A earthship house is made up of rammed earth and tires. The tires are stacked (staggered) like bricks. Each tire has earth pounded into them until firmly packed. Once the tires are packed, they are very difficult to move and form quite a dense wall. The walls are load bearing and provide thermal mass which is an important attribute to any energy efficient house. Thermal mass stores heat and releases the heat slowly. This keeps indoor temperature constant while outside temperatures fluctuate. Once the walls are in place, the walls are quite often plastered over and appear very similar to an adobe style house.
Michael Reynolds a Southwestern US architect is credited with building the first earthship. His wife coined the phrase because the house was self-sustaining, requiring no outside source of water nor electricity. The house just kind of sailed around, hence the name earthship. The house was built out of discarded materials such as automobile tires and aluminum cans and finished with natural adobe.
What are the advantages of building an earthship?
Energy Efficiency - Earthships provide a large amount of thermal mass. This helps keep the house cool in the summer and warm in the winter. Most homes of this type have been built in the southwestern part of the United States although I did visit a house under construction in Bancroft, Ontario. I don't recall if the owners were going to insulate the outside at all, but it may not be a bad idea for northern climates.
Self-Sustainability - The homes are designed to take advantage of natural resources. The homes are typically built in rectangular form and oriented to take advantage of passive solar radiation. Rainwater is also stored in cisterns and gray water is recycled.
"Buildability" - Earthships can be owner built. There is obviously, quite a bit of labor involved but if time is not a factor, a house of this type could be built with just a couple of workers. Basic carpentry, plumbing and electric skills are required.
Easy Availability - Not only are tires easy to get, some places will pay you to take them away! There are plenty of tires, bottles and aluminum cans around.
What are the disadvantages of building an earthship?
- Resellability - With any other alternative house building types, you might have a problem reselling a house that is "different" from the norm. In most cases, the occupants who build alternative homes are usually building them for a lifetime, but if plans change and you need to sell, it may take longer to find a buyer.
Building Permits - As with all alternative building methods, you might run into some problems with local building codes. The walls are the biggest hurdle. The rest of the house is built using conventional building methods, but getting approval for the rammed tires might be a problem.
Financing - Earthships are a very new concept in building design. Fannie Mae, the nations largest supplier of home loans are exploring environmental loans that might include earthships sometime in the future.