Homestead Green Building: Earthbags

So I was planning on writing about a different type of building this week as kind of a continuation of sorts from last week.  However, I live in Florida, and we just experienced Hurricane Matthew.  I had a very interesting conversation with a friend of mine, and we were discussing the devastation that happened in Haiti from this storm.  That conversation brought this building style to the forefront of my mind.  Let me tell you why.  My heart breaks for the people down there.  In fact, it breaks for any and everyone who lost all or part of their homes.  This particular building style is something quite special.  Earthbag buildings have been said to be hurricane-proof, earthquake-proof, and even bullet-proof.  There were a number of earthbag homes built in Haiti after the earthquake there not too long ago.  And in the aftermath of the large earthquake in Nepal, those buildings that had been built with earthbags were found to still be standing intact, while traditional-built buildings had completely collapsed.  Also, they are much less expensive to build than standard housing.  The only real cost is that of the bags and barbed wire.  And those can be acquired inexpensively, or even through barter in some cases.  These homes are ideal for areas prone to these kinds of natural events.

So what is earthbag building?  Well, it's pretty much exactly what it sounds like.  Earthbags, also referred to as sandbags (yes, the same kind used for protection against flooding), are filled with natural materials, and used to construct the building.  The bags can be filled with pretty much any natural substance, readily found on the property.  What you fill them with can determine their ability, if you will.  When filled with gravel, they can be used as a foundation layer to keep moisture away from your structure.  When filled with pumice, vermiculite, or something similar, they can act as a great insulating wall.  And when filled with soil, they make a great thermal mass.  See here for more information on that.  When the soil is moistened before being put in the bag, it can be referred to as "superadobe", a term that is credited to Nader Khalili at the California Institute of Earth Architecture.  Learn more about him and superadobe here.  This technique is also generally used with longer, earthbag tubes.  It can, however, be used with smaller bags, as well.  As far as which type of bag you choose to use in your structure, there are a lot of people with a lot of opinions.  The simplest answer is use what you are comfortable with.  Longer tubes may be difficult for only one or two people to handle, whereas smaller, individual bags can be done by one person.  Tubes are generally recommended when creating dome like structures.

To build an earthbag structure, it's really as simple as laying a row of bags, tamping them down, lay barbed wire, which holds the bags together, then lay the next row, and so on.  There may be some extra engineering involved to help brace the walls if you are planning on building underground, earth-sheltered or earth bermed.  But they are very suitable to such building designs.  These buildings are also versatile in that they can be rectangular, as with a traditional home, or circular, like a roundhouse.  Also, remember to include any framework for windows and doors right into the walls as you build them.  For the most part, the bags are all you need, with the barbed wire.  That can change with some factors.  If you are planning underground, especially completely underground, you may want to include a good wood or steel framework within the walls.  That may also be warranted if you want a green roof or have the possibility of heavy snow loads.  Also consider the shape of your roof.  Traditional roofs are a good design for green roofs, whereas domes can work great in just about any other situation.  And as for electrical and plumbing, they can be built straight into the walls, just as with cob.

To finish, it's a simple matter of choosing what kind of plaster you want to use, both on the interior and exterior.  Some people opt for traditional plaster, some use a cement plaster, while others use cob.  Of course, you don't have to use the same materials on both.  It's all up to you.  Again, though, remember that you may also need to consider weather/water-proofing.

The next question will most likely be how to determine how many earthbags you will need.  The answer will vary depending on the size of bags you wind up getting.  There are a number of different sizes available.  But to get a basic idea on determining how many, check here and here.  Once you determine how many you will need, there are a number of places to get them.  Sometimes, you can find them on eBay for a decent deal.  Sometimes, you may be fortunate enough to find them on Craigslist or even for free on sites like freecycle.org.  If you cannot find them there, you can always purchase them.  On occasion, some home improvement stores may carry them.  At the end of this post, you will find a short list of a few companies which sell these bags online.

This is a great green building technique that can be learned quickly and easily, and has the advantage of being easily built by either a large group, a few people, or even a single individual.  It is economical, environmentally friendly, and inexpensive.  It is versatile enough to be worked into just about any other building design, or as a stand alone structure.  There are many many benefits to building an earthbag home.  It is well worth the time to research it, truly consider it, and even find a workshop, if at all possible.  For more general information on earthbag building, here and here are good places to start.  And never forget to search youtube.  There are tons of tutorials there.  Happy researching!

Bag suppliers:

http://bagsupplies.ca/

https://www.onlinefabricstore.net/18-x-30-polypropylene-bag-.htm?gclid=CNyDiYSDqc0CFQgaaQodmbwIgA

http://www.chkbag.com/

http://www.earthbaghome.com/node/2

http://www.allinsafety.com/sandbags.aspx