the Primary Building Block: Provides the major structure and performance of the earthship. These building blocks are arranged to form the main load-bearing walls of the building. This building block is an automobile tire rammed with packed earth. Another way to describe it is rammed earth encased in steel belted rubber.
Let’s take the primary building block of earthship biotecture through the outline of characteristics and requirements for the ideal building block for humanity on planet earth…
Indigenous: The rubber of the tire (sometimes steel belted) is indigenous all over the planet as a ‘natural resource’. Every city is a natural supplier of this item. It can be ‘harvested’ with absolutely no technical devices or energy other than two people to pick up and throw into a pickup truck. The tire is readily available without the energy and fuel/pollution impact of shipping building materials to every potential building site.
Able to be fashioned with little or no energy: The automobile tire can be used as found without any modification. The process of ramming them full of denselt packed earth is achieved with simple human labor and can be done with whatever type of earth is available on the building site. Common people of all shapes and sizes can easily learn to gather tires and pack them full of earth with simple hand tools and with the same type of human energy that they use while trying to tone up their bodies in the local spa. The impact of large scale uuse of this idea would result in depletion of the giant tire mountains that have become a serious problem in many cities. This building block is therefore achievfed with little or no manufactured additional energy.
Thermal Mass: There are few materials, if any that would provide better, more dense mass for storing temperature than rammed earth. The rubber tire casings provide a natural form for humanly manageable production of thermal mass building blocks with little more than human energy. There are very few materials that would provide the structural bearing capacities and homogenous qualities of an earth rammed tire wall. The diameter of the tires (2′-4″) sets the thickness for the walls at 2′-8″ with plaster, finish. This amount of dense mass surrounding every room of an earthship provides a thermal battery like no other in construction history.
Durability: the durability of tires filled with earth can not be surpassed. A buried tire (which is in effect what we have in a tire wall) will virtually last forever. The only thinf that deteriorates rubber tires is sunlight or fire. Since they are filled with earth and ultimately covered with earth, they never see sunlight when built into an earthship. Tires only burn when surrounded by air. when they are filled and coated with earth, trying to get them to burn would be like trying to light a phonebook on fire as compared to a wad of paper. The very quality of tires that makes them a problem to society (the fact that they wont go away) makes them an ideal durable building material for earthships. Earth and tires by virtue of their very nature will last forever.
Resilient: Whereas a rubber tire/rammed earth wall is amazingly strong, it is obviously not brittle. It can vibrate or move without fracture of failure. Since these walls are so wide and the loading on them is widely distributed, the entire structure would have the potential of absorbing and moving with considerable horizontal shock from an earthquake. There is probably no other matierla available at any price that has the reliance that earth rammed tires would have. They do provide a dense, rubbery, flexible wall.
Low specific skill requirements: Thousands of people all over the world have learned how to ‘pound tires’ Within one or two hours the average human can be an expert. It requires physical energy more than brite strength. A team of two people, one shoveling and one pounding, can pound about four tires an hour. The shoveling job is easiest while the pounding requires a little more strength and energy. The general application of common human capabilities is definitely all that is required here. This is a skill that the very lowest people on the labor force can become good at.
Low tech use/application: The only real major piece of equipment needed to build a tire building is a backhoe. This is a common piece of equipment needed for all buildings of any type. Backhoes and operators rent almost anywhere for 30 – 50 $US per hour. Other typical toosl needed are a chain saw, skill saw, and a cement mixer. Common people use these tools all the time and theu are very easily accessible to all. This places the building of an earthship easily within reach of typical contractors and owner builders.