Chelsea Green Publishing: First things first: what exactly is adobe?
Lisa Schroder: Adobe is an earthen construction method in which sun-dried bricks are made from a mixture of sand, clay, and sometimes a strengthening agent, such as straw, lime, cement, bitumen, or others.
CG: Most Americans, if they think about adobe at all, think of it as a purely regional building material, limited to New Mexico and nearby southwest locales. But you began building with adobe bricks in New Zealand, of all places. How did that happen?
LS: During my engineering studies at North Carolina State University I began an interest in green building. At the time (1998) there wasn’t much activity in the field, other than promoting more natural paints or carpets. When I moved to New Zealand to study architectural design, I discovered there was a renaissance occurring with earth building. I began working as a designer for adobe homes in 2000 and fell in love with the material and the process. It was fascinating to make bricks and build walls with local material from the nearby quarry. I knew I had found my niche in construction once I was introduced to adobe building.
CG: How adaptable is adobe to wetter or colder climates?
LS: Adobe is best adapted to wetter climates with the addition of a stabilizer. We find Portland cement to be the most user-friendly material to use, as it fortifies the bricks to be stronger and more resistant to moisture. We can make bricks in the rain and build our walls with more confidence in wetter climates.
In colder climates, it is always best to use solar passive design, which allows you to use the sun to warm the inside of the building as best as possible. In more extreme climates, the thickness of the walls can be increased so that it takes longer for the heat to be released outside. The solid thickness of the walls have a high thermal mass, which improves the thermal dynamics of the home.
CG: Does building with adobe impose architectural limitations?
LS: There are certain limitations to adobe in terms of how high you can build. Building standards require that the taller your structures, the wider the walls have to be. But with a typical 12” thick wall, you can build up to 2 stories. There are, however, beautiful architectural elements of adobe that can be incorporated into any design, such as adobe brick arches, built-in niches in the wall, timber lintels, and a variety of finishes to the wall to suit your individual style.
CG: In your book, you emphasize earthquake resistant construction. Why is that so much of a concern for you?
LS: Unfortunately many lives have been lost during earthquakes from adobe brick homes that collapsed because they were not properly built This has given adobe an often unfair reputation since they can be built to withstand high earthquake zone regions. Rather than replace adobe construction methods with less sustainable construction materials that have a greater impact on our environment, we should educate ourselves how to improve upon this method of building, especially in areas where adobe is the predominant building material.
CG: How can an adobe brick structure be built to withstand earthquakes?
LS: Engineering elements, such as bond-beams, vertical and horizontal reinforcing, and proper foundations, need to be incorporated into the adobe home in an effort to protect the lives of almost half the world’s population that live in them.
CG: What are the advantages to building with adobe bricks?
LS: Adobe has one of the lowest levels of embodied energy of any material used in construction today. Bricks can be made by hand and on-site using unskilled labor, local materials, and easily obtainable tools. Due to the forgiving nature of the slightly irregular bricks, novices can become proficient adobe bricklayers in just a day. Sturdy, solid, and energy efficient walls can be achieved by all builders to create a home that will last for generations with little to no structural maintenance.
CG: How easily can homeowners-to-be build an adobe home by themselves?
LS: There’s often nothing easy about a labor of love. Any construction process will go through times of difficulty and hardship. The difference with building your own home out of earth is the feeling of satisfaction and pride in your walls. By choosing to build with adobe, we are making a choice that eases the impact on our environment for years to come. The bricks may be heavy to work with and more expensive than timber frame to construct, but you can rest assured the final product will be in a class of its own.