Friday, February 29, 2008

Earth Construction Housing

Which building material ...

1. Absorbs and desorbs humidity faster, and to a higher extent, than any other?

2. Produces hardly any environmental pollution and can be recycled any number of times?

3. Balances indoor climate and moisture thus creating an extremely healthy environment in which to live?

The answer is EARTH.

In nearly all hot-dry and moderate climates of the world earth has been the predominant building material. Earth construction techniques have been known for more than nine thousand years and, even today, one-third of mankind lives in earth houses.

ADOBEOne example of effective, time-tested earth construction in the Americas is ADOBE

Adobe is a term widely used in the southwestern United States and Spanish speaking countries. Although the word is often used to describe an architectural style, adobe is actually a building material which uses bricks made of tightly compacted earth, clay and straw.

Construction methods and the composition of the adobe will vary according to climate and local customs. Sometimes an asphalt emulsion is added to help waterproof the adobe bricks. A mixture of Portland cement and lime may also be added, but these materials will add to the cost. In parts of Latin America, fermented cactus juice is used for waterproofing.

Want more details? Here's a inside view of an adobe house: RIM JOURNAL: House made of mud
RAMMED EARTHRaw earth is commonly acknowledged as the world's most widely used building material. Throughout recorded history artisans and village builders have used it to create durable housing. Today, earth building is in resurgence, but modern applications demand higher standards and greater care in construction than in the past. Stanford-educated inventor, author, teacher, and builder David Easton is the preeminent advocate for building with earth. Rammed Earth Works has developed important new technologies for building with natural earth. From award winning homes and wineries in California to community projects in developing countries, David Easton and Rammed Earth Works have proven how functional, appropriate, and attractive earth structures can be.

ADDITIONAL EARTH TECHNIQUESThe Green Homebuilding website provides good overview of a wide variety of earth-building techniques including the following:

Adobe:
Adobe is one of the oldest building materials in use. It is basically just dirt that has been moistened with water, sometimes with chopped straw or other fibers added for strength, and then allowed to dry in the desired shape.

Cob:
Cob is a very old method of building with earth and straw or other fibers. It is quite similar to adobe in that the basic mix of clay and sand is the same, but it usually has a higher percentage of long straw fibers mixed in.

Rammed Earth:
Ramming earth to create walls is at least as old as the Great Wall of China. It is really quite similar to adobe and cob techniques, in that the soil is mostly clay and sand. The difference is that the material is compressed or tamped into place.

Cast Earth:
Instead of making individual adobe blocks for building, or intensively ramming earth into forms little by little, you just pour the plastic earthen material into a form and have it set up very quickly.

Earthbag:
Building with earthbags (sometimes called sandbags) is both old and new. Sandbags have long been used, particularly by the military for creating strong, protective barriers, or for flood control. The same reasons that make them useful for building homes.

Strawbale:
There are two major categories of building with strawbales: load-bearing and non-load bearing. A post and beam framework that supports the basic structure of the building, with the bales of straw used as infill, is the most common non-load bearing approach.

Cordwood:
Cordwood construction utilizes short, round pieces of wood, similar to what would normally be considered firewood. Recent experiments with the use of cob instead of cement mortar to join the logs have been encouraging and this method may provide a somewhat more ecological approach to cordwood building.

Bamboo:
Bamboo is one of the most amazingly versatile and sustainable building materials available. One tricky aspect to the use of bamboo is in the joinery; since its strength comes from its integral structure, it cannot be joined with many of the traditional techniques used with wood.

Earthship:
The basic earthship design incorporates substantially bermed, passive solar architecture. The primary retaining walls are constructed with used tires, filled with earth and stacked up like bricks.

Papercrete: Papercrete is a fairly new ingredient in the natural building world. It is basically re-pulped paper fiber with portland cement or clay and/or other dirt added. Papercrete has been used as a plaster over straw bales, and it has worked out well.

Lightweight Concrete:
Lightweight concrete may be made by using lightweight aggregates, or by the use of foaming agents, such as aluminum powder, which generates gas while the concrete is still plastic. Natural lightweight aggregates include pumice, scoria, volcanic cinders, tuff, and diatomite.

Rock:
Building with rock dates back to the beginning of human history. Many cultures have left durable evidence of their fine craftsmanship with stone masonry.

PSP:
PSP stands for Post/Shoring/Polyethylene. The framework of the building is created with posts that are preserved in various ways and planted in the earth. These posts serve to support both the walls and the ceiling. The space between the posts is planked with used dimensional lumber, such as from wood pallets.

Hybrids:
In a sense, virtually all buildings are hybrids of one sort or another. Most modern buildings employ a wide range of materials, some "natural" some not. Some books that tell us more about building with this earth -- and people -- friendly building material:

Earth Construction Handbook:
The Building Material Earth in Modern Architecture by Gernot Minke
Buildings of Earth and Straw: Structural Design for Rammed Earth and Straw Bale Architecture by Bruce King

The Natural Plaster Book : Earth, Lime, and Gypsum Plasters for Natural Homes (Natural Building Series) by Cedar Rose Guelberth
Earthbag Building : The Tools, Tricks and Techniques (Natural Building Series) by Kaki Hunter
Planting Green Roofs and Living Walls by Nigel Dunnett

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