Q: What are earthblocks?

A: Just dirt! Or rather, dirt which has some clay in it (12% - 25% clay is ideal – soil with higher clay content can be mixed with sand or sandier soil to get a “qualified” soil). The soil is usually obtained right from the ground at the building site. 65% of the dirt on the planet can be used to make earthblocks – and it can be found in virtually every location.

Q: How are earthblocks made?

A: Though all of these processes can be mechanized (requiring more fossil fuel and, therefore, more cost) the basic procedure is:

· The dirt (the “qualified” soil with some clay content) is broken up and larger gravel and stones are removed by shoveling it through half inch chicken wire screen.

· This dry soil is then mixed well (adding 3% - 7% lime or cement to the mix if you are making stabilized blocks). The mixing can be done by hand with shovels and rakes, adding just a little moisture to the mix at the end to get a 7% - 12% moisture content.

· The soil is compressed and shaped into uniform blocks in a hand- operated press.

Q: What is the difference between stabilized and unstabilized earthblocks?

A: An earthblock is stabilized by adding a small amount of lime or cement to the soil with some clay content. The lime with the small amount of moisture chemically combines with the clay, essentially turning back into limestone, locking in the sand and gravel to form a brick which is waterproof. Stabilized earthblocks are more expensive because of the cost of the stabilizer and have to “cure” for a month before they can be used. Unstabilized earthblocks are waterproofed by coating the outside of the structure with a lime or cement plaster made from a wetter – plaster-like consistency - mixture of the clayey -like soil mixed with lime or cement.

Q: Why would you want to build with earthblocks rather than concrete?

Q: Are there other advantages to earthblock houses?

A: An earthblock building is not only healthy for the individual, but also for the planet. Dirt, an earthblock's primary ingredient, is a renewable, non-toxic natural resource. Earthblock walls are virtually breathable, soundproof, bug-proof, fireproof, and even bulletproof! Requiring less transportation of materials than conventional construction methods, earthblocks have a lower embodied energy than conventional building materials. It takes 100 times more energy to make concrete than it does to make comparable amounts of earthblocks, because concrete is made under extremely high heat and the pollution from manufacture of concrete is a major contributor to global warming. Using wood for buildings contributes to deforestation, which is a significant problem in much of the developing world. In addition to being good for the environment, energy savings are immediate because the thermal mass properties of earthblocks results in lower heating and cooling requirements.

Q: How long does it take to build an earthblock home?

A: It depends on the actual size, but a small home requires 5,000 blocks and the hand-operated press we want to buy can be used to produce 125 earthblocks per hour or about 1,000 blocks per day, with a work crew of seven people. Therefore, it would be possible to produce the earthblocks for a house in a week. The actual construction would take longer, but within a similar timeframe to build a small concrete block or wood home.

Q: Are these structures strong?

A: Yes, both stabilized and unstabilized earthblocks are appropriate for earthblock buildings and meet U.S. building code standards for compression and modules of rupture tests. The durability of an earthblock building will allow it to last for centuries! Ancient earthen structures still stand today in certain parts of the world. The expected life span of a wood frame building is just 70 years. Earthblocks have proven to be waterproof, fireproof, bug proof and bulletproof, and with bamboo or rebar reinforcement, these structures can be built to resist earthquake damage in seismic zones.

Q: You’ve mentioned the structure, but you haven’t talked about the roof. Are the roofs also made of earthblock?

A: While earthen roofs of various kinds are possible, we hope to use “thin-shelled concrete roofs.” These have proved to be much cheaper and more durable and less noisy than the typical  corrugated metal roof used in many impoverished communities throughout the world.  Thin-shelled concrete roofs are made with concrete, sand and latex mixtures layered over a simple mesh covered frame.

Q: How do you know the structures and the roofs will be properly built?

A: We have enlisted the assistance of experience professionals. For the training and to coordinate the construction supervision on these initial projects, we are planning to hire Tierra y Cal, a team of builders of earthblock structures comprised of U.S. and Mexican citizens with twenty years experience in earthblock construction. In addition, we have enlisted the assistance of Birambye International, a Colorado-based sustainable development public charity which has primarily worked in Rwanda. The professionals, including engineers, in Birambye have been trained by George Nez, the developer of the thin-shelled roof. He has built these inexpensive and very durable roofs in poor communities throughout the world. Our friends in Birambye are excited about assisting in this project. We plan to have professional expertise available for guidance at every stage of this project. Making earthblocks is not hard to learn. It is has been taught in communities throughout the world. We hope this knowledge will allow the people we work with to cheaply, effiiciently and- once trained- autonomously pursue the building needs of their own communities.

A: Check out the websites at:  www.tierraycal.com, www.earthblockinc.com,  and www.earth-auroville.com