[JandM]

Looking at house advertisements, 'rammed earth' was a new one on us, so we've just Googled it. What's it like in practice? What stops the whole place washing away when it rains?

[Wahlet]

Rammed earth is an ancient type of building. In fact, some say that about a third of the world's population still lives in some type of home built of unfired earth (cob, wattle and daub, rammed earth...). Modern rammed earth walls are made by compacting slightly moistened earth in steel or wooden forms with a pneumatic tamper. This creates a hardness not dissimilar to concrete. As long as the walls have sufficient protection from groundwater and driving rain, they can last thousands of years. There is an old saying, something like "Give it a good hat and boots, and it will last forever." There is nothing in the walls to rot or decay. Many of the old whitewashed thatched roof homes in England and Scotland have earthen walls, are well over a thousand years old, and are still occupied. In many climates earthen buildings have advantages over other types of building. The many tons of earth store heat in cold spells, and cool in hot spells. Occupants are almost always enthusiastic about its comfort. Rammed earth is growing in popularity in Australia possibly more than in any other country, partly due to the comfort it affords in a hot, dry climate. This type of construction is about as environmentally friendly as you can get. No toxic materials are necessary, at least for the walls, and when the house has reached the end of its useful life, the roof can be removed and the rain will bring the earth back to where it came from. I could go on and on. A dream of mine is to build a house of cob (straw, clay, and sand formed by hand - very sculptural).

Well, I could rattle on long enough to write a book. As you can tell, I have a slight bit of enthusiasm for earthen building. Hope this is of some help. The best way to learn for yourself would be to go visit such a house!