How to Build an Earth or Cob House for Less than $10,000

By Miranda Moore

Have you ever considered the affordability of environmentally friendly options like building a cob house?

Recently, there has been a vast increase in the demand for environmentally friendly options. Stores now give the option to ditch the standard paper and plastic shopping bags to opt for recyclable bags. Cleaning products have also tried to make an environmental statement by removing some of the harsh chemicals in their products in favor for more natural ingredients.

But here’s one that many may not yet know about—people may soon have the option to have an environmentally-friendly home. These eco-friendly styles of dwelling are known as earth and cob houses.

What are Earth Houses? Architecture and Cost

Earth houses, sometimes known as “earth berm” or “earth sheltered homes,” are an architectural style characterized by the use of natural terrain to help form the walls of the house. An earth home is usually set partially into the ground and covered with thin growth. Most modern earth houses are built with concrete walls and insulation.

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This earth house was designed by Swiss architect Peter Vetsch in Switzerland. Credit: Peter Vetsch

An earth house stays true to its name just by its concept. Unlike traditional, residential homes built on the ground, the aim of building one of these houses is not to live under or in the ground, but with it. These homes give new meaning to the term “tree huggers.”

According to the How Stuff Works website, constructing earth homes is similar to “building sandcastles without the tricky step of flipping the bucket.” Instead, the form of the home is usually made of a plywood structure that provides the outline of a wall. A mix of soils—usually made of sand, cement, and gravel—is rammed into the walls, which can be done by hand or machine. When everything is packed tightly, the forms are removed, and what is left is a solid, stable wall. Builders repeat this process until the entire house is built.

But how much does an earth house cost? According to the Green Building Elements website, a couple with yearly earnings of $10,000 went ahead and built an earth house for $5,000. But the cost would more than likely vary based on a person’s income, the materials used, and whether or not they used hired laborers. The couple built their home by hand.

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This is an earth house that was built by hand for $5,000. Credit: greenbuildingelements.com

An earth house that was constructed in Cerrillos, N.M., in 2002 is on the market for $749,000, according to the home’s listing website. The home sits on 120 acres and the home area is 4,000 square feet. An adjacent guest home is 900 square feet. The home is solar and wind powered, and was built by the homeowners.

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This is the interior room of earth home that is for sale in New Mexico. Credit: greenhomesforsale.com

Advantages and Disadvantages of an Earth and Cob House

The advantages of an earth house are primarily ecological and security related. Homeowners can save quite a bit on their energy bills with an earth home. This perk lies within its natural insulation. The unique architecture cools the house down in the summer and keeps it warm in the winter.

A further advantage is the higher air humidity that is between 50 and 70 percent, which means there will not be overheated rooms in the winter. Furthermore, as earth houses are impermeable, they can be considered ideal for controlled air conditioning.

The differential construction of a cob house protects them against severe windstorms. They cannot be torn apart nor tipped over by strong winds. The lack of corners or exposed parts eliminates vulnerable surfaces which would otherwise suffer from storm damage. Earth houses also benefit from improved stability due to the more natural shape of arches.

Compared to conventional buildings, an earth or cob house will fit perfectly into their surroundings. The soil-covered roofs help incorporate the environment, protect the natural scenery, and contribute to the oxygen-nitrogen balance of the soil. The soil would otherwise be covered by the foundation of a traditional house, inhibiting nitrogen fixation and aeration of the soil.

Lacking more flammable building materials, such as wood, an earth house offers more than your average home when it comes to fire safety. Due to the mass of the earth between the living area of an earth house and the surface grade, an earth home offers significant protection from impact and blast damage, or fallout associated with a nuclear bomb.

With the advantages of earth homes, there are disadvantages. The specific architecture of earth homes usually leads to non-righted, round-shaped walls. This could cause problems with interior decorating, especially regarding furniture and large paintings. However, these problems can be considered during the conceptual design of the home.

Unless properly ventilated, these homes can have very high humidity levels. High humidity levels lends to mold and mildew growth.

Despite large windows, many earth homes have dark space in the areas opposite the windows. Basically, all the natural light coming from one side of the house creates a “tunnel effect.” This can be remedied by using artificial light sources.

Earth homes have an unorthodox design compared to traditional homes. Local building codes may have to be researched in order to avoid conflict.

What is a Cob House?

A cob house is environmentally friendly, and cob is a natural building material made of sand, clay, and straw. Just like earth houses, cob homes have also withstood the test of time and have been able to last for generations.

When it comes to its look, a cob house does share a similarity with earth houses. According to the Green Building Elements website, cob homes have a “curvy design, with rounded doorways and curved walls.”

How to Build a Cob House for Under $10,000.

Just like earth houses, builders of a cob house would need to find out about the territory’s building codes before they start construction. According to Brian Liloia of small-scale.net, a cob house can be built to the tune of $3,000. Even cob house plans can be found for cheap or free, just check out DreamGreenHomes.com.

Liloia estimates that his cob house construction took him nine months of working full time to complete with the help of friends and visitors from time to time. He stomped the cob that was used to construct the house, which was around 219 batches of cob. According to Liloia, one batch of cob is “nearly 30 gallons of material.”

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This is a cob house that cost $3,000 to build. Credit: Brian “Ziggy” Liloia

You can mix the materials of sand, clay, and straw by foot or machine. The mixture must be wet and, to make construction easier, form the mixture into loaf-shaped blobs. The wet materials are used to build thick, earth walls. According to housealive.org, the technique is similar to sculpting with modeling clay.

“There’s nothing quite like the experience of building your own home with little more than your hands,” Liloia wrote on his blog.

An advantage to building with cob is that it requires no forms—unlike earth houses. Walls can be formed in any desired shape from curves and niches to arch. This process also does not require cement or expensive tools. It is a “people friendly” way of building and is often constructed with a large amount of builders. Think of it as a giant art project that can be lived in.

Cob houses are also available for purchase. In Mayetta, Kan., there is a cob house for sale with an asking price of $205,000, according to the home’s listing website.

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This is a cob home for sale in Kansas. Credit: greenhomesforsale.com

Built in 2004, this cob house is entirely solar powered and is located on 20 acres of forest. Two ponds and a creek are on the property as well as native plant medicine such as raspberries, gooseberries and blackberries.

Advantages and Disadvantages: Natural Heating and Forces of Nature

Just like earth houses, cob houses keep the home cool in the summer and warm in the winter with its natural properties.

Unfortunately, cob houses are not protected from strong winds like earth homes do. A large roof overhang will protect from all but driving rains. Depending on climate conditions, some types of finish added to the cob may help.

Obviously both homes have their advantages and disadvantages. Of course, pros and cons come whether you plan to build a traditional or a nontraditional home. Now that we are in an age where “going green” and environmentally friendly alternatives are important, maybe these houses could be the next mainstay in construction. An earth or cob house sure could help lower that electric bill.

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