Cob is an ancient building technology being rediscovered for today’s green home. A gob is a clump of dirt and fiber that can be tossed from builder to builder on a cob work site. If throwing mud isn’t enough, try squishing it between your toes. Cob is traditionally made by mixing sand, clay, straw, and water with bare feet in a labor-intensive yet rewarding process for the do-it-yourselfer.
Building with cob (also called earthen building or natural building) is easy to learn, requires few manufactured resources, and no power tools. Cob walls are very forgiving, and the material is nontoxic, so kids can help with the project.
Because cob homes are hand-sculpted, they lend themselves to unusual shapes and curves. They are a good fit for passive solar design because their one to two foot walls provide impressive thermal mass that keeps the interior temperature stable.
Pipes and wires are laid directly in the wall, and there is no need for vapor barriers, sheetrock, or painting. Different mixtures of the same basic cob materials can produce plasters, floors, and interior structures like sleeping platforms.
Cob builders are typically aware of the benefits of building with local and natural materials. They often incorporate recycled and locally salvaged materials into dwellings that are both beautiful and affordable. Check out these cob homes handbuilt by MudGirls Natural Building Collective.
Imagine a self-sustaining dwelling that seems to have a life of its own—sheltering its inhabitants, providing food, supplying energy needs, and transforming waste. Are you in love yet? An Earthship is much more than a home; it’s an integration of harmonious systems akin to those in the human body.
Made largely of natural and recycled materials, Earthships have been more than forty years in the making. According to their creator Michael Reynolds, they can be built in any climate.
The need for heating and cooling in an Earthship is drastically reduced (or even eliminated) by the earth-bermed, passive solar design. The north side of a traditional earthship is constructed of stacked earth-filled tires, which are then earth-bermed. This significant amount of thermal mass keeps the interior temperature relatively stable. The tires are stacked in U shapes, each forming a room. Interior walls can also be constructed out of recycled material—cans in cement. The front of an Earthship is comprised of greenhouse windows with planters immediately inside. Planters serve a triple purpose—their vegetation cleanses the air; they provide growing space for food; and they serve as a greywater treatment system.
An Earthship’s roof is designed to collect water which is then channeled to a cistern. Once filtered, it is used four times:
For regular household use, excluding the toilet.
Passes through the interior botanical cells (planters).
Flushes the toilet.
Passes through to exterior botanical cells (outside plantings).
The exterior botanical cells are contained and work in concert with a conventional septic tank to satisfy many code requirements.
Part of the appeal of Earthships is that they can be owner-built. Although the process of filling and stacking tires is undeniably labor-intensive, it is relatively straightforward and does not require years of experience.
As with any basic housing design, an Earthship can be as sustainable as ingenuity and budget allow. Some homeowners are connected to the grid and have traditional drywall instead of can walls, while others stay more faithful to the original design.
This enthusiastic overview barely scratches the surface of all things Earthship. Ready to get your hands dirty? To learn more, visit http://www.earthship.net.
My grand-dad used to say “pick your poison.” He knew that nothing is perfect. There are good things and not so good things about every choice. When sustainability is your primary goal, you make decisions with a different set of parameters. You might be willing to put forth a little more time and effort knowing that the end result will benefit not only you, but the environment. But before you begin any big project, you better sit down with a paper and pencil and make the old “T” chart. I started one for you. Behold, some pros and cons of earthen plaster.
Pro
Low Environmental Impact
Energy intensive
Adds thermal mass for both passive and active solar heating
Relatively inexpensive
Easily patched and repaired
Adds a warm, natural feeling to your dwelling
Has great breathability
Provides a protective shell for your straw bale home
Lots of warm, rich colors
Variations in texture
Allows for artistic expression
Con
Can get saturated by rain and constant wetness
Can mold (grows on the organic matter in your plaster, but there are techniques to minimize or stop this)
Labor intensive
Doesn’t meet building codes in some localities
Can crack and “dust” if composition and consistency of earthen plaster is incorrect
Requires multiple coats
Sensitive to temperature and weather when applying
Is pretty messy!
I think the pro list is longer than the con. So if we follow “T” chart rules, this project is a go. Earthen plaster has been used for centuries. Earthen plaster dwellings have stood the test of time; you can find these dwellings literally scattered around the world. Why not add your home to the list?
Looking for “recipes” for earthen plaster? You can find several in my last post, Earthen Plaster Recipes.
We’ve heard it since our childhood. If you want a strong house (one that can’t be blown down!) you have to build with brick. There are plenty of folks that are proving that old tale wrong. The majority of these straw homes are being built in the west and southwest United States, Australia and New Zealand; places with a somewhat more dry and temperate climates. There is a registry of straw bale houses around the world—kind of interesting.
I have seen a straw home built in one of the harshest climates in the continental U.S.–Driggs, Idaho. Some years ago, I watched with great interest (and much skepticism) as this dwelling went up a mile or so from my parent’s home. Among the old farmers in the area, the house was the butt of more than a few jokes. Well, years later, it is still standing and functioning well and the farmers are getting used to the idea. Besides, it’s a new source to sell all that straw that the farmers’ grain fields generate.
Speaking of farmers, it was pioneer farmers who built straw and grass homes on the prairies of the Nebraska and Oklahoma over a century ago. No trees? No timber? No problem. Straw and grass were readily available, could be stacked like bricks, didn’t require elaborate tools, and could be constructed in a shorter period of time. The homes were well insulated, had great “breathability,” and believe it or not, were quite fire resistant. They created homes that were inexpensive, functional, and pleasant places to live in. Obviously, these are qualities that budget and environmentally conscious people are looking for today. History does need to repeat itself.
There is a plethora of websites, companies, and individuals who are eager to share their knowledge on the techniques of building a straw house. The science of straw house building and my attitude about the whole thing has come a long way since those days of me and the Idaho farmers standing around laughing and smirking at the neighbors. It is past time we all got serious about it.
Cob is an ancient building technology being rediscovered for today’s green home. A gob is a clump of dirt and fiber that can be tossed from builder to builder on a cob work site. If throwing mud isn’t enough, try squishing it between your toes. Cob is traditionally made by mixing sand, clay, straw, and water with bare feet in a labor-intensive yet rewarding process for the do-it-yourselfer.
We’ve heard it since our childhood. If you want a strong house (one that can’t be blown down!) you have to build with brick. There are plenty of folks that are proving that old tale wrong. The majority of these straw homes are being built in the west and southwest United States, Australia and New Zealand; places with a somewhat more dry and temperate climates. There is a 
