Rammed earth is an ancient construction technique that consists, very simply, of using molds to compress earth inside them. These molds, or formworks, are tied together so that the pressure of the compacted earth does not force them to move. The result is solid walls of raw earth, of great thickness (between 30cm and 50cm) and with excellent environmental qualities. In addition to being a totally natural technique, its result is so subtle that it does not require any finishing, besides having a great thermal inertia and a very good hygrometry. To ram the earth, a manual hammer, wood or metal, or a pneumatic rammer can be used, which reduces effort and provides more homogeneous results. However, many prefer to use the manual rammer, because of the connection it establishes between the earth and the person who is treating it.
As unstable as it may seem, a good rammed earth wall can last forever without failing or suffering irreparable injuries: a good example of this is the Alhambra in Granada and its forts, which date back to the XIIIth century. In Spain and France, as well as in Latin America, it is very common to find historical buildings built with this technique.
We're currently creating a manual to distribute the plans of the formworks and the different tools needed to put this wonderful technique into action. We will publish it as soon as we have it!