Keeping the Costs Down / by Watershed Materials

One of the challenges facing the popularization of rammed earth is it’s installed cost.  It’s ironic that what might be viewed as a free raw material has evolved into an expensive finished product. In the past, probably the greatest appeal to building with rammed earth was its low cost. 

Soil was harvested on site, the forms were simple, and the work was done by hand.  Buildings served basic needs, with walls that were rough and only more or less plumb.  This practice remained the norm for a very long time, from early civilization through the middle of the twentieth century.  It still is the norm in rural China, the Middle East, and Africa.

When rammed earth began to re-emerge in the mid 1970’s, it was still considered an inexpensive wall system.  Soil was predominantly sourced on site, formwork was relatively simple, the architecture was linear, and unskilled labor could be used for most of the work.  Walls were a little ragged and unrefined.  Plaster was a common finish treatment.

Over the past few decades, rammed earth has grown in popularity, with an increasing number of professional builders developing the requisite skills.  Contrary to the law of supply and demand, however, in which competition reduces prices, rammed earth has become more expensive. 

Why is this?  The answer is complex, or rather complexity.  Rammed earth began as a simple system that recognized, even celebrated, the inherent flaws and unpredictability of raw earth. Over time, as builders improved their skills and the marketplace grew to appreciate the unique beauty of rammed earth, architects began to push the material to applications and expectations that were extremely difficult to fulfill. They were difficult but not impossible, only time consuming and expensive.  Gone were the days of simple forms, unskilled labor, and site-sourced materials.  In their place were elaborate formwork built and set by highly skilled carpenters, and imported screened soil and processed aggregates stabilized with 10% cement. Each course of soil in the forms must be carefully placed and conscientiously compacted, with the whole installation under the watchful eye of a paid special inspector.  Add color blending, strata lines, curves, rakes, niches, lintels, chamfered bond beams and watch the square foot cost approach Carrara marble. 

What can we do?  There are two solutions, and the good news is that they can co-exist.  On one hand we can continue to refine our skills and produce rammed earth with the look, feel, and price tag of art.  On the other hand, we can provide clients and architects with value engineering feedback on how to design efficiently for the material.

Rammed Earth is massive so keep it simple.  Rammed Earth is regional so source materials locally.  Appreciating the unpredictable character of finished wall surface celebrates the authenticity of natural materials and showcases its hand built qualities.

Rammed earth doesn’t have to be expensive.  Designed with the system in mind, it can be one of the best values in the building industry today.