Beavers and wasps can build their own homes… — Michael Reynolds
Modern Earthships are shelters built to sustain their occupants by providing energy, water, and waste management through the use of passive systems. They have been designed to meet the rigorous criteria that are found in the building codes of so many western governments. While these modern Earthships are quite pleasing structures, they owe their heritage to a series of evolutions Michael Reynolds developed over a 40+ year period in remote lands surrounding Taos, New Mexico in the United States of America. While experimenting with recycled materials for construction, a design known as “the hut” was born of earth-rammed tires, aluminum cans, cement, and some metal framing. It is an ultra light house in every sense, except physically.
The core value of the hut is that it can be deployed anywhere in the world with the waste materials of the location becoming much of the construction material. This reduces both the cost and the energy input of the structure, often resulting in carbon negative buildings, and over time the hut will provide your basic needs carbon neutrally. The construction can be accomplished by anyone fit enough to hammer dirt; there are no special skills and only basic hand tools are required. It is a great training structure because of the shallow learning curve, as well as being modular in design. After you have finished your first hut, you can build more next to it to create a chain of “U” rooms that are attached by a main hallway similar to the more modern Earthship designs.
The main way the hut aims to reduce its impact during construction is through using ‘waste’ materials. The recycled items include tires, cardboard, glass, plastic and aluminum containers, as well as clothing or rags. Many of the other items, such as rebar or doors, can be salvaged to reduce the impact of the project further.
Modern building techniques utilize a great deal of wood that is not available in much of the developing world, and is quickly becoming scarcer in the developed world. The lack of resources often coincides with large garbage dumps that can be gold mines of materials to the savvy eye. Beyond the aforementioned, the metal sides of washers and dryers can be re-purposed as large shingles, or wattle-style wall panels.
A major component to the construction of Earthships are recycled tires. These can be hammered full of local dirt, sand, and debris to form 136kg (300lb) “bricks”. These preform similar to a thick earthen wall, but have the added bonus of being wrapped in an extremely durable tire. The tires are wide enough so that no foundation is required; the ground can be leveled and the first row of tires pounded into place with no major preparation to the ground. This also mates the hut with the Earth. This provides another degree of insurance against earthquakes.
By using aluminum cans, you can form custom walls and frames of all sorts. The cans create a lattice effect in the cement that is very strong while at the same time reducing the weight and required materials. Glass bottles can also be used to add a stained-glass effect to your wall. Cut 2 colored bottles in half and duct tape them together. When you lay this bottle/brick in place allow the edges to stick out a little bit so that they will be flush with your finished plaster wall. The bottles can also be used as filling space between the tires as you plaster your interior.
Glass bottle wall
Depending on the climate, a one or two layer roof can be installed. In hot climates the second roof acts as an umbrella, shading the inner roof. In colder climates the space between the roofs is insulated. More moderate climates, or hot climates with sufficient shade to keep the house out of the sun, may be able to function acceptably with only a single roof layer.
The roof frame is constructed of rebar and chicken wire mesh; it is attached to rebar that extends past the top of the tire wall. Once the frame is in place you will need to install your vent or solar chimney. Good circulation and venting of the air in an Earthship is important because the soil used can off-gas things like radon that you do not want lingering in your house. Earth tubes and a solar chimney can keep sufficient fresh air circulating. Flat timber roofs or thatch can be applied to the hut design with very minor modifications.
Cover the wire frame by dipping recycled clothing into a cement mixture and apply them to the frame as in paper-mache. This layer can then be built up with several scratch layers and eventually finished with a smooth layer. The roof will be surrounded by a gutter to direct rain water into the cistern.
By utilizing the cement can-wall technique you can create cisterns of varying capacity. The construction is straightforward and similar to the hut design. You can build at the surface of the ground, or, ideally, you can partially bury the cistern. A rebar cement roof, tin, thatch, or any local roofing material will suffice. The cistern can also be placed below the hut in a modified design; this placement has the added benefit of functioning similar to the Earth-tube cooling in that the cool water in the cistern will cool the hot air before it enters the living space.
Simple rain gutters can be made with a chicken wire frame coated with cement soaked clothing, and then adding a few more layers. These gutters, on both the hut and the cistern, will offer enough water for a couple to survive on, and grow a kitchen garden, given about 100mm (4in) of annual rainfall.
To allow for survival on such a small amount of rain requires multiplying the work your water does. The first use of your water will be drinking, bathing, or cooking. Next, the grey water from your sink and shower leads to a series of sealed garden beds, often indoors. This provides a nutrient rich drink to the plants while also cleaning up the water before eventually overflowing into tank that is used for flushing the toilet. Black water from a toilet then goes through an anaerobic septic system before being fed into another, outdoor, bed.
