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dirt bag structures | (Read 1258 times) |
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paul wheaton
Administrator
Posts: 1343
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August 14, 2007, 08:07:22 AM |
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I'm guessing that these have really poor insulation. Anybody know?
Anybody tinkered with this kind of construction?
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pixelphoto
Posts: 44
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August 23, 2007, 11:04:56 AM |
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I would think they have good insulation.
the underground houses use earth mass to maintain a constant temperature.
I would think if they had enough mass the earth bags would keep the inside pretty stable.
just my thinking out loud. I could be wrong.
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Jeremy_IL
Posts: 53
Workin' Central IL converted farmland
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August 23, 2007, 01:57:34 PM |
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I'll follow Pixelphoto's lead in thinking out loud:
I guess my question would be how are the junctions sealed? Maybe I'm thinking too simply, but the implication of "bags" seems to bring to mind "holes."
Pixelphoto is right in that the monolithic dirt structures are great (like caves), but they're just that: monolithic. No crevices/cracks for air to ruin the insulative value. Much like insulated concrete forms and pouring all the walls to your house in one pour. No way to get air infiltration.
But I'm imagining something like sandbags (or dirtbags) stacked up, with little fissures for air to infiltrate. I'm probably simplifying this too much (likely), or I just have no idea how these things work (more likely).
-Jeremy
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paul wheaton
Administrator
Posts: 1343
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August 24, 2007, 10:17:19 AM |
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These structures usually get some sort of final coating of something ... don't they? So the dirt bags provide the structural support and then the coating ...
I wonder if the dirt could be filled with a mix of cement and dirt. Then when you are all done building it, you could just spray it with water ...
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Jeremy_IL
Posts: 53
Workin' Central IL converted farmland
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August 24, 2007, 02:06:43 PM |
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Interesting link:
Looks like they're finished with stuff like Adobe...
http://www.networkearth.org/naturalbuilding/honey.html
(from above)
"Dense materials such as adobe, and rammed earth have R- values roughly equivalent to 0.25 per inch... yet despite this low R-value, earthen walls function as an absorbent mass that is able to store warmth and return it to the living spaces as it is needed. This has been documented as the thermal flywheel effect and is referred to as the K-value. This substantiates the common experience people feel that an adobe house is "warm in the winter and cool in the summer." [The "effective R-value" discussion depends enormously on climate and the thickness of the mass. –ed.]"
Looking at the work-in-progress scares the heck out of me as far as stability! (if you go as fancy-schmancy as these guys)
-Jeremy
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paul wheaton
Administrator
Posts: 1343
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August 24, 2007, 05:03:47 PM |
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All the stuff I have ever seen on using dirt bags has been for smaller structures. I wonder if it is ever used for something larger.
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permaculture.dave
Posts: 113
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January 17, 2008, 04:43:10 PM |
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If you just fill the bags with plain old dirt I suspect you'll get more bang from the thermal mass than the insulation quality. If you want to increase the insulation value of the dirtbags perlite would probably be a good solution.
For better heat retention I would probably consider using the heat-retaining dirt on the south side and the more insulative version on the North, East, and West.
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alexisavoire
Posts: 120
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March 07, 2008, 05:42:26 PM |
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Sink the foundation, use the dirt bags to build a partial wall with a low roof. Roof should almost touch the ground. Minimize non-natural elements like plastic. Combine sod house structure with dirt bag construction and there should be reasonable insulation. If you combine the solar panel lined sod roof with sod double walled insulation this would make a pretty comfortable and cheap home. Pacific Northwest, the ground isn't that friendly to sunken construction in most places but if you choose toward the ocean you can get your new home to work with the damp, mossy environment instead of rotting from it. If you build in a stone and cement fireplace you have a great warm place year round. Dirt bag contruction by itself does not hold heat well. It is cheap and quick though.
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MJ Solaro
Administrator
Posts: 131
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March 08, 2008, 10:56:41 AM |
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pic of a finished dirt bag house:
There are plenty of finishing options: a stabilized earth seal, lime cement stucco, adobe, etc. but yeah, you generally don't leave the dirt bag house open to the elements...
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SueinWA
Posts: 313
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October 14, 2008, 01:06:11 PM |
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Go to the website of the man who has done more for earthbag construction than anyone, Nader Khalili. See his site at http://www.calearth.org/
His initial idea was for survival domes that could be erected in a day or two with simple materials: a shovel, a stack of sandbags, and a roll of barbed wire.
Here's how they're built:
Using a string and a stick and some lime or something, mark a 10- or 12-ft circle on flat ground. Start digging inside the circle and use the loose soil to fill the sandbags. Place the first layer of filled sandbags end to end just outside the marked circle. Leave a gap one or two bags wide for a doorway. Cut and lay two lengths of barbed wire on top of the first layer of sandbags (like railroad tracks), then stack the next layer of bags on top of the barbed wire.
After you've gone a few bags high, start to gradually stack the bags slightly inward, as you want to form a dome structure. Be sure to add the two rows of barbed wire between each layer of bags so the barbs catch on both the top and bottom bags. Continue to allow for the door.
When you're finished, your shelter will be partly underground and partly above ground. Frame the doorway and add a door or a piece of canvas (etc).
In a survival situation (such as after an earthquake), just shovel dirt over the shelter to protect the sandbag fabric from UV damage. You can also cover the dome with plastic sheeting and then cover it with soil. You can also cover the dome with a fairly thin layer of concrete.
In areas of high rainfall, I would cover it with plastic/soil or concrete, and add a surrounding apron to keep the hole as dry as possible.
