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Natural Building Techniques


Introduction
Adobe
Bamboo
Cob
Compressed Earth Blocks
Earthbags
Earthen Floors
Earthships
Hybrid Structures
Light Straw-Clay (Leichtlehm)
Hemp and other Fibers
Living Roofs
Natural Plasters and Finishes
Paper Blocks
Rammed Earth
Recycled Building Materials
Straw Bale Construction
Thatch
Wattle and Daub
Wood
Conclusion
Bibliography

Adobe Bricks: Sun-Dried Mud

Bricks made out of sun-dried mud are called adobes, and they are sealed together with mud mortar to build structures with thick walls. The use of adobe bricks dates back to the natural building techniques used in the southwestern United States, South America, and the Middle East.

It is interesting to observe the use of these building techniques in our modern world, because it is view differently depending on the area of the world. For example, in the southwestern United States, the rich population often uses adobe for their building material... while the "South" areas commonly use these materials in the poor areas. This building technique requires a lot of labor, and simple tools, so it is widely used in areas where there are many workers and not a lot of capital.

When adobe bricks are created, a combination of sand and clay is pressed or poured into forms, sometimes using manure or straw in the mixture as well. The bricks require a lot of time to dry, usually several days on each side to ensure they have dried completely. Typically, the buildings are started with a solid foundation of either concrete or stone, and then the adobe bricks are laid on top of the foundation.

Our modern world has changed the use of adobes in some areas, sometimes adding in concrete based mortar to help with durability. Sometimes, cement or asphalt compounds are added to the bricks to help with stabilization.
 
One drawback to using adobe is the fact that the durability needs to be protected from the elements. Often, wide eaves are built to protect the building from the rain. Sometimes, cement stucco is used to coat the adobe bricks, but it can result in problems because it is common for the stucco to crack which allows moisture to seep into the adobe bricks. This cracking and weakening of the building could potentially result in a weakened building, which could collapse without warning. 

Because of these potential problems, it is more common for builders to favor the use of other natural materials such as straw and mud plasters. Also, building codes in certain areas limit construction with adobe bricks because of the safety hazards, often limiting it to the southwest areas in the desert.


Bamboo Plants

Bamboo is a great source of fast growing, renewable building materials that can be used for many different purposes. These building techniques are more common in tropical areas, where bamboo freely grows.

North America does not commonly use bamboo in building, because it is difficult to import living plants, and builders are lacking in knowledge about traditional techniques that have been used in other parts of the world. But, it is becoming more widely known, especially because the prices of timber and other building materials have been increasing.

Even though bamboo is a form of grass, it is actually strong enough that it can be used to replace materials such as steel and wood. Some examples of the use of bamboo include building trusses, replacing rebar to strengthen concrete, for plumbing, or for decorative elements within a home.
 
The only danger to widespread use of bamboo lies in the fact that vast amounts of cropping may result in a negative impact to ecosystems in the tropical areas. If bamboo is exported, it is important to look at programs to promote sustainable growing periods for the ecosystems to flourish.

Cob: Straw and Moist Earth

A technique anciently known as "cob" is the process of using "cobs" to build monolithic walls with building materials such as straw and moist earth. Some of the benefits of cob is the fact that minimal building tools are required, and the techniques are easy enough that they can be implemented by both old and young people.

"Cobs" are actually small loaves of material, formed out of fibrous materials such as clay, sand, and straw. A stiff mud is created out of these materials, and formed into the building blocks. When the building is created, a concrete or stone foundation is laid, then the cobs are put together and mashed on top of the foundation, building a monolithic wall.

These building techniques create thick walls, sometimes up to six feet in width. Each layer needs to have time to solidify before the next layer is applied, and sharp tools can be used to shave off irregularities.

Cob techniques are particularly popular because of the fact that they offer strength, ease of building, thermal mass, and they can be easily integrated with other techniques. It is easy to create details such as windows and other decorative details in the structure.

In the United States, cob techniques are still in experimental phases, because procedures are still being investigated for code compliance. In England, cob is being reintroduced, because 500-year-old cob structures have been discovered in perfect condition. This technique is quite economical, but time consuming because of the labor-intensive requirements as well as the time that the walls take to cure.


Compressed Earth Blocks

Similar to adobe building techniques, compressed earth blocks are made with natural resources and compressed into building blocks. The main differences between these two natural building techniques are that compressed earth blocks tend to be more dense, they are not completely saturated with water, and the machinery used to create the blocks help to ensure uniformity in all of the building materials.

The cost of compressed earth blocks can greatly vary depending on how they are produced. Traditional methods involve a lot of human labor and they are fairly inexpensive. But, modern technology has allowed these blocks to be created by machinery, which can raise the price because of the fuel and equipment used during the production processes. These modern methods are more efficient though, thousands of bricks can be produced each day.

The uniformity of these bricks allow them to be tightly stacked, which means that little mortar is needed in the construction process. Also, construction is faster and the walls are straighter compared to the older methods that were used.

Earthbags (Filled With Soil)

Fabric sacks filled with soil are known as earthbags, and they are great building materials for constructing domes and walls. Originally, these soil-filled bags were used for water control during floods, or to build bunkers during war. But, in recent years, they have been used as a natural construction method.

