crack in the outer layer can lead to catastrophic dome collapse from water infiltration. Domes need roofs unless you get very infrequent rain.
 
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