Natural materials have been used for thousands of years to construct dwellings. Soil, is perhaps the oldest and most widely used building material in the world.

Rammed Earth

People have been building structures using rammed earth for centuries. Parts of the Great Wall of China were built using the material. Rammed earth is formed by mixing clay and sand with a little cement. The resulting mixture is compacted to about 25 percent of its original volume and laid out to dry. For added protection against moisture, finished walls can then be stuccoed, plastered, painted or simply left as is and sealed. Rammed earth walls are built thick, like those of adobe, and consequently act as great insulation. The high thermal mass moderates a building’s temperature fluctuations, keeping houses at a relatively comfortable constant temperature. The materials needed to create rammed earth are inexpensive and non-toxic, but the process of tamping, by which the mixture is successively compacted into smaller, stronger earthen blocks, is time consuming and labor intensive. Due to this laborious process, construction using rammed earth is typically more expensive than traditional stick-built homes.

PISE

A new earthen building material called pneumatically impacted stabilized earth or PISE, was recently developed by builder David Easton. It looks and performs similar to adobe and rammed earth structures, but it is stronger and more resistant to moisture than adobe and takes considerably less time to build than rammed earth. Houses using this construction are built a whole wall at a time. Earth, cement, and water are mixed together and sprayed through a large industrial hose at a temporary structural form that serves as a mold of sorts. When the mixture has dried, the form is removed and is used again to mold another side of the house. Experienced building crews can construct as much as 1000 square feet of 18 inch-thick walls per day. PISE’s use of temporary structural forms allows for the electricity and plumbing to be in place before the wall is cast. Rebar, or reinforcing steel, can also be installed prior to PISE being sprayed, making it possible to build multiple stories. The technology is rather new and therefore unavailable in most parts of the country.

Straw Bale

Constructing a house using straw bale technique enables you to build in an environmentally-friendly, sustainable, and rather inexpensive manner. Every year more than 200 million tons of unwanted straw- which is the leftover stems of harvested grains like rice and wheat- is left in fields or burned after the harvest. The most common construction systems using straw bales are post and beam and structural bale. In the post and beam systems a support framework of timbers buttresses the weight of the roof. Straw bales are then stacked between the load-bearing posts for insulation.

No timber is used in the structural system. Straw bales are stacked one on top of the other like bricks and compose the entire structure of the house. Both systems place straw bales on top of the foundation to protect against water seepage. Houses are outfitted with electricity and plumbing and then the external walls are stuccoed, while the internal walls are plastered to prevent damage from moisture. Straw bale houses typically employ a wood frame roof.

The high insulating properties of the straw translate into lower electricity bills. Straw bale houses are inexpensive to build and they require little maintenance. The walls are also extremely fire-resistant, waterproof and highly pest-resistant. The construction of these houses is quite simple- a group or community could erect a house in a single day.