Using earthbags for home construction is still a newer concept, but there are a lot of promising ideas around this technique because it is easy, fast, and forgiving. When buildings are constructed with earthbags, the soil is moistened before it is placed in the bag. Then, the bags are carefully placed onto a foundation, and a hand tamper is used to compress the bags together.

These bags can actually be very sturdy once they are set. In fact, if heavier mixtures are used within the bags, weaker bags are sufficient because the compressed soil is strong after it has set. If sandy soil is being used, then stronger bags should be used, such as polypropylene bags. If these bags are used for construction in an earthquake prone area, it is best to add barbed wire between the bags to prevent slipping in the case of an earthquake.

Sometimes earthbags are used as a foundation for other natural building techniques. For example, the earthbags may be a good foundation, and then bale, straw, or cob materials are used for the rest of the structure.

Earthen Floors

Earthen floors are created by pouring together earth mixtures to create floors, or tamping the earth to solidify the floor. This natural building technique starts with a substrate of sand, pumice, or gravel, which is topped with the earthen mixture which is poured down or tamped down over the gravel. Often, several layers are earthen floors are used to strengthen the floor. Sometimes, a sublayer may be added in using clay and straw, which is beneficial for insulation purposes.

Once the floors dry, it is common for cracks to appear, and those cracks are filled in with additional mud. In addition to the natural building materials, a hardening substance may be used such as glue, cement, or lime. Additionally, a finishing layer of turpentine or linseed oil may be used to seal the floor, and then was is used to protect the surface from damage.

There are many advantages to this natural building technique, although a few minor disadvantages include the fact that ongoing maintenance is needed and there is a likely risk of damage to the flooring. Additionally, it is a slow construction process because it takes time to allow the layers to completely dry.

The advantages of using this type of natural flooring are that the materials are often free and they can be locally sourced. Also, the floor is soft on the feet, and there are many aesthetic values to the appearance of the floors.

Earthships: Independent Solar Design Structures

Michael Reynolds developed "earthships," which are structures that use recycled materials, and they are independent running on solar power. These structures are not completely "natural" because they use some unnatural materials, but the conventional items that are used are created from recycled trash which would otherwise be polluting the planet.

Earthships are created on hillsides that face south. The hill is dug, and tires filled with soil are used to form walls and sides of the structure. The tires are stacked like bricks, and the gaps between the tires are filled with old cans and bottles for detail features in the walls. On the south side of the building, it is framed using wood, and metal is used on the roof which is designed to catch rain water. Other earth-friendly features include solar hot water, treatment for waste water, solar heating, and photovoltaic electrical systems.

Leichtlehm: Light Clay-Straw

The word "leichtlem" is a German word which means "light-loam," and this natural building technique incorporates the used of loose straw and clay. Forms are used, and the straw is coated in the clay and them rammed into those forms in order to create structures of timber frames.

Typically, the frame structure is filled with a thick mixture of straw and clay. Eventually, a lighter frame of wood is constructed on the outside to help anchor the clay-straw walls. For better insulation, the clay content can be decreased to focus more on the use of the straw.

There are variations of this building technique that use materials such as clay and wood chips, which are formed into bricks. Using the straw-clay technique, buildings can be built with a high level of accuracy and it looks very comparable to standard frame houses. The problem with this technique is the fact that it takes a long time because the straw-clay mixture needs to dry.

Fibers: Such as Hemp

Certain fibrous plants can be used as natural building materials, some of the most popular being hemp, sawgrass, and kenaf. Previously, hemp was used for many purposes, but recent drug laws have made it illegal to cultivate hemp. So, hemp that is non-psychoactive is not being investigated for it's use as oil, hurd, and fiber.

Various ways that hemp can be used include: adding it to material that is similar to concrete or creating fiberboards out of pressed hemp. Advantages of using hemp include facts such as: it is a renewable crop (annually), requires small amounts of chemical processing, can grow and thrive in low quality soil, and it produces higher amounts of usable fiber (four times more than wood, per acre). The main drawback to using hemp is that it can be expensive since it must be imported because of the misguided laws.

Natural Building Techniques and Children's Health

So, why does it matter if natural building materials are used for your home? Isn't it easier to just use the standard building materials that are typical in home construction? The truth is that there are many irritants, chemicals, and pollutants in the common building materials, and on-going exposure to these items can be potentially dangerous for the health of your children. Our modern world is taxing the bodies of people, both old and young, because there are so many environmental factors that are dangerous to our health.

Isn't home supposed to be a safe place, where your children can grow and thrive without dangerous substances? Using natural building materials can affect them both physically and emotionally... physically, because they are not constantly exposed to dangerous pollutants, and emotionally because the natural materials can provide children with a grounding sense of well-being, because they are near the natural elements of the earth.

Additionally, natural building techniques are important because of the fact that our world is quickly using up many of the resources that are available. Our current path of living is not sustainable, which means that our children's generation is going to have a very difficult time getting the commonly used resources such as wood. What are they going to do when so many of the forests throughout the world have been cut down?

As parents, we can do our part to make less of an impact on the environment by using natural building materials for our homes. These techniques provide a safe environment for our families, we use less resources, and we can be good examples to our children.


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