Rammed earth is a timeless construction method that offers a modern solution to fire resistance. The ancient technique utilizes raw natural materials such as earth, chalk, sand, gravel, etc. which are compacted to form the building’s structure including the foundation, floors, and walls.

Photo courtesy of Rammed Earth Construction

Photo credit: Waugh Thistleton, courtesy of Treehugger.com

The most famous example of rammed earth construction is the Great Wall of China, built over 2,000 years ago. While some of the materials may have changed since then, the general methodology has remained the same. To create the structure the materials are dampened and “rammed” into a formwork, and once the mixture is dry and compressed, the formwork is removed to reveal “a beautifully stratified surface” (thearchitectstake).

*Photo Credit: Jessie Gillan, courtesy of Rammed Earth Works*

The benefits of rammed earth include low maintenance, energy efficiency, durability and, most significantly, fire resistance. “Earth doesn’t burn” explains Rammed Earth Constructions. A study conducted by the Department of Housing and Construction in Queensland, Australia, concluded that “rammed earth is very fire resistant and that it is one of the most heat-resistant building materials (stabilizedearth). As rammed earth walls are load-bearing, these structures are unlikely to need other framing materials, such as wood, further reducing the fire (and pest) risk. The combination of non-flammable materials thickly and tightly packed reduce the risk of combustion.

A low carbon footprint makes rammed earth buildings eco-friendly. According to the World Economic Forum, global cement manufacturing is responsible for 8% of the global CO2 emissions. Conversely, the rammed earth method typically relies on local, natural and sustainable resources so there are fewer emissions in the creation and transportation of materials. It is also energy efficient as the high thermal mass will absorb and store heat from the sun during the day and then release the stored heat when the temperature gets cooler in the night. Thus, homeowners can save on heating and cooling systems and reduced energy bills. Rammed earth structures are also typically very durable and low maintenance. While rammed earth walls can be painted, left exposed, the natural patterns and stripes make unique and striking designs.

Photo courtesy of Amazing Architecture

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For all the benefits of rammed earth there are several drawbacks ranging from cost to insulation. The unique process of rammed earth requires highly skilled professionals and laborers who are experienced in this technique (read “costly”). It is also a labor-intensive and time-consuming process compared to concrete. And in cooler climates, insulation will be necessary (buildingrenewable).

Amazing Architecture explains that climate concerns must be considered when using rammed earth. “The materials used for the soil must be carefully considered to match the temperature and humidity of the location or the walls could degrade rapidly.” Therefore, in some cases, more effective soil must be transported in. Moisture, from humidity or ground water, can also affect the durability of rammed earth walls. To combat this, foundations should be raised above the ground, have proper drainage systems, a sealant applied, and a small amount of concrete could be added to the mixture. All these factors reduce the environmental benefits slightly and increase costs. (An added benefit of adding minimal concrete to the mixture is that it can increase the load bearing capacity, explains Archdaily.)

Regardless of the pros and cons of rammed earth, the beauty of this ancient technique in undeniable. Rammed earth is one of the longest-enduring materials; it was employed by the Babylonians for basic temples and fortresses. Today, it has been elevated into a unique and beautiful material. David Easton, President of Rammed Earth Works, who wrote the definitive book on this technique (The Rammed Earth House), has “transformed it from a rudimentary construction process into something closer to an art form.” His structures evoke a sense refinement, beauty, and a feeling of harmony with their surroundings.

Photo Credit Matthew Millmam

Photo Credit: Adrián Gregorutti