Question: Wouldn't the buildings erode easily?

Natasha Watson answered on 13 Mar 2013:

When building with any material it needs to be protected; steel rusts, and concrete can suffer from ‘freeze thaw errosion’ where water gets into small cracks in the concrete, then freezes and expands causing the crack to expand and the concrete to flake.

With natural materials such as straw and rammed earth its no different, but they are a more susceptible to water damage. They are protected by ‘giving them a good pair of boots and a good hat’. The ‘boots’ mean they are raised off the ground, either on a brick or stone ‘plinth’ so that puddles can’t form around them, and rising damp doesn’t get to them either. the ‘hat’ means that they are protected from rain dripping down their surface by a roof with an overhang.

This image imagines that you’ve cut the wall in half and are looking at its insides. It shows that the gravel bags are keeping the straw off the ground (boots) , and you can see that the roof juts out over the wall (hat)

The surface of the materials can also be protected with what’s known as a ‘rain-screen’ which is where a layer of material covered the structural material to protect it from rain.

In the image, the wall has been cut in half and you’re looking down into its insides. The ‘outer cladding panel’ is the raindscreen protecting the rammed earth.

Hope this answers your question!

Tish