By adding a pressure tank and treatment filters, your rainwater will be indistinguishable, and likely purer, from standard utility water. In more advanced Earthships this water management system is called the Water Organization Module (WOM).
Most places of the world will require an adjustment to the interior temperature of the hut to make it livable. Both heating and cooling effects are passive and designed in. The fundamental basis of heating/cooling is that the Earth’s temperature is a fairly steady 14°C (58°F). By burying your house about a meter below the surface you will insulate the Earth’s wonderful thermal mass below you. The hut can then be heated with solar gain via the appropriate placement of glass given your latitude and situation. The Earth-filled tires, and the below ground wall, act as a great thermal mass to store energy all day, radiating it into the hut at night. The floor is another thermal mass that is heated similarly to what is taught in the Permaculture Designer’s Manual. The walls extend all the way to the ground, capturing the solar gain without allowing any to escape out the sides similarly to adding insulation around the skirt of your house.
Again following permaculture design directives, the hut should be positioned to catch the winter sun and shade out the summer sun. By orienting your roof-line to the sun angles you can allow in enough sun during the cold months of the year to charge all the thermal mass with heat. This heat radiates to warm the hut overnight, cued by the change in air and wall temperature difference. This often occurs around 3am, just when you might normally feel a little chilly.
To add passive cooling to the house you can utilize what are sometimes called “Geo-coupled thermal tubes”, simple pipes or passages below ground where hot air is cooled before entering the shelter. Dig a trench 1m deep and 20-50m long depending on your climate; the hotter the temperature, the longer the tube. By taking advantage of the thermosyphon effect created by the solar chimney exhausting the air in the shelter to create a lower pressure space, we allow a passive airflow to occur through the underground passage, into the shelter, and out the solar chimney. As the hot and humid air moves through the Earth-tube it will cool to the ~14°C (58°F) as well as draw the humidity out. Cool dry air entering the shelter will be the result.
When constructing your Earth-tubes, it is a good idea to grade them slightly away from the hut. As the humidity is deposited in the tube a buildup of water can occur. If the passage is graded away from the house, the water will pool away from the hut. This water soaks back into the ground, watering whatever you decide to plant around your Earth-tube’s inlet.
The hut design shines in the developing world where construction materials are in limited supply and unskilled labor is in surplus. Almost all places in the world where this kind of house would be welcomed also have an overabundance of tires.
Earthship creator Reynolds has proven the viability of the hut as a disaster relief structure in Indonesia, Haiti, and Mexico following their respective earthquakes and tsunamis. This relief structure is not a transitional one though; by conserving energy and building it right the first time, you can free up time in the future to further develop your region.
The hut is an extremely resilient structure and can stand up to tremendous forces while at the same time being “attached” to the Earth, not floating on a footer, to give it stability in an earthquake. The dome roof of the hut is a strong shape, but could likely be strengthened by building a buckminsterfullerene (or buckyball) frame to cement over. The shape of the dome also allows for the easy deflection of wind and water, making it ideal for standing up to tropical storms.
A concern often raised is the off-gassing of the tires. The study: "Use of Scrap Tires in Civil and Environmental Construction" May 10, 1995. Environmental Geo-technics Report No. 95-2, prepared by the Geo-technical Engineering Program Department of Civil & Environmental Engineering at the University of Wisconsin has determined that there are no adverse effects to building with tires in this manner. The cover page and more detailed information can be found here. http://earthship.org/offgassing
- Building a hut — Start to finish walk-through build
- Haiti — Overview of Earthship Haiti aid efforts
- Honduras, Belgium, Lakota Country, Mexico — Demonstration projects from around the world
- Garbage Warrior – A more detailed history of Earthships
Materials for one 12′ Hut
- 70 bags of cement
- 11 bags structolite
- 8 cubic yards concrete sand
- 6.5 cubic yards plaster sand
- 4 bags engineering fibers
- 2 bags calcium chloride
- 15 1/2” rebar, 20 foot length
- 5 3/8” rebar, 20 foot length
- 4 rolls bailing wire
- 2 rolls stucco netting
- 36 sheets metal lath
- 10 sheets greyboard
- 2 rolls 6mm plastic
- 1 stove pipe
- 1 storm collar
- 1 cap
- 1 window screen
- 1 damper/stove plug
- 2 rolls duct tape
- 6 tubes silicon caulk
- 1 tube liquid nails
- 2 sheets sand paper
- 1 bag chopped straw
- 6 gallon boiled linseed oil
- 6 gallon mineral spirits
- 5 gallon primer
- 5 gallon acryshield
- Lumber for door buck/frame
- Glass door
- Assorted nails
- Batting insulation
Total for the hut ~$2500USD.