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The Eartha Madre Project

Adobe—an ancient and renewable building material

Adobe mud blocks are one of the oldest and most widely used building materials. Adobe is a low-cost, readily available construction material, usually manufactured by local communities.  Use of these sun-dried blocks dates back to 8000 B.C.  Around 30% of the world’s population live in earth-made construction. Approximately  50% of the population in developing countries, including the majority of the rural population and at least 20% of the urban and suburban population, live in earthen dwellings worldwide.

Interior Adobe Wall Construction

Adobe walls in the east bedroom wing provide thermal mass for the solar hallway

We constructed the adobe walls ourselves because the construction process is relatively simple and did not require additional energy resources.  During our construction process we were constantly supported by synchronicity and yet another example was that the individual who was our licensed electrician, we later found out had also worked extensively with adobe building in Tucson in the 70s.  It was a medium that he enjoyed working with and he was enthusiastic to be our lead man for the adobe wall construction.  Adobe construction, in combination with good passive solar design, makes for an effective energy-saving solution in cold winter areas like ours. The use of high-mass walls, good stem wall and ceiling insulation and a large south solar aperture, can cut energy use in January by 60% or more. We absolutely found this to be true when our radiant floor heating system was affected by a late fall lightening strike that shut down our hydronics from mid November thru early February.  With only our European masonry heater for heat, the inside temperatures didn’t fall below 65 degrees even when the outside temperatures were in the single digits.  The high-mass earth walls also eliminated cooling costs in our hot summer Arizona location.  We have found the old adobe saying "cooler in summer and warmer in winter” is absolutely true.  We have no cooling system in this 4600 foot house and even when outside summer temperatures range in the high 90’s, no additional cooling is required and the inside temperature remains at a fairly constant 73 degrees even on the hottest days.

Unique shaped hallways and arches lend themselves readily to adobe construction

Natural mud mortar from dirt surrounding the construction site is what we used between the courses of blocks.  Adobe manufacturing is an ancient technique that involved mixing dirt and water.  Other ingredients such as straw, manure and agave are often added for strength and durability.  This mix was then poured into molds to dry in the sun for up to 30 days.  We purchased all of our adobe from the Pascua Yaqui tribe in Tucson, AZ.  The Yaqui people have been using adobe construction for hundreds of years. Today the Pascua Yaqui Adobe company manufactures blocks using state of the art equipment.  Their adobe is made using a computer regulated hydraulic press machine that takes the moist soil and compresses it with over 4000 PSI of pressure to form a solid block.  They manufacture both stabilized and unstabilized adobe.  Stabilization means that the blocks are water resistant and can be plastered or left exposed and sealed.  The two additives normally used for stabilization are asphalt emulsion or Portland cement.  In keeping with our “healthy home” intention and because the blocks were for interior applications only, we selected unstabilized adobe due to its 100% natural composition.

Finished adobe walls

These 100% natural unstabilized blocks are easy to work with and can be left either natural or finished.  The finish we chose to use on the adobe walls was extremely easy and involved a bucket of water and a large, heavy bristle brush.  The brush was dipped in the water and then “painted’ or scrubbed across the adobe.  This method of brushing the natural adobe blocks with water created a light slurry from the adobe dirt mixed with the water and the resulting finish was smooth and uniform in its appearance.