Rammed earth from the French word pis’e de terre is just that, earth that is rammed or compacted into a solid building material. This style of building has been used for thousands of years, and is also currently used today. Many structures throughout time were build using earth and naturally available resources. There are several ways to build structures with rammed earth, and it can be incorporated with other natural building techniques. The earth use to build these structures has very little strength while in a pile. Although, when compressed it can become very strong. The picture below demonstrates how the walls are built in layers, and then compacted.
The History Of Rammed Earth
Rammed Earths history is intertwined with human civilization as a whole. Before humans had the ability to produce non-natural materials (plastic, treated wood, concrete), we had to use naturally occurring materials. Rammed earth was used as far back as 5000 BCE, by cultures living along the Yellow River in China. Rammed earth was also used to construct parts of the Great Wall of China, starting in 220BCE by the Qin dynasty.
In the early 1800’s rammed earth began to become popular in the United States, and many structures were build in this fashion. Popularized by the book Rural Economy by S.W. Johnson, written in 1806.
One of the first large pis’e de terre build in the United States was the Church of the Holy Cross, built in 1850-1852AD. It is still standing today in Sumter, South Carolina. In 1926 The United States Department of Agriculture released a guide on how to build rammed earth houses called “Farmers Bulletin No. 1500″. It gives a detailed description on how to build a rammed earth structure or dwelling. It also inspired a boom of rammed earth houses to be constructed. Many areas in the world still use earth as their primary building material.
Advantages of Using Rammed Earth
Rammed earths homes have many advantages; one of them is cost. Just imagine that the majority of your building materials are already “on site”. Because of this there is very little need for costly supply’s that have to be imported from other states/ countries. Many of us don’t think about the long distances that our building materials have to travel to get to our construction sites. The transportation of these materials is also added into the cost, and there is an ecological detriment from the fuel used to move them.
Heating and Cooling
Because of the thick dense walls rammed earth structures have, they are great at regulating temperature. The earthen walls have a great thermal mass quality; this gives the structure the ability to hold heat in the winter and keep cool in the summer. How this works is very simple. During the day when the sun hits the earthen wall, the energy (heat) is store in the walls. At night when the temperatures drops, the heat is slowly released into the structure. The reverse happens in the hot season; at night the temperature drops and keeps the house cool during the day. Because of the thick walls, many of these rammed earth structures have a great “R-value” (up to R33 or higher). Furthermore, because of the high R-value little to no insulation is needed, saving additional money on building costs.
As mention above many rammed earth buildings have stood the test of time. When building with a material that can be steadily eroded, you want to make sure you have a sound foundation and a good over hang on the roof; or as the saying goes in Europe “make sure you have a good hat and boots”.To increase durability of the walls they can be sealed with a natural oil or other hydrophobic (water fearing) sealants. Furthermore, in areas prone to earthquakes re-bar reinforcement may be considered to help with cracking and or collapsing. Although concrete is more durable, its production comes at a cost to the environment; it also add additional cost to the project.
What can be more ecological then building a house out of the earth? When using locally available materials you are directly affecting numerous ecological issues at the same time. You are also reducing mass amounts of waste and toxins such as paint, cement, tar, plastic, ect. Over seven percent of global CO2 emissions come from the production of cement, and concrete represents nearly one half of the 136 million tons of construction waste generated each year in the United States. (United States Green Building Council 2005). By building the walls with a natural material, it will give them the ability to breath. This will help with the air quality, and prevent cracking in your residence.
Although having your own rammed earth house may be amazing, there are possible challenges along the way. The main one being that rammed earth construction is very labor-intensive. Regardless if you are hosting a work for experience volunteer program, or you do it yourself; there will be allot of hard work involved. Furthermore, if you need to hire help, that can significantly increase the cost of building your structure. Another challenge is dealing with the code or ordinances; whether it be city, state or federal. Also getting a loan from a financial institute may be difficult, depended on the code in your area. Although there will be struggles along the way; many things worth having are challenging to achieve.
“Difficulties strengthen the mind, as labor does the body.”