Foundation and Design
An Earthship home is typically made from earth-rammed tires. These are used to construct the exterior walls of the entire structure except for the south-facing wall (in the Northern Hemisphere). The south wall is primarily large glass panels that are used for passive solar heating. A single earth-rammed tire can weigh upwards of 300 lbs., and therefore it is more efficient to construct them on site than to have to move them.
The process for creating the foundation wall is extremely labor intensive and requires at least two individuals. The first person digs the dirt, shoveling it into the empty tire, and the second individual pounds the dirt into the sides of the tire (this is the ramming). The tire is turned throughout the fill process to ensure that the fill is loaded evenly.
In early versions of the Earthship these tires were simply covered with adobe or natural plastering. The insulation value was thus limited to the two and a half feet of dirt and the thin insulating rubber of the tire (an R value of about 5). This limited the placement of Earthships to areas that didn’t experience extremely cold temperatures. Today there are various insulation materials that are used directly over the exterior of the tire before the finish is applied. This has allowed Earthships to be built as far north as Ontario, Canada.
Interior walls (and often casing walls for the tire structure) are created by stacking aluminum cans and mortaring them into place with cement. These walls are light and strong and can be designed in both straight lines and curves. Wire conduits can be built into the walls during construction to accommodate electrical needs and additional outlets can be inserted after construction with a simple wall punch. The thin layer of concrete and aluminum will open quickly and can be reinforced after the new wiring is installed.
Standard Earthships are built with the signature “U" shaped design. In addition to the passive solar design of the southern wall most Earthships have active solar and wind collectors and use other sustainable methods including rain collectors and biological grey water filtration.