dirt bag structures

I'm guessing that these have really poor insulation. Anybody know?

Anybody tinkered with this kind of construction?

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.

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

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 ...

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

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.

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.

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.

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...

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

I never thought of of that for a hidy hole from tornados. I'm smack in the middle of tornado alley and it can get a bit stressful in the spring watching those things come at you on the radar! at the same time I love storm season its rather thrilling to go out and watch them move through.

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! 

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

If it was built right I bet it could survive most tornados and would be better than nothing. Probably not going to survive the really big ones they take the asphalt of the roads quite literally and you simply have to be underground if you want to make it out of those..

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

Getting hit with one of the big ones is highly unlikely but they will sand the asphalt of roads. I remember a bizarre picture I saw years ago of a playing card (as in deck of cards) that was stuck 1/2 in a brick wall after a tornado. It is reallystrange how few people have storm shelters here. I don't. Safe rooms have been a big hit after a major storm cut a wide path from OKC and up I44 for miles in ?'99?. they are steel closets that they bolt to your foundation.  A dirt bag structure would be a great relatively inexpensive option and a hell of alot better than nothing!

here is a pic of the road damage after one.

Tornadoes sound so scary to me that I wouldn't live there unless I had a hidey hole really close.

Sue

I have lived in this area all my life so I suppose I'm desensitized to the scaryness. there has only been one time when I was seriously scared. that was when I was living in a trailer alone on a large acreage and the radar was showing that a large tornado was likely on the ground just south of the river (as I was) and 1 mile west of me coming my way for what looked like a direct hit. I had my four dogs on leashes my parrot and cats in carriers (not the same one )and was standing on my front porch waiting to run into the deep creek bed that curved behind my house. It went about 1/2 mile south of me. whew.

I question whether gradually sloping the bags in would work without some sort of initial support like they use while building a brick or stone arch. does anyone have any first hand experience building one of these things and can tell us the logistics of creating the roof?

I hope to build an earthbag structure in a couple years if my other projects don't get in the way.  Not sure if it would be liveable or not.  Maybe would make an emergency doomsday structure I can hide in.

one would probably make a pretty good fallout shelter. especially if you covered it in rocks and lots of soil.

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

I get that its the same idea as building an arch with brick but.. the center peice is key in that situation. the structure is very stable after it is completeed and all the pressure can be placed on the center piece.



        W  after you get to about here... I can't see any amount of
    W    barbed wire keeping the weight of the top 3 from           
  w        tipping off the bottom.  unless your walls are nearly
W          vertical. try stacking old magazines this way and glue                them as you go. before too long your whole "wall" will fall over.
there is architecturaly more to the story I'm sure.

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

I can see if the door was framed it working. it would be a fun project. what are some ideas to use as the bags? I ...was thinking I can get burlap sacks pretty cheap, or would old feed bags work? I imagine once it is up and has the plaster on it that it wouldn't matter if the original bags deteriorated within the wall ...would it?

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

now thats an idea! the mass would help retain heat from the day and protect the plants. maintaining the circular form might be difficult whilst trying to manage solar gain and figure out a suitable greenhouse roof. but I'm sure it could be worked out.

I am bringing this topic up again after reading about the horrible fires in Australia.  Almost 200 people died, many burned, cars caught fire while the people were trying to escape.

But there were some people in the outback who had underground shelters that saved their lives.

Some people don't realize that earth-sheltered homes or survival bunkers take a long time to heat up, and if they're all or partly underground, the cooler soil temperatures will help to mitigate above-ground temperatures, even if they are extreme.

Bill Mollison said something like this is crucial to a homestead, esp if you only have one vehicle and the driver works in town or away from home.

Be sure to build an adobe-type brick dogleg wall in front of the entrance to cut down on the amount of radiant heat that the door is exposed to.  You just don't want to expose a door (metal or wood) to direct firestorm radiant heat.

Sue

A problem I have with thinking about making earthbag structure, is the potential of high radon levels.  I know the area I live in is considered to have high levels of it.  So surrounding myself with earth, and being partially submerged in this earth would possibly carry such risks of radon.  I know my parent's basement was tested and has unsafe levels as it is. 