In hot/dry areas, you could cover the dome with earth and plant with clover or other plants to shade the soil and keep the interior cool.
Keep in mind that adobe homes in the hot Southwest absorb the heat of the sun and release it at night, but often the nights are hot by themselves, and the homes really don't need that extra heat, day or night. Old adobes were built very thick, to the point that the sun couldn't completely heat up the exterior walls, and the interiors stayed cool. Due to labor issues, many new adobes are only a foot thick, and have considerable cooling issues.
While these domes started out as survival shelters, the design has been advanced to regular homes. These domes are very earthquake-stable.
Personally, I would really love to build a small dome and use it as a root cellar, with a thick layer of soil over it for insulation. All I need are a couple of muscular, non-lazy high school boys to dig it for me....
And it seems to me that these would make pretty good shelters in Tornado Alley (thickly covered with soil and planted, so the wind couldn't get a grip).
Sue
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WenVan
Posts: 28
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October 22, 2008, 09:39:46 AM |
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I can't wait to show this info to my husband! He is always keen to know about alternative construction.
I am too...but I must say, the subject of "Dirt bag structures" made me chuckle (a little) to myself. It sorta sounds like a home for "dirt bags". Sorry...I just couldn't help it! 
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SueinWA
Posts: 313
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October 22, 2008, 11:23:44 AM |
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Actually, most people refer to this method as 'sand bag' or 'earth bag' construction. This was actually the first time I had seen 'dirt bag' since I heard that old joke about 'the difference between a Hells Angel and a vacuum cleaner is the position of the dirt bag'.
I understand that some places in Tornado Alley have a rather high water table. For a case like this, you could import your sand (cheaper than topsoil, by lots) and start building right on top of the ground, or only digging as far as you felt was appropriate. I would make sure that the entrance didn't have anything the wind could grab, but I'm sure your husband knows more about tornado shelters than I even dream exist.
Just be sure to cover it -- I wouldn't go less than a foot, and more would be better. And be sure to blend it in with the landscape, shapewise, so the wind would be more likely to just flow over it. Plant it with something with a very extensive, dense root system, like clover.
Here I am, visualizing a sandbag dome, uncovered, being hit by a tornado, with filled sandbags being tossed all around....
Sue
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SueinWA
Posts: 313
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November 06, 2008, 11:25:28 AM |
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I was under the impression (right or wrong) that wind needs something to catch hold of to peel up a flat surface like asphalt. You know how difficult it is to pick up something very thin that is being held to a surface with water. If you can't get your fingernails under it, it's almost impossible to pick up.
But I may be mistaken.
But the odds are probably better that you would be hit/indirect hit by one of the smaller, less powerful ones. And if you had a sandbag shelter covered with a foot or more of soil, and planted, it might increase your chance of survival considerably. These sandbag shelters have been tested in the earthquakes of SoCal and come out very well indeed.
When I drove across the U.S. some years back, I was shocked at how many mobile homes there were in Tornado Alley. And none of them seemed to have any kind of visible underground shelter nearby. These sandbag shelters could make a big difference in chance of survival, not to mention peace of mind.
Sue
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SueinWA
Posts: 313
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November 09, 2008, 09:44:00 AM |
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Tornadoes sound so scary to me that I wouldn't live there unless I had a hidey hole really close.
Sue
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SueinWA
Posts: 313
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November 11, 2008, 07:16:31 PM |
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Leah, the bags themselves form a dome, a very sturdy type of structure. They are even stable in earthquakes, tested by the government in California.
Each layer of sandbags is moved inward a bit as you work your way around the circle. The barbed wire keeps each layer from slipping. You never move any layer so far inward that it tips.
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Actually, I just found a .pdf file that shows how it is done. They are using a tubular type of sandbag, but the regular simple rectangular bags work every bit as well, and are probably easier to fill.
http://www.calearth.org/Emerg_files/KhaliliEmergShltr.pdf
And more info at Back to How to Live Well on Very, Very Little at http://www.jmooneyham.com/shelp.html
Here is another type of sandbag shelter, but it takes more materials: http://www.earthbagbuilding.com/emergency/emergency.htm
Sue
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SueinWA
Posts: 313
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November 12, 2008, 12:49:20 PM |
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I think the answer lies in the circle. All the layers are leaning against each other.
Like if you just leaned over, you would fall over. But if you had six or eight people in a circle, all leaning forward and against each other, no one should fall over.
Apparently, you have to frame the door with wood or something rigid to maintain the support of the circle.
I am dying to try this! All I need is some money so I can pay some local teenage boys to do the heavy labor for me.
Oh, I just googled "dome strength" and the first thing up was an article at Wikipedia: "A dome can be thought of as an arch which has been rotated around its vertical axis. As such, domes have a great deal of structural strength. A small dome can be constructed of ordinary masonry, held together by friction and compressive forces ... A dome can sit directly on a circular base, however, this is not possible if the base is square."
It said the first dome was built in Rome in 64 A.D.
Sue
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SueinWA
Posts: 313
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November 13, 2008, 07:01:43 PM |
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Sand bags used to be made of burlap, so I don't see why not.
The modern bags are basically crap, IMHO. Well, IMO.
As long as you didn't take all summer to build it, and got it protected from sunlight UV, either should work.
Here's a site that sells all kinds of sandbags, and some are still burlap. http://www.daybag.com/industrial/sand_bags.html
I was wondering if you could support it properly with 2x4s, if you could make a sandbag greenhouse?
Sue
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