6. Rammed Earth

For many people, wood is neither affordable nor available, so resourceful builders use what they have: the ground beneath their feet. To build a rammed earth home, a mixture of soils is packed down into a temporary wall form that shapes the mixture. The form is usually wooden, and it must be strong enough to withstand the compression of the ramming. Ramming can either be done by hand or by machine, and once it's completed, the forms can be removed, leaving an earthen wall about 18 inches to 24 inches (46 cm to 61 cm) thick.

Rammed earth walls require a cross-grade of soils, but too much clay will cause the walls to crack. Walls can be plastered with stucco or left bare; bare walls usually are internally stabilized with a small percentage of cement. When properly constructed, rammed earth walls are extremely durable, holding up in bad weather, as parts of the Great Wall of China can attest. They also provide energy savings because of their thermal mass.

If you prefer your earth neatly bagged rather than rammed, read on.