So its like I could spend a sum of money on this earthbag structure, only to find out that I don't even want to spend any time in it.  I still plan on building one though.  I've been scouting areas to make a test one.  I think the first one would be like a poultry shed.  And I'll harvest small diameter logs and put them throughout the structure, so the birds can fly up to roost. 

Just some daydreaming I do in the winter


Triangle southside of hill.


Pretending I have two earthbag structures and area planted in trees


Trees shade the structures in summer.  And would have them painted in dark color I'm thinking, so winter they would absorb more heat. 

This is a good site for step by step of what an older guy did
http://www.autobestbuysweekly.com/Dome/

I was just googling 'dealing with radon' and found this site with basic info.

(excerpt)
"Dealing with radon in homes

Radon levels in indoor air can be lowered in a number of ways, from sealing cracks in floors and walls to increasing the ventilation rate of the building. The five principal ways of reducing the amount of radon accumulating in a house are:

    * Improving the ventilation of the house and avoiding the transport of radon from the basement into living rooms;
    * Increasing under-floor ventilation;
    * Installing a radon sump system in the basement;
    * Sealing floors and walls; and
    * Installing a positive pressurization or positive supply ventilation system.

Radon safety should be considered when new houses are built, particularly in high radon areas. In Europe and the United States, the inclusion of protective measures in new buildings has become routine for some builders and - in some countries - has become a mandatory procedure. Passive systems of mitigation have been shown to be capable of reducing indoor radon levels by up to 50%. When radon ventilation fans are added (active system) radon levels can be reduced further. "

I don't know if this is possible with this construction method, but a small structure might be useful temporarily as a tornado shelter or weather shelter after a disaster, rather than a full-time living structure.

Sue

From what I have been reading regarding earth structures, you need to have at least 12 inches of earth in order to take advantage of the thermal qualities of it.
The bags most commonly used for this are about 22 inches wide when filled, which would allow the user to take advantage of the thermal qualities of the earthen materials in them.  It seems that the bags are easier to use, and the long tubes more difficult.
Most of what I have read regarding the "insulative" qualities of earth stress that you have to look at the thermal qualities of the earthen material, and not the insulation value.
The thermal qualities are often referred to as the "flywheel effect" of the earth.  IE it absorbs heat during the day and reflects it back out during the cold and vice versa, so when considering an earth structure the depth of the material is the biggest concern.
I read an article about cob houses (similar to earth bag) in England that have been in constant use for three to five hundred years and were quite comfortable to live in.  Since England is pretty cold and rainy it appears that a home built out of earth most places would be a good investment. 

our recent earlier than normal heatwave has encouraged me to give this some more thought. highs all week over 100* and I just wonder what would we do if we didn't have AC? live in the pond  ? what about food?  temps like that coupled with the humidity are dangerous and an earthbag or underground shelter would be very advantageous.

i just love the name of the thread..i have known a lot of dirt bags I would like to build a house out of.

Most of the builders I used to work for/with were dirtbags. I actually quit that profession after I saw a guy that was high as a kite shoot himself twice in the same hand with a nailgun.

about a month ago, I was trying to build a structure out of earthbags.  Didn't turn out how I had hoped, but overall a success considering its first thing I ever tried to build.  Haven't worked on it for a month though because was raining all the time and can't work with mud. 
Its about mile from where I live, so its a good emergency hideout because seems like I'm over there and get caught in storms. 

LoonyK wrote:
about a month ago, I was trying to build a structure out of earthbags.   Didn't turn out how I had hoped, but overall a success considering its first thing I ever tried to build.  Haven't worked on it for a month though because was raining all the time and can't work with mud. 
Its about mile from where I live, so its a good emergency hideout because seems like I'm over there and get caught in storms. 

Can you upload some pics?

cleared earthbag site

made outline

digging some more

done digging, wished dug deeper so wouldn't have to berm so much







now you see it

now you don't

wow
great pics

What did you do for the roof?