Homes made from earthen materials are affordable, comfortable, sustainable, nontoxic and enduring. Building homes from earthen materials has a long, illustrious past. For virtually all of history, our ancestors lived in shelter fashioned from locally available materials, especially earth. Today, approximately half the world's people still inhabit dwellings made with soils harvested from the Earth's crust.

Why Build With Earth?

For one. earthen homes are clean, comfortable and beautiful—even breathtaking. The thick. solid walls create a sense of comfort and security. Walls made of earth are not only strong, they are capable of resisting insects, earthquakes, hurricanes, tornadoes and fire. They have the very real potential to last hundreds of years. 

Earthen homes are appropriate for a variety of climates and are ideally suited for passive solar heating and cooling. If designed well, they stay warm in the winter and cool in the summer with little, if any need for auxiliary energy. Built largely from soil excavated on site, earthen homes require substantially less fossil fuel derived energy to build than the conventional wood-frame homes popping up by the millions.

Reduced energy consumption provides a wide range of environmental benefits, including reductions in greenhouse gas emissions. Earth homes require much less wood to build, helping ease pressure on the world's over-harvested forests. Materials are collected locally: No huge mines or clear-cut forests are required to supply building materials, and the blemish produced when extracting earth can generally be repaired quickly and easily with little environmental impact. A hole dug to extract clay-rich dirt for an adobe home, for instance, can be filled in, graded and replanted, or it can be left to fill with water, creating a pond for wildlife to drink from on hot summer days.

Earth homes can be quite economical, further adding to their appeal.

Adobe brick home-building is an ancient technique that originated in the Middle East and later spread to Europe. As the Spanish sought riches in the New World, they brought this method with them. Today it is still practiced in Mexico and to a lesser degree in other parts of North America.

Traditional builders use adobe blocks made from a mix of clay-rich soil, sand, straw and water. The mixture is poured into block forms and baked in the sun. A couple of weeks later, the bricks are ready for use.

Like conventional bricks, adobes are laid in a running bond-an overlapping pattern-then mortared in place with adobe mud. For added protection, adobe walls should be finished with an earthen or mud plaster.

Although traditional adobe block-making still reigns in poorer countries, many contemporary adobe builders in North America are substituting machine-made blocks—called pressed earth blocks—for sun-dried adobes.

Pressed earth blocks are stabilized with a little cement and cranked out in a fraction of the time of a traditional adobe brick. This process generates more uniform blocks and makes adobe home construction feasible in wetter climates. Despite these advantages, pressed earth blocks represent industrial production shunned by some in the natural building movement. Beehive Home Builders will not incorporate cement into any of its adobe bricks as conventional cement retains atmospheric radiation.

There are still many good reasons to continue this centuries-old adobe tradition, besides the general benefits of earthen building mentioned earlier.

Advantages of Adobe

• Adobe mud is a widely available, local resource.
• Construction is approved by most building departments.
• For owner-builders traditional adobe is inexpensive and a fairly low-skill job.
• Durable, fireproof and nontoxic.

• Building is time-consuming and labor intensive.
• If labor costs are high, adobe home construction can be quite expensive.
• Traditional adobe block construction requires adequate drying periods, and thus might not be suitable for wetter, colder climates.

Cob Homes

Cob is an Old English word meaning a lump or rounded mass. Cob homes are mud-walled buildings, made from rounded masses of clay-rich dirt stacked on foundations by hand, then kneaded and shaped to produce smooth surfaced walls.

Cob builder Becky Bee, author of The Cob Builder's Handbook, likens cob construction to "hand-sculpting a giant pot to live in." Unlike clay pots, though, the walls of cob rooms are thick 14 to 24 inches- strong and durable. When the cob mix dries, it takes on the hardness of sandstones.

Like adobe, cob consists of mud and straw. Mixed in pits, usually tromped by feet, the cob is then formed into small-loaves, which are deposited on the foundation, then massaged and shaped by hand.

Slowly but surely, a wall emerges with smooth, curved surfaces. Finished cob walls may be left unplastered or may be painted with a traditional lime wash to provide protection and beauty. In many homes cob is coated with an attractive protective layer of earthen or lime plaster

Advantages of Cob

• Wall building is fun, easy to learn and relatively inexpensive.
• Encourages artistic expression and lends itself to curved walls and other usually exciting features, such as niches
• Durable, fireproof and nontoxic.

Disadvantages of Cob

• In most of North America cob is a "new" building concept: obtaining approval may be difficult.
• Can be time-consuming.

Rammed Earth Homes

Rammed earth is one of the oldest of all natural building methods. Rooted in North Africa and the Middle East, it dates back to the time of the pharaohs. Today commercial builders in California, New Mexico, Arizona and Colorado are using this time-tested technique to construct modern homes.

Traditional rammed-earth construction relies on a mix of 70 percent sand and aggregate (small stone) and 30 percent clay. The clay acts as a binding agent.

In areas where moisture and earthquakes are a problem, rammed-earth builders often use a mix of sand and Portland cement, although the results lack the visual appeal of raw earth walls. Rammed-earth walls may be left as is, or plastered or stuccoed to provide an additional measure of protection.

Advantages of Rammed Earth

• Produces an extremely attractive and enduring structure.
• Suitable for many different architectural styles.
• Often cheaper to build than brick, stone and adobe structures.

Disadvantages of Rammed Earth

• Requires special skills and construction of forms; generally not suited for owner-builders.
• Costly, if labor costs are high.
• May be difficult to gain building department approval.

Earthbag Homes

Although humans have been using sandbags to build bunkers and to hold back rising flood waters for a very long time, building homes from bags of dirt is a relatively new concept in the field of natural building.

Earthbag walls are made from reject burlap or polypropylene bags (the kind bulk rice comes in). The bags are filled with slightly moistened clay-dirt or cement-stabilized dirt, then pinned shut, laid down on a foundation and tamped. When the soil dries, it hardens like rammed earth. Earthbags are set in a running bond, then covered with plaster. Earthbags are ideal for creating vaults or for building round structures with domed roofs.

• Easy to learn.
• Used to build domes, vaults, foundations and patio walls.

Disadvantages of Earthbag Construction

• Labor-intensive.
• New, and thus difficult to obtain approval from building authorities.

Climate Suitability

Earth homes are suitable in a wide range of climates, even some rather wet ones. Cob, for example, does extremely well in Oregon's soggy, rainy forests and Old England's wind-battered, rain-drenched coasts.

In all earth building systems, the key to success in wet climates is to prevent the mud from being eroded away by protecting walls from rain. A well-designed roof with a suitable overhang and other design features provide adequate protection. A protective coat of lime plaster is often applied for added durability.  

Most earth homes are concentrated in hot, dry climates and are suited for passive solar heating and cooling in such areas. Thick wall mass protects interiors from temperature extremes.